stearndale road case study 20.06 - 44 consult · the property had single glazing throughout,...

Sterndale Road

CE334

A refurbishment case study: achieving an 84% carbon saving

Sterndale Road – A refurbishment case study: achieving an 84% carbon saving (2011 edition) __________________________________________________________________________________

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Contents 1. Background ................................................................................................................... 3 1.1 Aims of the project ........................................................................................................ 3 2. Property features before refurbishment ........................................................................ 4 2.1 Pre-works testing .......................................................................................................... 5 3. Approach ...................................................................................................................... 7 3.1 Design features specified ............................................................................................. 8 3.2 Special features ............................................................................................................ 9 3.3 Construction ................................................................................................................ 10 3.4 Post-works testing ...................................................................................................... 11 4. Monitoring ................................................................................................................... 14 5. Features of the property after refurbishment .............................................................. 15 6. Funding and construction costs .................................................................................. 16 7. Closing comments ...................................................................................................... 17


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1. Background 19 Sterndale Road is a six bed Victorian family home in the largely owner occupied area of Hammersmith and Fulham. For Notting Hill Housing, this property provided the perfect opportunity to undertake a comprehensive eco-refurbishment beyond present decent home standards (see ‘headline aims’). The main partners for the project were Baily Garner and United House, who both had considerable experience in undertaking refurbishment on a range of dwelling types. In addition to this the green features specified were strongly influenced by feedback from Notting Hill’s Residents Repairs Working Party (RRWP). This is Notting Hill's first eco-refurbishment on this scale, and the performance of all features in the house will be monitored over the next two years by the University of Brighton to assess their viability for use in similar and smaller properties. 1.1 Aims of the project The main aim of the 19 Sterndale Road exemplar project was to inform the development of design guidelines and specifications for Notting Hill’s Property Services and Development Department. These guidelines will form the basis of future mass refurbishment of Victorian, Edwardian and Georgian properties. An additional aim of the project was to improve the Energy Performance Certificate of the property. The target was to increase the rating from a band G to a band B, reducing the annual running costs of the property from £2,020 to £220 as well as the carbon emissions. To achieve this aim Sterndale Road was selected as a test bed to work out which technologies and products perform best, from both from an environmental and a commercial point of view. The project also offered the opportunity to gather feedback from contractors on buildability and value of different improvement measures. The project also had to meet modern day living aspirations through the specification of cost-effective improvement measures that are easy for occupiers to get along with, reduce running costs and carbon emissions.

The flowchart above illustrates the key areas of monitoring and measurement identified by the project team.


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2. Property features before refurbishment

Internally the property was in a generally poor state of repair and décor prior to refurbishment.

The basement was not a habitable space in the dwelling and was mainly used for storage and as a secure area for drying clothes. The front of the basement suffered from dry rot, with additional signs of dampness present elsewhere in the property. All timbers where removed and replaced.

The property had single glazing throughout, predominantly sash windows, but with a casement window on the rear elevation. All of the doors were half-glazed solid wood.

Hot water was supplied by point-of-use mains gas boilers as shown above. Heating was provided by on-peak portable electric panel heaters.

SAP=13 EPC=Band G Annual running costs = £2020 Annual CO2 emissions = 12.3 tonnes Initial EcoHomes XB rating = 7


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2.1 Pre-works testing A thermographic survey and airtightness test were undertaken before improvement works commenced in November 2008. The thermographic survey helped to confirm the presence of the following building defects:

Cold areas in the lower walls of the basement (which were damp to the touch).

Heat loss in the bathroom due to the absence of insulation and the poor state of the solid brick construction (missing plaster, detached wall paper etc).

A cold spot on the internal surface of the back wall of the property, air leakage around the window and thermal bridging at the wall-to-wall junction is also clearly shown (this was present at all wall junctions in the property).

Heat loss could be seen through the solid lintels and under the roof parapet throughout the property.

