3117 swimming pools and electric space heating the case for coverage by the bca

8/13/2019 3117 Swimming Pools and Electric Space Heating the Case for Coverage by the BCA

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FINAL

Swimming pools and

electric space heating

The case for coverage by the Building Code of

Australia

January 2009

Prepared for the Australian Building Codes Board

by

George Wilkenfeld and Associates

GEORGE WILKENFELD AND ASSOCIATES Pty Ltd

ENERGY POLICY AND PLANNING CONSULTANTSPO Box 934 Newtown NSW 2042 Sydney Australia

Tel (+61 2) 9565 2041

Swimming Pools Electric Space Heating 1


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Contents

Summary ........................................................................................................................... 3

Swimming pools ....................................................................................................... 3

Public Pools .............................................................................................................. 4

Electric Resistance Space Heating ........................................................................... 71. Background................................................................................................................... 9

1.1 The BCA and Energy- and Water-efficiency ........................................................ 9

1.2 This Paper ............................................................................................................... 9

Swimming pools ..................................................................................................... 10

Electric Resistance Space Heating ......................................................................... 10

1.3 Swimming Pools ................................................................................................... 10

2. Domestic Swimming Pools ........................................................................................ 12

2.1 Number, and type of pools .................................................................................. 12

2.2 Energy and Water Impacts .................................................................................. 15

2.3 Elements of energy use ........................................................................................ 16

Pumping .................................................................................................................. 16

Sanitisation, timers and controllers ........................................................................ 17

Heating ................................................................................................................... 17

2.4 Standards and levels of efficiency....................................................................... 18

2.5 Potential Role for BCA ....................................................................................... 19

3. Shared and Public Pools ............................................................................................. 21

3.1 Type and number of pools ................................................................................... 21

3.2 Energy and Water Impacts .................................................................................. 22

3.3 Elements of energy use ........................................................................................ 24

Pool water management and conditioning ............................................................. 24

Heating and Ventilation of Pool Buildings ............................................................ 25User amenities ........................................................................................................ 25


4. Fixed Electric Resistance Space Heating ................................................................... 27

4.1 Types of Fixed Electric Resistance Heating......................................................... 27

Underfloor (slab) heating..................................................................................... 29

Heat banks .............................................................................................................. 30


References .................................................................................................................. 34

Appendix 1: California Title 24 Requirements: Swimming Pools............................. 35



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Summary

The Building Code of Australia (BCA) is becoming increasingly involved in areas of

design that impact on the on-going energy use of buildings. The main rationale is to

address market failures. Many of the parties who plan and construct new buildings have

a reduced incentive to incorporate design features and services which could cost-

effectively reduce lifetime operating costs, because it will be the ultimate buyer,

occupant or tenant who will meet those costs.

The impending implementation of the Australian Governments Carbon Pollution

Reduction Scheme (CPRS) is expected to lead to higher energy prices. This will

strengthen the case for the BCA to incorporate provisions which increase the energy-

efficiency of buildings, because the financial costs of the failure of the market to

provide the most cost-effective level of building efficiency will be higher. The BCA

could raise the stringency of standards, or add provisions for building types and services

not yet covered.

This study was commissioned by the Australian Building Codes Board (ABCB) Office

to review the case for BCA coverage of:

swimming pool and spa pool energy use (and the emissions related to that energyuse); and

fixed electric resistance space heating.Swimming pools

Swimming pools are energy- and water-intensive structures. In 2007 about 945,000Australian households (11.7% of the total) had a swimming pool, and swimming pools

and spa pools accounted for about 3.3% of total household electricity use: more than

clothes dryers and dishwashers combined. In the homes which had a pool, it was almost

always the largest single electricity user, averaging 1,930 kWh per year, compared with

720 kWh per year for refrigeration. The great majority of pool electricity use was for

filtration pumping.

Pools and spas in hotels typically account for 4% to 8% of the total building energy use,

and in apartment buildings they typically account for 10% to 20% of common area

energy use. Aquatic centres are among the most energy-intensive of building types,

with energy per floor area typically 5 times that of office buildings.

These statistics indicate that including the energy use or energy-efficiency of swimming

pools in the BCA deserves consideration.

Constructed swimming pools or spa pools are usually subject to local government

planning approval, which represents a point at which BCA compliance could be

enforced. However, council requirements vary for stand-alone spa pools brought to site

as complete assemblies they may be listed as a complying development, exempt

development or not specifically mentioned at all. Therefore the full effectiveness of

any BCA provisions related to stand-alone spa pools is subject to uncertainty.



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There are no accepted measures or standards of overall energy performance for

domestic swimming pools, and performance can vary significantly with the owners

settings and preferences. Therefore there is no basis to adopt energy design standards

for entire swimming pool systems, or to test whether those standards are achieved in

designs or even in post-construction operation.

It is however possible to set performance standards for selected pool components, and

to require design features which are known to lower energy use in operation. The NSW

BASIX scheme requires a BASIX certificate for swimming pools and/or spas with a

combined volume of 40,000 litres or more. The applicant must enter data on volume,

location (indoors/outdoors), method of water heating if any, and whether outdoor pools

are shaded or equipped with a pool cover. Electric resistance heating is not permitted for

swimming pools.

The CaliforniaEnergy Efficiency Standards for Residential and Nonresidential

Buildings go considerably further than BASIX, in that they impact on the actual

hydraulic design of the pool, pump efficiency, pump control strategy and heaterefficiency.

An Australian Standard for testing and energy efficiency rating and labelling of

swimming pool pumps is near completion. The Standard will also contain a minimum

energy performance standard (MEPS) level which will be relatively low, at least

initially. Subject to passing a regulatory impact assessment, it is envisaged that the

Standard will be made mandatory under State legislation, in the same way as other

appliance labelling and MEPS standards. The Commonwealth-State Equipment Energy

Efficiency Program has also undertaken to sponsor the development of a method of test

and a rating system for gas pool heaters.

There is a case for including the following provisions in the BCA at the earliest

opportunity (subject to formal cost-benefit analysis):

1. Requirements for pipe sizes and layout which reduce resistance to water flow,and so reduce the energy requirement for filtration pumping (eg 50 mm

minimum pipe diameters and gradual bends rather than 90elbows);

2. Prohibition of the use of electric resistance water heating for swimming pools.(As very few electric resistance heaters are used on swimming pool heating, this

is large a preventative measure). This leaves the alternatives of unboosted solar,gas and heat pump water heating;

3. Prohibition of the use of electric resistance water heating for stand-alone spapools (other than single-phase electric resistance heaters built into the

recirculation systems of fully assembled stand-alone spa pools, or electric

boosting of solar water heaters). This leaves the alternatives of solar, gas and

heat pump water heating;

4. A requirement that all heated spa pools meet a specified level of thermalinsulation, and be fitted with removable covers that also meet a specified level

of thermal insulation. This should apply to both stand-alone and constructed spa



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pools, if these can be covered by the BCA (if not, appliance energy efficiency

standards should be developed for stand-alone spas);

5. A requirement that all swimming pools equipped with heating (of any type) befitted with a removable pool cover, whether the pool is indoors or outdoors;

6. A requirement that all swimming pools and spa pools be installed with one ormore user-adjustable timers or other control devices which limit or manage the

hours of pump operation. (As very few pumps are installed without timers, this

formalises prevailing practice).

