nbec 2014 - high performance retrofits
TRANSCRIPT
Evaluating the Energy Savings of High Performance Building Enclosure Retrofits
GRAHAM FINCH, MASC, P.ENG, PRINCIPAL,
RDH BUILDING ENGINEERING LTD. VANCOUVER, BC
COAUTHOR: BRITTANY HANAM
Outline
à Background – Energy
Use in Multi-Unit
Residential Buildings
à Deep Energy Retrofit
Case Study
à Measurement &
Verification of Energy
Savings
à Other Monitoring
Results
NBEC 2011: MURB Energy Study
à Study looked at energy consumption of
over 60 MURBs in Pacific Northwest
à Constructed from 1974 -2002
à 5 to 35 storeys in height
à Half of study buildings underwent a full
building enclosure rehabilitation
à Assessed actual performance
characteristics in each building
à Decade of energy consumption
à Effective R-values
(design vs. in-situ)
à Airtightness of enclosure & interiors
à Impact of building enclosure repairs
and upgrades
Energy Use Intensity of Mid- To High-Rise MURBs
Average 39 Buildings = 213 kWh/m2/yr (68 kBtu/sf/yr)
Typical Mid- to High-Rise MURB Energy Consumption
Units of kWh/m2/yr, % of total
Energy Savings from Building Enclosure Rehabilitations
à Enclosure rehabilitations performed at
study MURBs primarily to address moisture
damage
à Little incentive for owners to perform energy
upgrades due to increased cost – a huge
missed opportunity
à Full re-cladding, over-insulation and new
windows at each building
à Thermal improvements from: exterior
insulation assemblies, improved detailing
(i.e. cladding attachments), better windows
(thermally broken, low-e, argon etc.)
à Improved air-tightness characteristics during
rehabilitation
Typical Rehabilitation – Typical Detailing
Pre-Rehabilitation
Post-Rehabilitation
Measured Savings from Building Enclosure Rehabilitations
Average 14% Space-Heat Energy Savings & 8% Total Building Energy Savings
Make-up air unit not running prior to rehab (savings negated)
Energy Retrofit Potential for Existing MURBs
à Study identified several key components to be improved during enclosure rehabilitation work or as part of specific energy retrofits
à Study found potential for building enclosure retrofits (windows, wall insulation, air-sealing) to reduce space-heat use by up to 90%!
à Further savings from ventilation upgrades (heat recovery, in-suite systems) & other building system improvements (fireplaces, DHW, lighting etc.)
à 13 storey, 37 suite, multi-unit
residential building
à Constructed in mid 1980s
à Building renewals pursued at
decision of owners to upgrade
original building enclosure
à Aesthetics
à Poor thermal performance/
comfort
à Concrete/PT cable repairs
needed
Case Study Renewal Project: Background
Existing Building Enclosure Assessment
à Representative of typical
1970s to 80s vintage mid- to
high-rise MURBs
à Exposed concrete walls (R-4),
non-thermally broken
aluminum frame double
glazed windows (R-1.8)
à High window to wall ratio,
55% - similar to many
modern buildings
à Overall Effective Enclosure
R-value = 2.8 IP Fig. 1.1 Original detail drawing of a window head and sill, coloured.
Existing Mechanical System Assessment
à Original mechanical systems
largely in place
à Electric baseboard heating
à Gas-heated make-up air for
ventilation, <80% efficient
(to corridors)
à 14 decorative gas fireplaces at
upper floor suites – few
replaced by owners
à Hot-water boiler & tanks
replaced few times before
Metered Energy Data
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
Jul 200
6Sep 20
06Nov 200
6Jan 20
07Mar 200
7May 200
7Jul 200
7Sep 20
07Nov 200
7Jan 20
08Mar 200
8May 2008
Jul 200
8Sep 20
08Nov 200
8Jan 20
09Mar 200
9May 200
9Jul 200
9Sep 20
09Nov 200
9Jan 20
10Mar 201
0May 201
0Jul 201
0Sep 20
10Nov 201
0Jan 20
11Mar 201
1May 201
1Jul 201
1
Mon
thly Ene
rgy Co
nsum
ptoin, ekW
h
Suite Electricity, kWh
Common Electricity (Strata), kWh
Gas, ekWh
Typical Year Energy Consumption
à Calendarize and weather normalize
-‐
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
Mon
thly Ene
rgy Co
nsum
ption, ekW
h Suite Electricity, kWh Common Electricity, kWh Gas, ekWh
Gas46%
Suite Electricity36%
Common Electricity (Strata)18%
Annual Breakdown
Energy Modeling to Evaluate Energy Efficiency Measures
à Reviewed measured utility data (gas and electricity) for past 5 years
à Calibrated whole building energy model developed to evaluate potential
Energy Efficiency Measures (EEMs)
Electric Baseboard Heating22%
Fireplaces9%
Ventilation Heating25%
Hot Water11%
Lights -‐ Common2%
Lights -‐ Suite7%
Plug and Appliances (Suites)8%
Equipment and Ammenity (Common)
16%
Total Energy
Consumption =
225 kWh/m2/yr
Average in MURB Study
was 213 kWh/m2/yr
Energy costs $65,500/yr
total ($1770/suite)
à Plan to renew building
aesthetic to more modern
appearance à Metal panels with color
features
à Stucco features
à New windows
à New skylights at penthouse
à New entrance door
à Enclosed balconies
à New roof and decks
à Adds value