This is an external thermographic image looking down onto

the flat roof. Minor gaps can be seen in the insulation within the new roof which had only recently been replaced

(this minor defect would unfortunately remain in the final project).


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The airtightness test result was 17.5 m3/m2/h @ 50Pa confirming that the existing dwelling suffered from significant air leakage, with excessive draughts around windows and doors.

Blower door rig


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3. Approach The emphasis of the approach to the project was to consider the use of materials and components that would improve overall thermal performance, lower fuel costs and carbon emissions whilst adding to the overall sustainability credentials of the property. This aim was established based upon concerns raised through the RRWP, who where involved in setting the vision, objectives and monitoring strategies for the project. The RRWP were also involved in interviewing and selecting the partner contractors and regularly made visits to the site during construction. The physical layout of the property was left pretty much unchanged, but making the basement habitable allowed the front room to be used as an additional bedroom. The living room was moved downstairs allowing the occupants to walk through a set of french doors into the back garden. The back extension was also fitted out with a new shower room. The kitchen, which was originally downstairs, was moved next to the dining room area on the upper ground floor of the property. Whilst the emphasis within this project was on practical cost effective measures, the availability of some London Development agency (LDA) funding enabled the team to carry out an element of research and development, including:

• A smart voltage management system.

• A ‘tadpole’ in the heating system. The last two items are detailed on page 10. The group also evaluated aerogel dry lining systems and the possibility of replacing existing window panes with vacuum glass panels. Whilst these items were not taken forward on this exemplar, they will be considered for the future refurbishment of Victorian flats, both void and whilst occupied. There was a wide variety of potential products to choose from at design stage, so workshops where run and each product assessed against the following criteria:

Category Consideration Performance The impact it will have on reducing the energy

requirements.

Availability The time needed for the material to arrive on site.

Maintenance/ cost in use

The operational and maintenance cost of each option.

Installation How easy is it for the builder to use/install?

Desirability Ease of operation and what impact does it have on the enjoyment of the property.

Environmental impact How the material affects the climate (manufacture to disposal).

This resulted in the improvement package as detailed overleaf being generated.


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3.1 Design features specified Flat roof • 240mm wood fibre insulation slabs to

achieve 0.15 W/m2K (the roof had been insulated and recovered within the last 4 years, and was left unchanged).

External walls • 65mm of insulation backed

plasterboard to achieve 0.32 W/m2K. Basement floor • 220mm lightweight expanded clay

aggregate to provide insulation with 55mm screed.

Windows • Laminated pine windows fitted with

double-glazed with low-E glass to achieve 1.2 W/m2K.

Heating and hot water • A-rated mains gas boiler. • Under floor heating in the basement

and radiators with thermostatic radiator valves (TRV’s) elsewhere.

• Time and temperature zone control and weather compensation.

• Twin coil thermal store (to accept solar hot water feed).

Renewables • 2x2.32m2 flat plate solar hot water

collectors which should be sufficient to meet nearly half of the annual hot water demand.

• 0.875 kWp photovoltaic array consisting of 5x210Watt peak modules.

Lighting • 100% dedicated low-energy lighting

throughout.


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Other exemplar features incorporated into 19 Sterndale Road:

• The plasterboard specified incorporated recycled paper content to improve the environmental profile of the product.

• The kitchen cabinets are constructed from fully recycled timber panels and the cabinet doors are made from a combination of recycled timber and wood certificated by the Forest Stewardship Council (FSC). The worktops are also made from recycled glass.

• All timber in the house and doors was sustainably sourced with a full chain of custody certificate (e.g. FSC/PEFC).

• Hemp was specified within the partition walls and intermediate floor to provide sound insulation.

• Linoleum flooring was used which is made of completely natural materials and is 100% recyclable.

• Water efficiency measures were also incorporated including a 6/4 litre flush toilet cistern, a 140 litre low-line bath and aerated/click stop taps to the bathrooms, WC and kitchen.

• A rainwater harvesting system was incorporated and used to provide water to the toilets only.

• Provision of multi-chamber storage bins for waste separation.