There may be a case in future for including the following provisions in the BCA:

7. Minimum energy efficiency levels for pump-units, that may be higher than thegeneral MEPS levels adopted for those products. This should be considered

once mandatory energy labelling and MEPS is implemented for pump-units, and

sufficient information is collected on the sales-weighted energy-efficiency ofpump-units installed in new pools;

8. Minimum energy efficiency levels for gas pool heaters, that may be higher thanthe general MEPS levels adopted for those products. This should be considered

once mandatory energy labelling and MEPS is implemented for gas pool

heaters, and sufficient information is collected on the energy-efficiency of pool

heaters units installed in new pools;

9. Requirements for pump-unit configurations and control strategies to limit powerand rates of flow and to prevent the installation of over-sized filtration pumps

which would operate at low efficiency much of the time (as in California).

These issues should be reviewed from time to time as information accumulates.

Public Pools

Public pools, which are open to all users, range from single unheated outdoor

swimming pools run by a municipality to multiple Olympic standard pools enclosed

within large buildings, or aquatic centres.

Shared pools are typically controlled by a buildings owner or body corporate, and arefor the use of any authorised person: eg swimming pools in the common areas of

apartment buildings or hotels, where the condition of use may be tenancy of an

apartment or being a guest at the hotel.

Although there are no comprehensive data, it is estimated that there could be 1,000 to

1,500 public pool complexes in Australia, many with more than one swimming pool. It

is also estimated that there could be 8,000 to 10,000 shared swimming associated with

apartment buildings, hotels, clubs and fitness centres.

Shared and public pools use energy for the same main purposes as domestic pools:

water filtration, sanitisation and heating. However, the amount of energy used per pool



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is much higher because average water volume is higher, bather loads are high and the

sanitisation standards for public pools have to meet public health regulations.

In effect public and shared pools need to be sanitised and filtered continuously while

open to the public, as distinct from domestic pools, where filters and sanitisers only

need to operate 15% to 25% of the time, even in the swimming season.

The information about water and energy use in public pools in Australia is rather

limited, although several studies currently under way should improve this situation

during 2009. Information about shared pools in hotels and apartment buildings is even

more limited.

In general, the same energy and water uses are present in public pools and the buildings

which house them as for domestic pools, but on a much larger scale and designed for

high intensity of use.

There are however several important differences in design approach:

Public pool design tends to involve engineers, architects and other buildingprofessionals, whereas domestic pools tend to be designed by builder-packagers;

Many clients commissioning public pools are well aware of the high operating costs,and will instruct designers accordingly, whereas very few domestic pool clients are

aware of this;

Public pools must meet a range of stringent and regularly enforced health standards,some of which are quite prescriptive in terms of sanitisation and water turnover,whereas the standards for domestic pools are in effect advisory and not enforceable;

Many public pools are housed in buildings, or parts of buildings, which have highservice requirements and energy use of their own and interact with the general

building services in complex ways (some of which offer opportunities, eg use of

waste heat). Very few domestic pools are in this situation.



10. Definition of a distinct class of non-domestic swimming pools and spa poolsthat correspond to the definition of public pools used in health regulations;

10. Prohibition of the use of electric resistance water heaters for public swimming

pools or spa pools. The alternatives would include solar (unboosted, electric-

boosted or gas-boosted), gas, heat pump or waste heat;

11. A requirement that all public spa pools be fitted with insulating covers and have

a minimum level of thermal insulation;

12. A requirement that all public swimming pools equipped with heating (of any

type) be fitted with a removable pool cover, whether the pool is indoors oroutdoors;



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As nearly all public pools would have special design requirements which are likely to

involve engineers or other specialists, general design provisions relating to pipe sizes or

controls, which are appropriate for domestic pools, are not appropriate for public pools.

There are at present no general Australian energy or water performance standards forpublic pools, for buildings housing public pools (eg Class 9) or the parts of buildings

housing public pools (eg parts of Class 2 or 3). There are several projects under way to

gather data on which such performance standards could be based.

Even if performance standards were developed, it would also be necessary to develop

methods of predicting performance so that compliance with those standards could be

established. It may then also be possible to establish deemed to satisfy provisions: eg

the recovery of heat from moist air ventilated from the pool hall.

There may be a case for including such provisions in the BCA in future, and these

issues should be reviewed from time to time as information accumulates.

Electric Resistance Space Heating

Electric resistance heating is currently the most greenhouse gas-intensive means of

space and water heating, even though it is close to 100% efficient at the point of

conversion. This is because the great majority of electricity generated in Australia is

from the combustion of coal, leading to high emissions and low conversion efficiency at

the power stations. Despite the CPRS, the average emissions intensity of electricity

supplied in Australia is still projected to be about 75% of todays levels by 2030.

Electric resistance heaters have the advantage of flexibility of location, since no pipes or

flues are necessary. The relatively low capital costs can make electric resistance space

heating attractive to home builders where some form of fixed heating is required. The

main disadvantages are high running costs and high greenhouse gas-intensity.

Electric heaters up to 2.4 kW output can be plugged into a power-point, whether or not

the heater is fixed to the structure or portable. Larger capacity units need fixed wiring,

so need to be installed by a qualified person. The effectiveness of BCA coverage of

plug-in fixed electric heaters is likely to be limited, because any provisions can be easily

circumvented by simply fixing the heaters after completion and plugging them in.

The only types of electric resistance heater that could be effectively covered are:

Heaters which are part of the building fabric, eg physically integrated into the floor,wall or ceiling, rather than fixed to their surface; and/or

Hard-wired heaters, which may not be connected to the electricity supply by astandard power point, because they draw more than 10 amps, and/or require a 3-

phase supply, or for safety reasons.

These definitions would cover electric slab and underfloor heating, and heat banks, both

of which are relatively rare in existing buildings, and probably even more so in newones. It has been suggested that if electric storage water heaters are excluded from new



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dwellings on the grounds of greenhouse gas-intensity, then so should electric storage

space heaters. This does not necessarily follow.

Water heaters deliver a highly standardised service so qualitative differences between

types and energy forms are small. As users have no strong preferences (other than not

running out of hot water), they are usually content to leave the decision to the builder orother intermediary: this accounts for the split incentive market failures which the BCAs

requirements for water heaters are intended to address.

Space heaters, on the other hand, deliver outputs that are qualitatively different. People

have strong preferences for convection, conduction or radiant forms of heating, for real

flames (or flame effects), and even for different fuels. It is especially likely that

preferences will come into play when selecting electric heaters that are moreexpensive

to buy and install (as is the case with slab heating and heat banks) and less costly to run.

This is the opposite of the water heating case, where lack of user involvement tends to

lead to the outcome with the lowest capital cost but higherrunning cost.

The diverse and specialised nature of space heating also means that there are no direct

non-electric alternatives for many electric resistance heaters, unlike electric water

heaters, where the obvious alternatives are solar-boosted electric and heat pumps even

before considering other fuels.

While there does not appear to be a case for the BCA to set performance requirements

that would prohibit the installation of fixed and hard wired electric resistance heating,

there may be a case for requiring design elements and features which would reduce the

risk of energy waste from such systems. The BCA already requires mandatory under-

slab and slab-edge insulation where in-slab heating is to be installed.

Other provisions could include:

14. For in-slab and under-floor electric resistance heating:

a. mandatory zoning, so that heating to each space can be switchedseparately

b. all zones to be controllable by timers or programmable controllers andthermostats

c. maximum power loads, eg 110W/m2for living areas and 150 W/m2forbathrooms.

15. All heat banks to have a mandated maximum rate of heat loss into the space (eg

200W) when fully charged and when all baffles are closed and all fans are off, to

reduce the risk that heat would have to be vented from the room under warmer

than expected conditions.

*****



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1. Background

1.1 The BCA and Energy- and Water-efficiency

The Building Code of Australia (BCA) is becoming increasingly involved in areas ofdesign that impact on the on-going energy use of buildings. The main rationale is to

address market failures. Many of the parties who plan and construct new buildings have

a reduced incentive to incorporate design features and services which could cost-

effectively reduce lifetime operating costs, because it will be the ultimate buyer,

occupant or tenant who will meet those costs.