Building Enclosure Renewal Design
à Exterior wall insulation with low
conductivity cladding attachment
& high effective R-value
à Windows Upgrades à Double & triple glazed low-
conductivity frames (R-4 to R-6)
à Airtightness improvements
à Roof insulation
à Fireplace upgrade
à Make-up air unit (ventilation)
à Heat recovery ventilation
Potential Energy Efficiency Measures (EEMs)
Cost Payback Analysis – Building Enclosure & Mechanical EEMs
Energy Efficiency Measure /
Incremental Upgrade
% Total Energy Savings
(% Electrical Heat Savings)
$ Savings per year
Incremental Cost with
Utility Incentives
Simple Payback
Wall Insulation & Improv. Cladding Attachment 4% (19%) $4,800 $0 Immediate
Double Glazed Fibreglass Windows 7% (30%) $7,600 $2,700 0.4 years
Triple Glazed Fibreglass Windows R-5 10% (44%) $11,000 $60,000 6 years
Airtightness 2% (7%) $1,800 $0 Immediate
Fireplace Replacement 2% (8%) $2,100 $14,000 7 years
In-Suite HRV Installation 6% (-32%) -$4,400 $74,000 n/a
Make-up Air Unit Replacement 5% (0%) $1,600 $23,500 15 years
Enclosure EEMs (triple glazed) 20% (87%) $21,900 $60,000 2.7 years
Enclosure & Mechanical EEMs (triple glazed) 30% (62%) $19,700 $166,800 8.5 years
Predicted Annual Energy Savings
Electric Baseboard Heating3% Fireplaces
9%
Ventilation Heating24%
Fans1%
Hot Water11%Lights -‐ Common
1%Lights -‐ Suite
7%
Plug and Appliances (Suites)8%
Equipment and Ammenity (Common)
15%
Enclosure Savings21%
Modeled Post-Retrofit: 177 kWh/m2
à Pre-retrofit = 225 kWh/m2/yr
à Building enclosure EEMs (insulation, windows, airtightness) à 20% savings overall
à 87% electric baseboard
heating savings
Building Enclosure Renewals
à $3.6M renewals project,
7-month construction period
à Work primarily from exterior
with access to suites for
window installations
Building Enclosure Renewals Performed
à Over clad and exterior insulate walls
with mineral wool & fiberglass clip
cladding attachment (R-16 effective)
à New triple glazed fiberglass windows
(R-5 effective)
à New roof and decks
à Improved air-tightness
à Measured Pre-Post reduction of
0.71 to 0.32 cfm/ft2 @75Pa
(55% Improvement)
à Overall new enclosure R-value
R-9.1 vs R-2.8 original
Existing
Upgraded
Exterior Insulation, Stucco, & Metal Panel Overcladding
New High Performance Triple Glazed Windows
Completed Building Enclosure Renewals
Measured Energy Savings & Other Research
à Measurement & Verification Plan (IPMVP)
à Energy savings metering primarily through utility
meters (smart meters & sub-meters)
à Supplemental sensors installed to measure
indoor conditions (T/RH/CO2), airflows,
pressures, occupant comfort, fireplace use
à Air-tightness testing (Pre-Post Renewals)
à Tracer Gas Testing (Post Renewals
à See Other NBEC Paper (Lorne Ricketts)
Metered Savings: Suite Electricity
à Total Electricity Reduction of 33%
à 63% Reduction in Electric Baseboard Heating
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10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Ele
ctri
city
Con
sum
pti
on
, kW
h Calibrated Model Pre-Retrofit Calibrated Model Post-Retrofit
Metered Savings: Natural Gas
à 2% Reduction in Gas (Fireplaces)
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10,000
20,000
30,000
40,000
50,000
60,000
70,000
Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
Gas
Con
sum
pti
on
, ekW
h
Calibrated Model Pre-Retrofit Calibrated Model Post-Retrofit
Metered & Modeled Energy Savings: Year 1
à Overall Energy Use Intensity (EUI) reduced from
226 to 183 kWh/m2/yr
à Overall 19% Reduction in Energy Consumption
à Predicted ~20% prior to retrofit
à Energy models can be accurate predictors of actual energy
use, but only with good calibration
à Pilot Study demonstrates building enclosure renewals can
predictable & successful in reducing energy consumption
à Further savings possible (many windows left open year
round)
à Plan to upgrade mechanical
ventilation system (old
central pressurized
corridor)
à Most effective retrofit is to
install continuous
ventilation to each suite &
utilize insuite HRV/ERVs
à Compartmentalization of
suites and corridors
à Measure ongoing energy
savings
Next Steps
Summary
à Significant opportunities exist to reduce energy consumption of MURBs
à Pilot project demonstrates the potential for cost effective incremental EEMs at time of retrofit work & new construction
à Total building energy savings of ~20% for building enclosure improvements predicted and demonstrated
à Ventilation assessment at time of building enclosure renewals
à Replicating the success of this project is a huge opportunity for the entire retrofit industry
Acknowledgements
à RDH – Brittany Hanam, Lorne Ricketts, Robin Urquhart, James Higgins
à Homeowner Protection Office, Branch of BC Housing
à BC Hydro
à FortisBC
à National Resources Canada
à Enbridge Gas
à City of Vancouver
à City of North Vancouver
à City of Surrey
à City of New Westminster
à City of Richmond