• Provision of space to allow working from home.

• Low or zero volatile organic content (VOC) eco-paints were used throughout.

• The chimney breasts were sealed, but instead of venting by incorporating a traditional louvre vent the design team incorporated vent ducts which terminated at ground level within the rear garden. This provided the necessary ventilation, but preventing unwanted heat loss.

Adaptation to climate change was also considered, and the insulation boards and plasterboard finish within the basement were fitted horizontally so that only the lower boards need to be replaced if flooding should occur (60% of the Hammersmith and Fulham area is liable to flooding).

Horizontal installation of insulation and plasterboard.

3.2 Special features As a part of the project the design team had the opportunity to install a selection of innovative technologies to identify potential energy savings. The team are closely monitoring these technologies.


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Smart voltage management system

In the UK the average voltage supplied from the national grid is 242V; however, the majority of electrical equipment used within the UK is manufactured to European standards, designed for 220V and will operate effectively down to 200V. Forcing appliances to operate at a higher voltage in the UK leads to significantly higher energy consumption, increased heat losses and a reduced life. The smart voltage management system reduces and regulates the supply voltage on the connected circuits to a set level of 220V, therefore decreasing consumption. In a domestic situation the unit is typically connected to a maximum of three socket ring circuits (32A) and two lighting circuits (6A), but not circuits with electric heaters or cookers as the appliance loads would be too high. The unit features an automatic bypass to circumvent the 220V restriction when load is continuously high.

Schematic of a tadpole

The tadpole is installed in the primary feed from the boiler. Water is pumped through the top of the tadpole and leaves though the bottom in a spiral vortex (just like water emptying out of a bath). The vortex action of the tadpole claims to remove dissolved air within the heating circuit loop, which when present makes the water slower to heat. The potential mechanism for saving energy is not clearly understood as the heat input to the dwelling to achieve a specific indoor temperature will remain the same. The effect of the tadpole on removing dissolved air when it is specified in a sealed system (as is the case in Sterndale Road) is also unknown.

3.3 Construction The standard of workmanship was monitored through regular site visits by the contract administrator, the client and the resident’s representative. To help the operatives understand the requirements an onsite induction was carried out informing them of the project objectives, key areas and what they would be monitored upon. Monitoring during the construction phase included:

• Thermal images before and after – showing for example gaps in the insulation.


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• Airtightness testing before and after refurbishment. A feature of this approach was that each operation was checked for sealing of gaps and vulnerable areas before signing off and proceeding to the next stage. This relied heavily on the diligence of the contract’s manager. To help record the lessons learned, the operatives were encouraged to complete a feedback log of what worked or did not work, including comments on the impact on efficiencies, number of trades involved and the need for specialist training or sub-contracting. Examples of the feedback include:

• The expanded clay aggregate used for the floor insulation was found to be far more efficient and easier to use. Ordinarily it would have been necessary to buy in sterilised hardcore, manhandle to the basement area and compact in layers before blinding and laying concrete.

• There was some difficulty in obtaining larger quantities of hemp insulation that was used as an alternative to mineral wool for sound proofing partition walls.

• A variety of low VOC/eco-paints were used, the contractors found that the wall paints could be applied as per standard paints, but the timber paints where harder to apply to the required standard. This led to increased costs and delay.

Informative site tours where provided during an open week for stakeholders during construction.

The design team found the mid construction open week helpful as it generated useful feedback and queries from the visitors. The design team were asked what the eco-works specifically did to the value of the building, compared before and after the work was complete. This prompted valuation advice and although the property value had increased purely due to the fact that the building had been refurbished, any increase in value due to the green "elements" was unquantifiable. This opens a whole separate debate as to how much influence energy performance certificates have on the purchaser and whether in time, potential future occupiers would expect market values and rents to be inline with the energy performance of the dwelling. At this stage the team produced an extended home user guide which provided additional information on the operation and purpose of some of the exemplar features.