Because of their longevity, buildings also represent a social good. While no single

occupant or owner may be in a position to recover all the benefits of initial investments

in efficiency, the total benefit accruing to all successive owners, users and occupants

over the buildings lifetime can justify higher initial investment in efficient resource

use.

For these reasons, the BCA has incorporated a number of requirements related to the

energy-efficiency of domestic and non-domestic buildings, commencing with minimum

thermal performance standards, water heater requirements and (for non-domestic

buildings), lighting and some mechanical services. The extension of lighting standards

to Class 1 buildings and the revision of water heater provisions are also possibilities for

the future.

The impending implementation of the Australian Governments Carbon Pollution

Reduction Scheme (CPRS) is expected to lead to higher energy prices. This will

strengthen the case for the BCA to incorporate provisions which increase the energy-efficiency of buildings, because the financial costs of the failure of the market to

provide the most cost-effective level of building efficiency will be higher. This could

mean raising the stringency of standards, or adding provisions for building types and

services not yet covered.

With the establishment of the CPRS, national greenhouse gas emissions will be capped

(at levels still to be determined), so greater energy efficiency or the use of less

greenhouse-intensive form of energy in new buildings are not likely to reduce emissions

further below the cap. Reducing the demand for energy and hence emission permits,

however, will lower the adjustment costs for the economy as a whole, and financially

benefit building owners and occupants by limiting their exposure to rising energy

prices. As energy costs will increasingly reflect the greenhouse-intensity of energy

sources, the projected greenhouse impact of building services is still one of the most

useful metrics for comparing options.

1.2 This Paper

This study was commissioned by the Australian Building Codes Board (ABCB) Office

to review the case for BCA coverage of:

swimming pool and spa pool energy use (and the emissions related to that energyuse); and



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fixed electric resistance space heating.Swimming pools

This study covers both domestic and non-domestic swimming pools and spa pools. It

considers:

The estimated magnitude of energy use and related emissions; Categories of swimming pools and swimming pool equipment; Common design approaches used in swimming pools and spa pools; The need for and practicality of including provisions related to design and energy

use in the BCA.

Electric Resistance Space Heating

There may be merit in preventing the installation of electric resistance water heating in

new buildings, on the grounds of the high associated greenhouse gas emissions. The

same principles and arguments could also be applied to electric resistance in-slab and

underfloor heating, and also to fixed electric space heating, where a resistance element

heats air within a heating unit that is fixed to the building structure.

This paper review the case for, and practicality of, excluding these forms of heating

through provisions in the BCA.

1.3 Swimming Pools

The BCA defines a swimming pool as any excavation or structure containing water and

used principally for swimming, wading, paddling, or the like, including a bathing or

wading pool, or spa.

Australian Standards1define a swimming pool as follows:

A swimming pool includes any waterslide, wave pool, hydrotherapy pool or

other similar structure designed for human use, other than

(a) a spa pool or spa bath (unless part of the pool system); or

(b) a tidal pool or other similar structure where water flows in and out according

to the operation of natural forces.

A spa pool is defined as:

A water-retaining structure designed for human use

(a) that is capable of holding more than 680 litres of water; and

1These definitions are used in a number of Standards, including the forthcoming Performance ofElectrical Appliances Swimming Pool Pump-Units(currently DR 8632).



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(b) that incorporates, or is connected to, equipment that is capable of heating any

water contained in it and injecting air bubbles or water into it under pressure so

as to cause water turbulence.

Domestic swimming pools fall within Class 10 of Volume 2 of the BCA: non-habitable

buildings and structures. At present BCA Volume 2 covers access arrangements forswimming pools (ie enclosures and gates) and measures to avoid the entrapment of

persons in the water recirculation system.

Swimming pools and spa pools that are parts of non-domestic buildings (eg Class 2 or

3) are covered by Volume 1 of the BCA, which covers access arrangements, measures

to avoid entrapment of persons in the water recirculation system, and drainage and

disposal of water. An aquatic centre could be a stand-alone Class 10 structure, or could

consist of one or more swimming pools within a Class 9 (Assembly) building.

Swimming pools are energy- and water-intensive structures. Where domestic

swimming pools are installed they usually represent the highest single consumer ofelectricity in the household. Pools and spas in hotels typically account for 4% to 8% of

the total building energy use, and in apartment buildings they typically account for 10%

to 20% of common area energy use. Aquatic centres are among the most energy-

intensive of building types, with energy per floor area typically 5 times that of office

buildings (Carbon Trust 2008).

These statistics indicate that including the energy use or energy-efficiency of swimming

pools in the BCA deserves consideration.



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2. Domestic Swimming Pools

2.1 Number, and type of pools

The ABS reports that in 2007 about 945,000 Australian households (11.7% of the total)had a swimming pool (Figure 1, Figure 2). Swimming pool ownership is projected to

rise to nearly 14% by 2020, by which time there would be about 1.24 million pools

(EES 2008). The rate of pool ownership is highest in the warmer parts of Australia

(Queensland, NT and WA) and lowest in the coolest parts (Victoria, the ACT and

Tasmania). The rate of pool ownership in NSW appears to be falling slowly, although

the State still has more pools than any other (Figure 3).

A small proportion of swimming pools have an inbuilt spa pool, ie one that shares a

water recirculation system with the main pool. Separate or stand-alone spa pools are

also becoming more common. About 1.4% of homes had a stand-alone spa pool in

2007, and this is projected to rise to about 1.7% on 2020.

The distinction between swimming pools and spa pools are not always clear. In some

cases householders who would otherwise have installed a swimming pool are now

installing spa pools, because declining block sizes and larger house floor areas limit the

land area available for pools. Smaller swimming pools (and larger spa pools) are

sometimes fitted with powerful swim jet pumps which create sufficient water flow for

swimming on the spot.

Although swimming pools are generally larger (averaging about 50,000 litres) there are

now spa pools of up to 25,000 litres, about the same volume as small swimming pools.

About 88% of swimming pools are in-ground, while the great majority of stand-alonespa pools are above ground (BIS 2006). About three quarters of in-ground pools are in-

situ concrete and the rest fibreglass; usually rigid liners brought to site and buried.

Above-ground swimming pools may be constructed using flexible liners, or brought to

site as rigid assemblies. Above-ground spa pools are usually factory-made assemblies

complete with pumps, heaters and decorative external cladding.

Most domestic swimming pools are installed some time after the construction of the

dwelling. Two thirds of pool owners reported having made the decision to install their

pool, while a third reported that it had come with the house (BIS 2006).

Constructed swimming pools or spa pools are usually subject to local government

planning approval, which represents a point at which BCA compliance could be

enforced. However, council requirements vary for stand-alone spa pools brought to site

as complete assemblies they may be listed as a complying development, exempt

development or not specifically mentioned at all.2 Therefore the full effectiveness of

any BCA provisions related to stand-alone spa pools is subject to uncertainty.

2Swimming Pools and Spas Association of NSW (SPASA), personal communication, January 2009.



