Real Performance of Green Buildings:

The Role of Delivered Performance to Achieve Real Savings

Stephen CarpenterEnermodal EngineeringJune 3, 2009

Creating energy and resource efficient buildings

Background

USGBC presented results that US LEED projects saved ~25% energy compared to standard buildingsLstibrek said “LEED plaques should come with screws until performance is proven” “Gifford makes the controversial case that LEED certified buildings use more energy than comparables, not less- as much as 29% more.”

Creating energy and resource efficient buildings

Background

What are results for Canada?

Enermodal is leading green consultant in Canada with 43 LEED certified projects 45% of all LEED Canada NC certified buildings Results for 6 LEED buildings presentedShow how Delivered Performance helps buildings achieve their potential

Creating energy and resource efficient buildings

How Do We Determine if Green Buildings Really Work?

Very little data on real performance of green buildingsSome well known green buildings have not shown significant savings over other new buildingsMost claims are based on design phase computer simulationsSimulations must be calibrated to real operation, weather etc. Better to compare utility bills to utility bills

Creating energy and resource efficient buildings

How Do Conventional and Green Buildings Perform?

Creating energy and resource efficient buildings

Energy Use of All Buildings – By Age of Construction

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Before 1920 1920 - 1959 1960s 1970s 1980s 1990s

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Survey of Energy Use in Canadian Buildings 2000

100 93

Ref: Commercial and Institutional Building Energy Use, NRCAN 2002Sample size: 137,039 buildings, 302,570,981 sq m

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Monitored Performance of 6 LEED Projects

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Water Savings: A Tale of Two Fire Stations

Station 79 was intended to be duplicate of 7879 was greened up but floor plan unaltered

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Water Use at Two Identical Fire Stations

68% annual water savings

Creating energy and resource efficient buildings

Are Green Buildings Performing Up to Expectations?

The Role of Delivered Performance

Creating energy and resource efficient buildings

What is Delivered Performance?

Comprehensive post-construction consulting service that delivers better performing buildings Single packaged service that includes: – Fundamental Commissioning– Best Practice Commissioning– M & V– Building airtightness review and testing– Building IAQ Testing– Green Education and Promotion (optional)The whole is more than the sum of the parts

Creating energy and resource efficient buildings

What is Delivered Performance?

A mindset where we are designing buildings to achieve real savings not predicted savingsDon’t do things that don’t save energy – occupancy sensors in hospital corridorsDo do things that save energy even if no sim credit– instantaneous heaters and avoid hot water recirc systemOur role is to work with the owner to get the building to perform as close as possible to its potential and identify action the owner could take to further improve operation

Creating energy and resource efficient buildings

Delivered Performance in Practice

LEED-NC currently assesses building energy performance based on simulated performance

But energy simulations are really just an indication of the potential for a design to be efficient… relative to a particular reference case… and under a specific set assumptions

Need to “calibrate” the energy simulation

Creating energy and resource efficient buildings

Calibrated Energy Consumption

Most simulations do not account for all energy uses in a building – sometimes “ignored” energy in LEED compliance simulations can be very significant:

– Exterior lighting, Kitchens, Servers, Elevators, Humidification

Energy uses can be highly dependent on occupant behaviour and hard to predict

Creating energy and resource efficient buildings 15

4.8 L/100 km 11.5 L/100km

Occupants Affects on Energy Consumption

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Calibrated Energy Consumption

Example Building Calibration Process:1. Weather2. Exterior lights3. Ground loop temperature revision4. Kitchen electricity5. Kitchen process loads6. Humidification7. Kitchen gas use8. Heat pump spec update9. Elevator electricity10. Ground loop pump update11. Ground temperature updates

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Calibration Iteration

Preliminary Model Measured Performance

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Process 51

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Importance of Energy Monitoring

Initial monitored results were 15% above predictedCommissioning with M&V reduced to 2% below predicted

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Dec. 2007 - Feb. 2008 March - May 2008 June - August 2008 Sep. - Nov. 2008

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Annual Energy Performance

Baseline Actual Potential

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Case Study: TRCA Restoration Services

Design Phase Simulation Results

LEED Status: Platinum LEED Energy Savings: 65% (10 pts)

AnnualEnergy

ekWh/m2

Creating energy and resource efficient buildings

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Feb '05 (SL) Mar '05 (SL) Aug '06 (CBIP) Feb '07 (Review) May '07 to Apr '08

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Actual

Case Study: TRCA Restoration Services

Actual Performance

AnnualEnergy

ekWh/m2

Is this just luck?

Creating energy and resource efficient buildings

Case Study: TRCA

Changes to “calibrate” energy simulation:Update with weather informationAdd in “kitchen processes” (including cooking appliances and make-up air/exhaust system)Add in energy use related to the snow melt systemUpdate affecting ground loop pump energy calculation

Creating energy and resource efficient buildings

Case Study: Natural Gas

Contractor had crossed floor loops: office t’statcontrolling floor heat in storage room. Investigations revealed user issues: garage doors being left open, unit heater operation, t-stat settings.

Creating energy and resource efficient buildings

Case Study: Electricity

1 meter not working, filled in the gaps with manual readings from clientFaulty heat pump: supplier blamed system, contractor blamed supplier (but no one measured any parameters)

Creating energy and resource efficient buildings

Case Study: Water

Rain water cistern, low-flow fixtures, composting toilets.Showers not being used as frequently as anticipated?

Creating energy and resource efficient buildings

Comparison of Actual to Predicted Water Use

Creating energy and resource efficient buildings

Conclusions

Initial data indicates LEED buildings appear to offer significant energy and water savings

Actual Energy use ~ 200 kWh/m2

M&V critical to diagnose problems and improve operation over time.

Calibrated simulation can accurately potential building performance

Poor agreement between predicted and actual water use

Creating energy and resource efficient buildings

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