3.4 Post-works testing When originally surveyed the property was in a very dilapidated state and the windows and doors on the ground floor had been boarded up. Following completion of the improvement works thermographic examination of the external elevations showed them to be noticeably colder, demonstrating that the internal insulation is having the desired effect.


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Internal insulation has helped reduce heat loss (compared to the adjoining property on the left). Heat loss through

the stone lintels has also been correspondingly reduced. Other areas of note are:

Air leakage was present around the new window and

door seals.

Reduced heat loss at the roof parapet which was a by-product of incorporating internal insulation (because the thermal conductivity of the adjoining elements are now

similar, reduced heat loss occurs at the junction).

Because thermal bridging and air leakage were not specific targets for the project most external corner and floor junctions showed heat loss which could compromise internal comfort. This could affect the temperature set point

which occupants perceive as comfortable due to the localised cooling caused by building flaws. In addition to these points the surveyor undertaking the thermographic investigation found evidence of heat loss along the junction length of the party wall which abuts the front and rear external walls. The main areas of the party wall didn’t show areas of heat loss (this was because the solid party wall is adiabatic due to the adjoining property being heated). This shows that insulation returns of at least 1.5m along the party wall to external wall junctions should have been specified to reduce heat loss.


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The post-works airtightness test result was 5.9 m3/ m2/h @ 50 Pa, this is a good result and exactly where the design team had hoped the result would fall as it is an appropriate level of airtightness for a property incorporating natural ventilation (via a combination of background ventilators and local extract fans in this case). Unfortunately the opportunity was not taken to record specific air leakage areas (e.g. using a smoke pencil) other than those captured within the thermography survey.


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4. Monitoring Both tenant behaviour and building performance is being monitored. The Centre for Sustainability of the Built Environment at the University of Brighton is monitoring and analysing usage from build to occupancy. This includes measuring electricity and gas consumption (the gas boiler and individual circuits are being measured separately so that living areas and kitchen areas can be monitored). The electrical input from photo-voltaics will also be measured. In addition to this, the incoming water supply, heat supplied by solar water, thermal performance of insulation materials, external climate monitoring of air temperature and window sensors, will also measure use. Notting Hill Housing Trust is also making available historical bills and asking occupants of its exemplar projects to provide their fuel bills for a period of 2 years to help with monitoring. Surrounding residents will also be asked if they would be willing to have their dwellings monitored and provide information on their fuel bills.


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5. Features of the property after refurbishment

Solar hot water and photo-voltaic panels installed on the flat roof.

New high-performance windows and monitoring equipment was fitted throughout.

Pre-refurbishment

Post-refurbishment

SAP 13 90 EPC Band G Band B Annual running costs

£2020 £220

Annual CO2 emissions

12.3 tonnes 1.95 tonnes

EcoHomes XB

7 91

New A-rated mains gas boiler (and ‘tadpole’ visible in the top left of the boiler) were fitted and linked to a new thermal store.

After internal insulation was applied and decoration undertaken new fixtures and fittings were provided in the downstairs shower room, kitchen and main bathroom.


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6. Funding and construction costs The London Development Agency (LDA) provided a split funding stream to Notting Hill Housing Trust and Hammersmith and Fulham for works relating directly to sustainable measures, over and above the Decent Homes standard. All parties involved in this research/development initiative have invested their time at cost and operated a fully open book approach to the costs. This includes fully engaging with the supply chain. The table below shows the cost breakdown of the eco-refurbishment items and the extra-over cost compared to a typical Decent Homes refurbishment.