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0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

%ofHouseholds,

Australia

With separate

spa pool (calc)

With swimmingpool (calc)

With swimming

pool (ABS)

Figure 1 Historical and projected ownership of swimming pools, Australia

0

200

400

600

800

1000

1200

1400

1600

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

Numberofpools('000) Stand-alone s pas

Swimming poo ls -

with spas

Swimming poo ls -

no spas

Figure 2 Number of swimming pools and stand-alone spas, Australia



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0%

5%

10%

15%

20%

25%

30%

35%

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

NSW

Vic

Qld

SA

WA

Tas

NT

ACT

Aus t

Figure 3 Ownership of swimming pools by State

0

500

1000

1500

2000

2500

3000

3500

4000

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

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2014

2016

2018

2020

GWhperyear

Useful ene rgy (all form s) for

heating separate spas

Gas (delivered) for heati ng

pools/inbuilt spas

Separate spa standby

Separate spa pumps

Pool standby and timers

Inbuilt spa pumps

Chlorine cells

Solar heater pumps

Filter pumps

Figure 4 Energy use of domestic swimming pools and spa pools



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2.2 Energy and Water Impacts

The main uses of energy in swimming pools and spa pools are:

Filtration pumping: about 90% of swimming pools have a filtration pump whichoperates for several hours each day as long as the pool is filled. Most users extend

pump operating hours during the swimming season and shorten them during the off-

season.

Sanitisation: about 60% of all pools (and the great majority of new pools) have anelectrolytic cell which breaks salt added to the water down to free chlorine. A small

proportion of pools use other means of automatic sanitisation such as chlorine

dosers, and the remainder rely on manual dosage of granular or liquid chlorine.

Water heating: about a third of all swimming pools (and all spa pools, by definition)have some form of heating. The most common form of heating for swimming poolsis solar water heating, which uses energy for pumping (unlike solar domestic hot

water, there is no boosting). The most common form of inbuilt heating for smaller

spa pools is electric resistance heating, and larger spa pools often use natural gas

water heating.

Other energy uses include spa jets and swim jets (generally used only when the pool is

occupied), timers and control gear, underwater lighting and maintenance uses such as

pool cleaning. Most cleaning devices rely on the pressure of the water flow though the

filtration system, but about 3% of swimming pools have separate cleaners with their

own motors.

It is estimated that in 2008 swimming pools and spa pools accounted for about 3.3% of

total household electricity use: more than clothes dryers and dishwashers combined. In

the homes with a swimming pool, it was almost always the largest single electricity

user, averaging 1,930 kWh per year, compared with 720 kWh per year for refrigeration.

The great majority of pool electricity use was for filtration pumping (Figure 4).

Dedicated pool and spa heating accounted for about 1.8% of domestic gas use. Less

than 3% of swimming pools (representing less than 0.4% of households) have gas pool

heaters, but these tend to be very large energy consumers. The breakdown of heating

energy use in stand-alone spa pools, or the share that comes from inbuilt heaters as

distinct from dedicated external heaters or from general domestic water heaters is notknown.

Swimming pools and spa pools are significant consumers of water. Swimming pools

are rarely emptied completely, but they are subject to water loss through evaporation

and have to be topped up regularly in hot weather. Water is also lost to the drain during

the filter cleaning and backwashing process. A typical 50kl swimming pool in

Melbourne may need 20 to 30 kl of top-up water in a typical year in hotter parts of

Australia, more than the full volume of the pool will be lost each year (GWA 2006).

Evaporation can be reduced by partially screening the pool from wind or by covering

the pool when not in use. About 14% of pools have a cover, but half the owners report

that they rarely or never use it (BIS 2006).



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Spa pools are much smaller and generally lose very little water to evaporation, either

because they stand empty or, if they are left full, they are often covered to conserve

heat. However, many are emptied and refilled on a regular basis. BIS (2006) reported

that spa pool owners refilled their pools over 60 times per year on average. Even if the

smaller spas were refilled more frequently than the larger ones, annual water use per spa

could well be over 100 kl per year, or twice the volume of a full size swimming pool.

2.3 Elements of energy use

Pumping

Most of the electricity used in swimming pool operation is for pumping water through

filters or through solar collectors. Separate pumps may also be used for pool cleaners or

to circulate water through features such as waterfalls, but these tend to be required only

for short periods.

The keys to reducing the pumping energy use of a pool are:

Design the pool to minimise resistance to water flow. In general, this means usinglarger diameter pipes and fewer and more gradual bends. The choice of filter can

also be important: cartridge filters have less design flow resistance than sand filters

and are easier to clean, so are likely to be kept in a condition of lower flow

resistance. Preliminary cost-benefit modelling indicates that substituting a cartridge

filter for a sand filter is cost-effective, and saves 80 to 90 kWh per year. Changing

to 50mm piping and 135rather than 90bends, or larger radius curves, saves

between 60 and 250 kWh per year, depending on the filter and the poolconfiguration.

Matching the pump characteristics to the pool: the ideal is to turn the pool over (iecirculate the entire volume) at least once per day, and doing this at low flow rates

uses less energy per litre pumped than at high flow rates. Most pumps are single

speed, but there are two speed pumps which default to the lower speed for normal

pumping, but can be used at high speed for cleaning or backwashing. Variable speed

pump controllers which factor in the condition of the filters and the time needed to

sanitise the pool have also been introduced, but are expensive.

Use the most energy-efficient pump-unit of the models suitable for that particularpool.3 Standards Australia is currently developing a method of test for pool pump-units and a rating method to indicate relative energy efficiency, using the same star

rating label format as is used for household appliances.4

3A pump-unit is an electric motor coupled to a hydraulic pump. The energy efficiency of the unit

depends on both the efficiency of the motor and the efficiency of the pump, but can only be accurately

determined when the complete pump-unit is tested under a hydraulic load.4The standard, being developed by Committee EL-015-25, is expected to be published in the first half of2009.



17/40

Sanitisation, timers and controllers

Most pool pumps, sanitisers and cleaners are operated by timers or controllers, which

have a small standby power consumption. Electrolytic cells and chlorine dosers

themselves have relatively low energy use (typically 150-200W for a cell, compared

with about 750-1,500 W for a filtration pump). However, the cell cannot operatewithout a flow of water, so pump operation is sometimes extended for sanitisation

purposes, even after there has been sufficient circulation for the filter to remove solids.

Heating

About 31% of swimming pool in NSW, Vic, Qld, SA and WA have some form of

heating, ranging from 75% in Victoria to 17% in WA (BIS 2006). The popularity of

heating appears to be growing: over half the pools completed within the past 2 years

report some form of heating, compared with about a quarter of older pools.

The main forms of heating installed in swimming pools up to 5 years old are:

Solar (over 90% of pool heating installations): this is the most energy-efficient formof pool heating, because no thermal input is required, only pumping energy. It is

more energy-efficient to have separate pumps for the filtration and the solar heating

circuits, and over three quarters of installations use a two-pump system. In the rest,

the energy use of the main filtration pump can be greatly increased because it would

need to be oversized to circulate the water through the solar collectors, and because

the operating hours would be extended beyond filtration needs.

Gas (about 7% of pool heating installations): these are typically large recirculatinginstantaneous water heaters with inputs ranging from 58 MJ/hr (16 kW) to about430MJ/hr (120 kW) compared with 80 to 200 MJ/hr for domestic instantaneous

gas water heaters. At present there are no energy labelling or minimum energy

performance standards for gas pool heaters, but the scope for these is being

investigated by the government Equipment Energy Efficiency (E3) program.

Electric heat pumps (about 3% of pool heating installations).Electric resistance pool heaters are also available (typically 36-40 kW, 3-phase)

although now rarely used in domestic installations.

Solar pool heaters operate in a different way from other pool heaters because their

delivery temperature is limited to about 38C and this is only achieved during the

warmer months, compared with 60-80C at any time for other heaters. They can extend

the summer swimming season (especially when used with a pool cover) but do not

enable year-round swimming.

Stand-alone spa pools are all heated. Small to medium spas usually have a single phase

electric resistance heater up to about 5 kW on the filtration circuit. Larger spas may be

connected to an external recirculating gas pool heater. Smaller spas may be filled from

non-recirculating external water heaters such as a domestic gas instantaneous heater

installed for the purpose, or from the general house supply, in which case the energy

efficiency of the water heating will be determined by the domestic water heater.