Item Total Cost Extra-over cost Ground floor insulation £3,947 £3,947 Comment: 220mm lightweight expanded clay aggregate with 55mm screed External wall insulation £3,192 £300 Comment: extra marginal cost covers the improvement beyond Decent Homes requirements of 0.35 W/m2K to 0.32 W/m2K. Roof insulation N/A N/A Comment: no measures undertake (roof was replaced recently and insulated to 0.15 W/m2K). Windows £22,344 £22,344 Comment: The windows did not need to be changed to meet the decent homes standard; however this exemplar project incorporates timber sliding sash double glazed windows (1.2 W/m2K). Entrance doors £3,378 £3,378 Comment: new solid wood doors where specified. Air Leakage £854 £854 Comment: chimneys where permanently sealed and general airtightness works undertaken. Heating and hot water system £3,573 £0 Comment: A-rated boiler and associated controls installed as standard as a part of Decent Homes works (extra marginal cost of the twin coil thermal store is included with the solar thermal panel cost). Low Energy Lighting £517 £517 Comment: existing lighting circuit did not need replacing, but dedicated low energy light fittings were provided. Smart voltage management system

£360 £10

Comment: was supplied from the manufacturer at near cost to allow evaluation. Photovoltaic panels £10,420 £10,420 Comment: 0.875 kWp photovoltaic array Solar thermal panels £8,420 £8,420 Comment: 2x2.32m2 flat plate solar hot water collectors Rain water recycling £896 £896

Final cost for all works £57,901 Total extra over cost

(beyond Decent Homes requirements) £51,086


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7. Closing comments This project has raised the profile of Notting Hill Housing Trust, Baily Garner and United House and has helped position them inline with future mandatory requirements for the treatment of existing housing stock. Notting Hill Housing Trust have a significant portfolio of Victorian, Edwardian and Georgian housing stock and the next phase includes the exemplar eco-refurbishment of 14 flats using the methods, materials and lessons learnt from 19 Sterndale Road. A proportion of the flats will be improved whilst the residents are in-situ, providing further feedback on how to best deliver eco-refurbishments. A proportion of the future exemplar flats will also be void units, to establish the most cost effective measures which can be incorporated whilst minimising delay in void turnaround times. The Energy Saving Trust would like to thank Notting Hill Housing Trust, Baily Garner and United House in the production of this publication and images used herein.

Energy Saving Trust, 21 Dartmouth Street, London SW1H 9BP Tel 0207 222 0101

energysavingtrust.org.uk/housing

CE334 © Energy Saving Trust March 2011. E&OEThe Energy Saving Trust Housing programme is grant aided by the Department of Energy and Climate Change.

This publication (including any drawings forming part of it) is intended for general guidance only and not as a substitute for the application of professional expertise. Any figures used are indicativeonly. The Energy Saving Trust gives no guarantee as to reduction of carbon emissions, energy savings or otherwise. Anyone using this publication (including any drawings forming part of it) must

make their own assessment of the suitability of its content (whether for their own purposes or those of any client or customer), and the Energy Saving Trust cannot accept responsibility for any loss,damage or other liability resulting from such use.

So far as the Energy Saving Trust is aware, the information presented in this publication was correct and current at the time of the last revision. To ensure you have the most up to date version,please visit our website: www.energysavingtrust.org.uk/housing The contents of this publication may be superseded by statutory requirements or technical advances which arise after the date of

publication. It is your responsibility to check latest developments.

Further informationThe Energy Saving Trust works with the housing industry to providetechnical guidance and solutions to help UK housing professionals design, build and refurbish to high levels of energy efficiency in domestic newbuild and renovation.

For more information visit energysavingtrust.org.uk/housing

Further reading To download this, and to browse all available Energy Saving Trustpublications, visit energysavingtrust.org.uk/housing/publications

Sustainable refurbishment: towards an 80% reductionin CO2 emissions (CE309)

House type scenarios (CE330)

Refurbishing high rise dwellings – a strategic guide for localauthority managers (CE187)

Making private rented housing energy efficient – the flagship homecase study (CE192)

Energy efficient historic homes – case studies (CE138)

Post-construction testing – a professionals guide for testing housingfor energy efficiency (CE128)

External insulation systems for walls of dwellings (CE118)

Internal wall insulation in existing housing (CE17)

Insulation materials chart (CE71)

CE334

stearndale road case study 20.06 - 44 consult · the property had single glazing throughout,...

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