18/40

Non-recirculating water heaters add new hot water to the spa, so if there is water in it

already some will have to be wasted, along with any heat and chemicals it may still

contain. In any case, the better insulated the spa and its cover, the more heat will be

retained until the next use, so less heat (and less water) will need to be added.

2.4 Standards and levels of efficiency

There are no accepted measures or standards of overall energy performance for

domestic swimming pools. Performance can vary significantly: a field trial which

swapped several pumps between several pools found that filtration pumping energy

varied from 2.9 to 12.1 kWh per 50,000 litres pumped, with most of the variation due to

the owners settings and preferences (solar hot water pumping and chlorinator energy

also varied). For the same pool, energy use could vary from 2.2 to 13.4 kWh per 50,000

litres pumped, under different pumps and settings. The lowest energy requirement was

for a dual speed pump operating at the lower speed.

Therefore there is no basis to adopt energy design standards for entire swimming pool

systems, or to test whether those standards are achieved in designs or even in post-

construction operation.

It is however possible to set performance standards for selected pool components, and

to require design features which are known to lower energy use in operation. This is the

approach taken in the CaliforniaEnergy Efficiency Standards for Residential and

Nonresidential Buildings (see extract at Appendix 1).

It is also being used to some extent in Australia. The BASIX scheme in NSW, for

example, requires a BASIX certificate for swimming pools and/or spas with a combined

volume of 40,000 litres or more. The applicant must enter data on volume, location

(indoors/outdoors), method of water heating if any, and whether outdoor pools are

shaded or equipped with a pool cover. Electric resistance heating is not permitted for

swimming pools.

The certificate may carry requirements such as:

A pool pump timer must be installed (California also has this requirement, but setsadditional capabilities for the timer);

A spa pump timer must be installed; A spa cover must be installed (California also has this requirement, with specified

insulation values where electric resistance heating is used);

A rainwater tank must be installed for topping up the pool (there must be a rainwatertap within 10m of the pool and/or spa); the volume of the rainwater tank (if

required) depends on the nominated roof area draining to it, and whether a pool

cover and shading have been nominated.

Californias swimming pool requirements go considerably further than BASIX, in that

they impact on the actual hydraulic design of the pool, pump efficiency, pump control

strategy and heater efficiency:



19/40

The pool must be designed for less than a maximum flow rate: this is intended tomake the hydraulics compatible with lower power and lower speed pumps or modes

of operation, which are more energy-efficient.

Pumps should be multi-speed (with default to lowest speed) or separate auxiliariesshould have separate pumps: this is intended to avoid large, high power pumpsoperating at part loads well below their optimum efficiency point. Auxiliary pool

loads that require high flow rates such as spas, pool cleaners, and water features,

should be operated separately from the filtration to allow the filtration flow rate to

be kept to a minimum.

Electric resistance heating may not be used for pools except in conjunction withsolar or recovered heat, or with spa pools which meet specified levels of thermal

insulation.5

Only those pool pumps, gas pool heaters and heat pump pool heaters may be usedwhich are registered as meeting California appliance efficiency standards.

Where solar heating is not installed, connections shall be installed to allow for thefuture addition of solar heating equipment.

The issues which the California regulations seek to address are also present in Australia.

Most pool builders use 40mm pipes and 90bends, even though increasing pipe sizes to

50mm and using 135bends is the single most cost-effective way to reduce the

pumping energy needed.

Also, there is a tendency for pool builders and designers to oversize: to recommend andinstall high power, high-flow pumps rather than lower power, lower flow, lower speed

pumps. This also carries an energy penalty.

Some of the elements on which the California regulatory approach is built are also

present in Australia. An Australian Standard for testing and energy efficiency rating

and labelling of swimming pool pumps is near completion. The Standard will also

contain a minimum energy performance standard (MEPS) level which will be relatively

low, at least initially. Subject to passing a regulatory impact assessment, it is envisaged

that the Standard will be made mandatory under State legislation, in the same way as

other appliance labelling and MEPS standards. Multi-speed and variable speed pumps

can generally obtain a higher star rating than single-speed pumps.

The Commonwealth-State Equipment Energy Efficiency Program has also undertaken

to sponsor the development of a method of test and a rating system for gas pool heaters.

2.5 Potential Role for BCA



5There are lists of complying spas, pool pumps, gas pool heater and heat pump pool heaters athttp://www.energy.ca.gov/appliances/database/excel_based_files/Pool_Products/



20/40

7. Requirements for pipe sizes and layout which reduce resistance to water flow,and so reduce the energy requirement for filtration pumping (eg 50 mm

minimum pipe diameters and gradual bends rather than 90elbows);

8. Prohibition of the use of electric resistance water heating for swimming pools.(As very few electric resistance heaters are used on swimming pool heating, thisis large a preventative measure). This leaves the alternatives of unboosted solar,

gas and heat pump water heating;

9. Prohibition of the use of electric resistance water heating for stand-alone spapools (other than single-phase electric resistance heaters built into the

recirculation systems of fully assembled stand-alone spa pools, or electric

boosting of solar water heaters). This leaves the alternatives of solar, gas and

heat pump water heating;

10. A requirement that all heated spa pools meet a specified level of thermalinsulation, and be fitted with removable covers that also meet a specified level

of thermal insulation. This should apply to both stand-alone and constructed spa

pools, if these can be covered by the BCA (if not, appliance energy efficiency

standards should be developed for stand-alone spas);

11. A requirement that all swimming pools equipped with heating (of any type) be

fitted with a removable pool cover, whether the pool is indoors or outdoors;

12. A requirement that all swimming pools and spa pools be installed with one or

more user-adjustable timers or other control devices which limit or manage the

hours of pump operation. (As very few pumps are installed without timers, this

formalises prevailing practice).

There may be a case in future for including the following provisions in the BCA:

10. Minimum energy efficiency levels for pump-units, that may be higher than the

general MEPS levels adopted for those products. This should be considered

once mandatory energy labelling and MEPS is implemented for pump-units, and

sufficient information is collected on the sales-weighted energy-efficiency of

pump-units installed in new pools;

11. Minimum energy efficiency levels for gas pool heaters, that may be higher than

the general MEPS levels adopted for those products. This should be considered

once mandatory energy labelling and MEPS is implemented for gas pool

heaters, and sufficient information is collected on the energy-efficiency of pool

heaters units installed in new pools;

12. Requirements for pump-unit configurations and control strategies to limit power

and rates of flow and to prevent the installation of over-sized filtration pumps

which would operate at low efficiency much of the time (as in California).

These issues should be reviewed from time to time as information accumulates.



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3. Shared and Public Pools

3.1 Type and number of pools

Shared pools are privately owned pools which can be used by any authorised person (as

distinct from domestic pools which are owned by individual households). Typical

examples are swimming pools in the common areas of apartment buildings or hotels,

where the condition of use may be tenancy of an apartment or being a guest at the hotel.

Public pools are open to all users. They are often owned and operated by local

government (although leasing to managing agents is becoming more common). Pools

in this category may range from single unheated outdoor swimming pools to multiple

Olympic standard pools enclosed within large buildings, or aquatic centres.

As public pools are often used for organised or school sporting events they are oftenconfigured as full-length (50m) or half length (25m). A full size Olympic swimming

pool is exactly 50m long, 25m wide and at least 2m deep, giving it a water volume of at

least 2,500,000 litres, or 50 times the volume of the average domestic pool. However,

many public 50m pools are narrower typically 16 to 20m.

The ABS does not appear to have any data on the number of shared or public pools in

Australia. Sydney Water (2005) estimates that there are about 100 public swimming

centres in the Great Sydney area, apart from pools in hotels, clubs, fitness centres or

apartment buildings. Given that Sydney has about 20% of the national population, this

would indicate about 500 public pool nationally. However, many smaller centres would

have a pool, so the number of pools per person outside the capital cities would be muchhigher. At a rough guess there could be 1,000 to 1,500 public pool complexes in

Australia, many with more than one swimming pool.

In 2008 there were 6,200 hotels, motels and serviced apartments with 5 or more rooms

in Australia (ABS 8635.0). If say half of these had a pool that would be 3,000 pools.

There are no direct data on the number of apartment buildings, let alone the proportion

of those with a swimming pool. However, the Census reports the number of apartments

located in buildings of 1 to 2 stories, 3 stories and 4 or more stories. Assuming an

average of 10, 30 and 60 dwellings respectively for each of the above building types

would indicate about 60,000 apartment buildings of 1 to 2 stories, 10,000 of 3 storeys

and over 5,000 of 4 or more storeys. If, say, 1 in 3 of the high rise apartments and 1 in

20 of the rest had pools, that would be another 5,000 pools..

With clubs, fitness centres etc there could possibly be a total of 8,000 to 10,000 shared

swimming pools in Australia.



22/40

3.2 Energy and Water Impacts

Shared and public pools use energy for the same main purposes as domestic pools:

water filtration, sanitisation and heating. However, the amount of energy used per pool

is much higher because average water volume is higher, bather loads are high and the

sanitisation standards for public pools have to meet public health regulations.

For example, shared and public pools are all covered by the Public Health (Swimming

Pools and Spa Pools) Regulation 2000under theNSW Public Health Act 1991, which

states that:

The occupier of a swimming pool or spa pool to which this Regulation applies

must not allow a person to use the water in the pool unless the water in the pool

is disinfected in such a way as to prevent the transmission of scheduled medical

conditions to the other users of the pool.

The Guidelines issued by the NSW Department of Health state that:

all treated water public swimming pools and public spa pools shall be equipped

with an effective water circulation system, filter and continuous disinfectant

dosing control system. Continuous dosing means the use of a metering device to

feed a chemical at a relatively constant rate (NSW Health 2006).6

The Guidelines also specify the periods in which the entire water volume must be

turned over. In effect public and shared pools need to be sanitised and filtered

continuously while open to the public, as distinct from domestic pools, where filters and

sanitisers only need to operate 15% to 25% of the time, even in the swimming season.

Public pools are also far more energy intensive than domestic pools in that most are

heated, many are within buildings which need heating, ventilation and air conditioning,

and many have user amenities with their own energy and water requirements.

The energy and water use of public and shared swimming pools is a matter of

considerable interest to their owners, because the operating costs and utility charges can

be very high. However, comparisons are difficult to make, because almost every study

reports different measures and benchmarks. Some report energy for the entire

swimming centre including amenities and non-swimmer areas, some for the pool hall

only, some for the pool only (with pumping energy and water heating energy sometimescombined and sometimes separately reported).

Table 1 summarises the energy use guidelines from a UK publication (for an entire

aquatic centre ). As the water temperatures are much the same in all public pools, and

the HVAC requirements are driven more from the need to manage condensation from

the pool rather than by external temperature conditions, the energy use of a similar

indoor pool in Australia should be roughly similar.

6The Regulations state that: It is a defence to a prosecution for an offence against this Regulation if the

defendant satisfies the court that the act or omission constituting the offence was done in compliance with

the Guidelines for Disinfecting Public Swimming Pools and Spa Poolspublished by the Department ofHealth as in force from time to time.



23/40

Table 1 Energy budget and energy saving options for a typical small public indoor

aquatic centre

Electricity

kWh/m

2

Heating

kWh/m

2

Total

kWh/m

2

Share of

saving

kWh/yr

(a)Typical pool

Good practice

237

152

1336

573

1573

725

1494350

688750

Potential saving 36% 57% 54%

Better building insulation

Better ventilation management

Improved pool pumps

Regular use of pool cover

Improved Lighting

Operation & scheduling changes

0

-25

-29

-8

-16

-7

-51

-481

0

-145

0

-86

-51

-506

-29

-153

-16

-93

6%

60%

3%

18%

2%

11%

-48450

-480700

-27550

-145350

-15200

-88350

Total potential energy saving -85 -763 -848 100% -805600

Source: UK Energy Consumption Guide 78 (2001) One heated pool 25x12 m surface (a) Total floor area

of centre is 950 m2.

The information about water and energy use in public pools in Australia is rather

limited, although several studies currently under way should improve this situation

during 2009.7 Information about shared pools in hotels and apartment buildings is even

more limited. EnergyAustralia has reported detailed energy use for two high rise

apartment block with pools and spas in Sydney (Table 2). The total annual energy use

in Building A was about 290,000 kWh/yr, or about 5% of total common area electricity

use and 15% of common area gas use. The total annual energy use in Building B

approached 244,000 kWh/yr, or about 27% of total common area electricity use.

Table 2 Typical energy budget for small public indoor pool centre

Electricity

kWh/yr

Gas heating

kWh/yr

Total

Building A Swimming pool

Sauna

Spa

50000

2778

27778

208333

0

0

258333

2778

27778

Combined 80556 208333 288889

Building B Swimming pool

Spa

122222

102778

0

0

122222

102778

Combined 244444 0 244444

Source: Derived by author from EA (2005)

Where present, pools obviously account for a significant proportion of common area

energy use. According to the Commonwealth Department of Resources, Energy and

7The Sydney City Council is collecting energy and water consumption data for all of its aquatic centres;this should be available in March 2009 (personal communication, January 2009). Sydney Water has

commissioned 11 energy and water audits of aquatic centres (The Conserver, October 2009) and is usingthe data to compile benchmarking Guidelines, to be published in mid 2009 (personal communication,

January 2009). The Victorian Aquatic Industries Council has a grant from the Smart Water Fund to carryout a study of water (but not energy) use in 75 aquatic centres in Victoria. The results should be availableduring 2009 (personal communication, January 2009). .



24/40

Tourism Energy Best Practice program, pool energy accounts for between 4% and 8%

of total energy use in hotels.8

3.3 Elements of energy use

In general, the same energy and water uses are present use in public pools and the

buildings which house them as for domestic pools, but on a much larger scale and

designed for high intensity of use.

There are however several important differences in design approach:

Public pool design tends to involve engineers, architects and other buildingprofessionals, whereas domestic pools tend to be designed by builder-packagers;

Many clients commissioning public pools are well aware of the high operating costs,and will instruct designers accordingly, whereas very few domestic pool clients are

aware of this;

Public pools must meet a range of stringent and regularly enforced health standards,some of which are quite prescriptive in terms of sanitisation and water turnover,

whereas the standards for domestic pools are in effect advisory and not enforceable;

Many public pools are housed in buildings, or parts of buildings, which have highservice requirements and energy use of their own and interact with the general

building services in complex ways (some of which offer opportunities, eg use of

waste heat). Very few domestic pools are in this situation.

Pool water management and conditioning

Public pools have much larger pumps than domestic pools. The Australian Standard for

energy efficiency of swimming pool pumps applies to all single phase pump-units

intended to be used in the operation of swimming pools and spa pools, but it will not

cover the 3-phase pumps-units, which tend to be used in public pools. However, the 3-

phase electric motors themselves are subject to MEPS.

Most public pools are heated to between 26C and 28C. Public spas are limited to no

higher than 38C. This increases the rate of both water and heat loss due to

evaporation.

Unlike domestic pools, where the management objective is to lose as little water as

possible in normal use, public pools have to add new water continually: the current

benchmark is about 40 to 60 litres per visitor per day (Sydney Water 2008).

http://www.ret.gov.au/energy/Documents/best%20practice%20guides/energy_case_studies_rydgescapitalhill.pdfand other case studies.


8


25/40

Heating and Ventilation of Pool Buildings

According to the UK Carbon Trust (2008), the control of evaporation from the water is

a function not normally encountered in standard heating, ventilation and air

conditioning (HVAC) systems, and can therefore be misunderstood by designers and

operators.

The ventilation system is normally the primary (or only) means of:

Controlling the pool hall air quality, temperature and humidity so as to reduceevaporation from the pool and prevent condensation (and, potentially, corrosion

damage).

Maintaining comfortable environmental conditions for different occupants. Removing chlorine and other contaminants from the air.In colder climates, a large amount of useful heat is lost by ventilation of the pool

enclosure, and recovery of that heat is often a priority. In Australia however, heat loss

through ventilation may be necessary to cool the pool enclosure, so high air change

rates may be an advantage rather than a liability, at least for parts of the year. It also

means that exhaust air, even though typically 1C higher than the pool water

temperature, may still be cooler than the outside air, so the heat exchange may need to

work in the opposite direction (ie to cool rather than heat incoming air).

User amenities

Almost all public pools have locker rooms, toilets and showers for bathers. These can

have significant HVAC, lighting and hot water demands of their own. There may also

be administration areas and (less service-intensive) circulation areas, storage and plant

rooms. Public pools may also have adjacent gym areas or other indoor sports courts,

public sitting areas, spectator areas and kitchen and catering facilities. To the extent

that these spaces and functions are all adequately covered by provisions in the BCA,

there are no special requirements when integrated with or attached to public pools.

However, the design of a multi-function building which includes a pool can give rise to

complex interactions of services which can present both problems and positive designopportunities with regard to energy and water management.



26/40




13. Definition of a distinct class of non-domestic swimming pools and spa pools

that correspond to the definition of public pools used in health regulations, eg

swimming pools and spa pools to which the public is admitted, whether free of

charge, on payment of a fee or otherwise, including swimming pools and spa

pools:

(a) to which the public is admitted as an entitlement of membership of a

club, or

(b) provided at a workplace for the use of employees, or

(c) provided at a hotel, motel or guest house or at holiday units, or similar

facility, for the use of guests, or

(d) provided at a school or hospital,

but not including swimming pools or spa pools in private residential

premises.

14. Prohibition of the use of electric resistance water heaters for public swimming

pools or spa pools. The alternatives would include solar (unboosted, electric-

boosted or gas-boosted), gas, heat pump or waste heat;

15. A requirement that all public spa pools be fitted with insulating covers and havea minimum level of thermal insulation;

16. A requirement that all public swimming pools equipped with heating (of any

type) be fitted with a removable pool cover, whether the pool is indoors or

outdoors;

As nearly all public pools would have special design requirements which are likely to

involve engineers or other specialists, general design provisions relating to pipe sizes or

controls which are appropriate for domestic pools are not appropriate for public pools.

There are at present no general Australian energy or water performance standards forpublic pools, for buildings housing public pools (eg Class 9) or the parts of buildings

housing public pools (eg parts of Class 2 or 3). There are several projects under way to

gather data on which such performance standards could be based.

Even if performance standards were developed, it would also be necessary to develop

methods of predicting performance so that compliance with those standards could be

established. It may then also be possible to establish deemed to satisfy provisions: eg

the recovery of heat from moist are ventilated from the pool hall.

There may be a case for including such provisions in the BCA in future, and these

issues should be reviewed from time to time as information accumulates.



27/40

4. Fixed Electric Resistance Space Heating

4.1 Types of Fixed Electric Resistance Heating

Electric resistance heating is currently the most greenhouse gas-intensive means of

space and water heating, even though it is close to 100% efficient at the point of

conversion. This is because the great majority of electricity generated in Australia is

from the combustion of coal, leading to high emissions and low conversion efficiency at

the power stations. Despite the CPRS, the average emissions intensity of electricity

supplied in Australia is still projected to be about 75% of todays levels by 2030

(Treasury 2008).

Table 3 illustrates the typical emissions per unit of useful energy output from the most

common means of space heating. Although natural gas and LPG combustion is less

efficient than electricity at the point of use, the greenhouse gas-intensity is so muchlower that it still has a greenhouse advantage. The use of heat pump technology brings

the greenhouse intensity of electric heating much closer to that of gas or LPG.

Table 3 Typical emissions per unit of heat output, space heating

Typical

efficiency

kg CO2-e/GJ

delivered(a)

kg CO2-e/GJ

useful energy

Electric Resistance

Electric Heat Pump

Natural Gas combustion

LPG combustion

Wood (controlled combustion)

100%

280%

75%

75%

60%

278

278

64

67

14(b)

278

99

85

89

23

(a) Typical full fuel cycle emissions factors for energy delivered and converted. (b) CO2from renewablefuels not counted only CH4and N2O emissions.

There are many possible applications of electric resistance heating in buildings. This

paper is only concerned with electric resistance heaters intended to maintain a

comfortable thermal environment for the occupants of a Class 1 or buildings (or the

residential parts of other building classes), as distinct from:

electric resistance water heaters, which may eventually be covered in other parts ofthe BCA; and

specialised electric resistance heaters designed for non-residential applications, suchas providing local heating for workers within otherwise unheated industrial spaces

(industrial heaters), or blowing warm air across open doorways to prevent leakage

of conditioned air in retail buildings (air curtains).

The definition may need to be further limited to cover stand-alone devices which rely on

electric resistance alone, rather than where electric resistance is used in association with

heat pump technology (eg as booster elements) or with other fuels (eg dual-energy gas

and electric heaters), or as spot reheaters in air conditioning ducts.



28/40

Electric resistance heaters have the advantage of flexibility of location, since no pipes or

flues are necessary. The main disadvantages are high running costs and high

greenhouse gas-intensity. Electricity prices are expected to increase more than other

energy forms as the CPRS begins to influence the energy market, so the running cost

disadvantages will increase.

Electric heaters up to 2.4 kW output can be plugged into a power-point, whether or not

the heater is fixed to the structure or portable. Larger capacity units need fixed wiring,

so need to be installed by a qualified person. The effectiveness of BCA coverage of

plug-in fixed electric heaters is likely to limited, because any provisions can be easily

circumvented (either by the builder or the occupant) by fixing the heaters after

completion and plugging them in to power points pre-positioned for that purpose.

The relatively low capital cost of fixed plug-in electric resistance heating can make it

attractive to project home builders. An even cheaper option is to provide no fixed

heating at all, and let the eventual occupants install portable electric heaters, or any

other type, at their own cost. This is common practice in NSW and Queensland, but isnot generally acceptable to home buyers in the States where natural gas heating is

popular (Figure 5).9

Alternatively, buildings in warmer areas may be equipped with air conditioning, which

will almost always have a reverse cycle heat pump heating capability (cooling-only air

conditioners have disappeared from the market). While this is a relatively efficient form

of electric heating, it comes at the cost of introducing cooling, which may be otherwise

unnecessary and which may contribute to summer peak demand on the supply system.

Homeswith

thisformofmainheating

100.0%

90.0%

80.0%

70.0%

60.0%

50.0%

40.0%

30.0%

20.0%

10.0%

0.0%

NSW Vic Qld SA WA Tas NT ACT Aust

Other

Wood

Gas

Electric - heat pump

Electric - nond ucted

Electric - slab

Electric - ducted

Figure 5 Types of main heating in Australian homes, 2008

9note that most nearly all gas heaters in the NT would be LPG).



29/40

The proportion of existing dwellings and other buildings with fixed electric resistance

heating is not known. Of the main heater types which the ABS surveys (ABS 4602.0)

only electric slab heating and electric ducted heating are definitely fixed and

resistive. Together they account for less than 4% of main heaters. The non-ducted

electric heater category is resistive, but not necessarily fixed. In fact, the great majority

of non-ducted electric heaters in NSW and Queensland are portable, because therelatively low demand for heating in most parts of those States means that multiple

plug-in heaters are adequate. Only in Tasmania and the ACT is it likely that a

significant proportion of non-ducted electric main heating is fixed and hard-wired.

Whatever the form of main heating, many homes will use electric resistance heaters for

secondary heating. For example, a household with an open plan living area served by

a gas or wood space heater will often use electric resistance secondary heaters in

bedrooms and bathrooms. As secondary heaters tend to be 2.4 kW or less, they can

usually be plugged into a standard power-point, whether or not they are physically fixed

to a wall. In fact, some manufacturers offer the same heater bodies in fixed or portable

configurations.

Electric resistance heaters can be broadly classified into three main categories:

Space heaters: these are intended to circulate heated air evenly throughout a space,often in living areas, where higher temperatures are usually desired. They generally

incorporate a forced convection fan as well as the resistance elements;

Background heaters: these rely on natural convection or conduction (contact withthe heated surface, especially floors) to provide background heat in circulation

spaces such as passageways or in bedrooms, where lower temperatures are usually

required than in living areas;

Specialised or local heaters, eg heated towel rails, downward-pointing fan heatersdesigned for bathrooms, or radiant heaters which are intended to heat only the

persons within range of the heater.

Table 4 gives some examples of each type.

Underfloor (slab) heating

Embedding heating systems in the floor is common in cold countries, where homes areheated more or less continuously over the winter, but less common in Australia.

Nevertheless, the local market offers several electric resistance heating systems

designed for embedding in concrete floor slabs, or in the grout layer between the slab

and floor tiles (or under timber, carpet or other surface finish). As the heated air rises

and circulates through the room by natural convection, no other form of heating is

necessary.

The typical installed power density of heating elements is about 100-120 W/m2in living

areas and bedrooms, and 150-200 W/m2in bathrooms, swimming pool surrounds or

other places where people walk barefoot. A typical 4m x 5m living area would have a

total embedded wattage of 2.4 kW, comparable to typical fan or column heater.



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Depending on the heat loss from the space, the average operating power usually falls to

a third to a half of the maximum power, once the slab is fully heated.

Slab-embedded heaters can operate as storage heaters, taking power during parts of the

day or night when electricity is cheaper, and gradually releasing the stored heat at other

times. Under-tile heaters operate more like day-rate space heaters, because the intervalbefore heat is transferred to the space is much shorter. Underfloor heaters in bathrooms

are typically controlled by time clocks to match the most intensive periods of daily use.

All modern electric slab heaters have thermostats, so the power can be regulated or

switched once the space reaches a preset temperature. Larger installations also tend to

be zoned, so rarely occupied rooms need not be continuously heated.

Hydronic heating, in which the heating medium is circulating water or other fluid, may

also be use for underfloor or in-slab installation. The heat source may be any

combustion heater (gas, LPG or wood ) or even an electric resistance water heater, and

any of these may be combined with a solar pre-heater. Various configurations arepossible the heater may serve the underfloor system only, or domestic water heating

and possibly convection air heating as well. Hydronic systems are more complex and

expensive to install and maintain than electric slab heaters, but they may cost less to

operate. However, accurate temperature control and zoning may be more difficult for a

hydronic than an electric resistance system, so a poorly designed and controlled

hydronic system may not have much running cost or greenhouse advantage over a well

designed electric resistance system.

Heat banks

Heat banks work in much the same way as under-slab electric resistance heaters, but

instead of the floor slab the thermal store consists of bricks purpose-made to have a high

thermal storage capacity. These are surrounded by insulation and contained in a metal

cabinet which is usually placed on the floor in the space to be heated (wall fixing to

masonry is possible, but the cabinet can weigh 100-200 kg).

The heater operates as a combined background and convection space heater. The

main difference from other electric heaters is that the heat bank heats the thermal store

at times of low electricity price and then releases the stored heat gradually into the

space. The rate of release is determined by the temperature differential between the

heat store and the air outside the cabinet, and the insulation value of the thermal store.

The main weakness of the design is limited controllability. It is difficult for the user (or

the controls) to project the heat requirement ahead of time, so there is a risk that a fully

charged heat bank will release too much heat the next day, or conversely if the recharge

was partial there will not be enough heat. This can be addressed by having

supplementary booster elements (possibly with the electricity charged at day rate) to

top up heat, by controlling the rate of heat transfer through the operation of fans or

baffles in the insulation, or both. However, it is not possible for a heat bank to respond

to room conditions as directly as a simple on-demand thermostat-controlled electric

heater. At worst, if there is an unexpected warm day in winter, the room windows will

have to be opened to let out the unwanted heat.



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The main advantage of a heat bank compared with conventional electric resistance

space heating is the running cost. Heat banks are in many ways a legacy of older utility

pricing strategies to develop timer-controlled off-peak loads, sometimes as a counter

to the spread of natural gas heating. It is likely that these strategies will increasingly be

replaced by time of use metering and dynamic pricing. This should increase the average

electricity price to heat banks (and possibly reduce the average price to on-demandelectric heaters), so at some point the running cost saving may no longer compensate for

the extra capital costs and lower controllability. However, heat banks and other heat

storages will still be of value to utilities, especially as the share of variable renewable

energy sources in the generation mix increases.


Table 4 summarises the configurations and functions of domestic electric resistance

heating discussed above. The shaded areas indicate where coverage by the BCA may

be a practical option.

Table 4 Types of electric resistance heaters and potential for BCA coverage

Heating function Plug-in examples Hard-wired examples

Fixed Background Fixed Panel heaters Underfloor slab heating

Space Fixed convectors Heat banks, convectors

Local/specialised Radiant bathroom heaters Towel-rail heaters (a)

Portable Background Oil-filled column heaters NA

Space Fan heaters NA

Local/specialised Radiant NAShaded area indicates potential for coverage by BCA (a) There are also plug-in fixed towel rails.

There is little point in the BCA covering fixed heaters of 2.4 kW or less, since these

are no more part of the building fabric than a shelf or a toilet roll holder. If the BCA

were to prohibit plug-in fixed electric resistance heaters, say, homeowners (or builders

or tradespersons) would simply fix them after the certified completion of the building

and plug them in to the power points pre-positioned for that purpose. .

The only types of electric resistance heater that could be effectively covered are:

Heaters which are part of the building fabric, eg physically integrated into the floor,wall or ceiling, rather than fixed to their surface; and/or

Hard-wired heaters, which may not be connected to the electricity supply by astandard power point, because they draw more than 10 amps, and/or require a 3-

phase supply, or for safety reasons.

These definition would cover electric slab and underfloor heating, and heat banks, both

of which are relatively rare in existing buildings, and probably even more so in new

ones. Given the small proportion of electric resistance heater uses where BCA coverage

may be practical, is there a rationale for coverage?



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It has been suggested that if electric storage water heaters are excluded from new

dwellings on the grounds of greenhouse gas-intensity, then so should electric storage

space heaters. This does not necessarily follow.

Water heaters deliver a highly standardised service (hot water) so qualitative differences

between types and energy forms are small. There is no way to distinguish water heatedby electricity, gas or solar, so long as it meets the same criteria of availability,

temperature and rate of flow, so the real differences between options are capital cost and

running cost, which in turn reflects greenhouse gas-intensity. As users have no strong