Morofsky1 Low-energy Building Design, Economics and the Role of Energy Storage Canadian possibilities based on the Model National Energy Code for Buildings.

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Low-energy Building Design, Economics and

the Role of Energy Storage

Canadian possibilities based on the Model National Energy Code for

Buildings

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Model National Energy Code for Buildings (MNECB) 1997

• The MNECB is a model code that can be adopted (or adapted) by any province or territory in Canada.

• The MNECB references Canadian standards and regulations and uses metric (SI) units.

• Cost-effectiveness of the provisions was guiding principle of the MNECB.

• Country was divided into 34 administrative regions because of variation of construction and energy costs and climate. Life-cycle cost process applied in each region.

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Model National Energy Code for Buildings (MNECB) 1997

• Provisions of MNECB are more stringent in colder regions and for buildings heated by more expensive fuels.

• Two paths to compliance - prescriptive and performance.

• Prescriptive - meet all mandatory and prescriptive requirements - easiest path to follow for compliance.

• Performance - involves detailed computer simulation - most flexible, but most complex path. Building does not have to meet some prescriptive requirements of Code but must not use more energy than prescriptive path.

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Measure Description

En

ergy S

avings

Pay-

back

S0 Base case 0.0 S1 Lighting power density of 11.5 W/m2 3.7 2.5 S2 Perimeter daylighting with light dimming 2.5 2.8 S3 Occupancy sensors for lighting 3.1 5 S4 Active solar shading 1.1 137 S5 Add low-emissivity coating to windows 8.0 7.7 S6 Add low-emissivity coating and argon fill to windows 9.3 9.3 S7 Add low-emissivity coating, argon fill, and vinyl framed windows 13.2 8.5 S8 Triple-glazed low-e coated, argon filled, vinyl framed windows 21.0 10.4 S9 Increase wall insulation by ΔRSI = 0.9 3.2 6.1 S10 Condensing boiler (thermal efficiency = 95%) 13.0 5.6 S11 Central air-to air heat recovery 60% annual effectiveness 4.9 6.3 S12 Solar air preheating system 2.8 28.6 S13 Install high efficiency motors on supply fans 0.1 8.2 S14 Variable speed pump on heating loop 0.0 never S15 WLHP system with condensing boiler and cooling tower 16.4 0 S16 WLHP system (same as S15) plus thermal storage 16.7 0 S17 WLHP system with ground source 34.0 14.2 S18 Radiant panel heating and cooling with displacement ventilation 18.6 0 S19 Low flow faucets 0.8 0 S20 Heat pump water heaters 2.1 8 S21 Solar thermal domestic hot water system 2.0 24.6 S22 Photovoltaic electric array 2.2 244 S23 Microturbine with heat recovery - ? S24 Low-energy office equipment 1.8 0 S25 Elevator efficiency measures 1.6 0 S26 Increase roof insulation by ΔRSI = 0.9 1.0 10.9

Individual measures with energy and cost comparisons to the base case.

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Measure set definitions: SA, . . . , SM

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Introduction

• Investigate the potential energy efficiency of office buildings from the appropriate application of available technologies.

• Objective - dramatically reduce whole building energy compared to a building constructed to Canada’s Model National Energy Code for Buildings 1997 (MNECB).

• Results of modeling efforts to-date on a small office building and how energy efficiency technologies can minimize energy use in office buildings in Canada.

• Heating and cooling load requirements for low energy office buildings in Canada and implications for energy storage.

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3.1

Each new or rejuvenated building be at least 35 % more energy efficient than that which it replaced and/or at least of 25 % less than the Model National Energy Code for Buildings (1997) (MNECB-1997) by April 2004

3.2

By March 2006, an assessment be conducted for new building construction projects to identify feasibility to achieving an increased reduction to 40 % less than MNECB-1997;

Two sustainable development departmental objectives

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0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

GJ

S0* SA SB SC SD SE SF SG SH SI SJ SK SL SM

Figure 1. Energy Usage versus Measure Sets for a Small Office Building in Ottawa, Canada.

Elevators

Pumps

Fans

Equipment

Interior Lighting

Domestic Hot Water

Space Cooling

Space Heating

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Table 2. Space heating and cooling versus measure sets for Ottawa.

 Measure Sets

S0 SA SB SC SD SE SFSG

SH

SI SJSK

SLSM

Space Heating MJ1,613

935

791

503

227

1,392

922

541

1,055

623

318

344

230

148

Reduction Heating % -42%

51%

69%

86%

14%

43%

66%

35%

61%

80%

79%

86%

91%

Space Cooling MJ235

192

190

244

152

162

149

168

199

208

240

125

131

140

Reduction Cooling % -18%

19%

-4%

35%

31%

37%

28%

15%

12%

-2%

47%

44%

41%

Table 2. Space heating and cooling versus measure sets for Ottawa.

  Measure Sets

S0 SA SB SC SD SE SF SG SH SI SJ SK SL SM

Space Heating MJ 1,613 935 791 503 227 1,392 922 541 1,055 623 318 344 230 148

Reduction Heating % - 42% 51% 69% 86% 14% 43% 66% 35% 61% 80% 79% 86% 91%

Space Cooling MJ 235 192 190 244 152 162 149 168 199 208 240 125 131 140

Reduction Cooling % - 18% 19% -4% 35% 31% 37% 28% 15% 12% -2% 47% 44% 41%

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Energy Criteria - Low-rise Office (MNECB) - Ottawa

(4200 m2)

Infiltration - 0.25 l/s/m2 exterior wall

Outdoor air - 0.4 l/s/m2 floor area

HVAC system - Individual zone packaged rooftop

- DX air cooled (EER-8.9) with economizer

- Gas-fired central boiler

SHW system - Peak demand 90 W per person

- Electric storage heaters

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Energy Use - Low-rise Office (MNECB) - Ottawa(4200 m2)

End Use kWh GJ % Total

Heating 36,844 3,099 61.2Cooling 66,435 - 4.5SHW 53,288 - 3.6Lights 217,863 - 14.9Equip/Appliances 117,037 -

8.0Fans 63,372 - 4.3Pumps 8,297 - 0.6Elevators 41,808 - 2.9Total 604,944 3,099 100%Total (ekWh) 1,465,935 100%Building Peak 303 kW 1,260 MJ / m2

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Example Path to Low Energy Use

End Use Measures

Heating/Cooling - increase wall insulation (RSI 0.9)

- use argon, low-e, vinyl frame windows (U overall = 1.86)

- ground-source heat pump system

(EER-15.5, COP-3.4)

SHW - low-flow faucets in washrooms

(6.8 lpm)

Lights - reduce lighting to 10.8 W/m2

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Energy Use - Low-rise Office Example Low Energy

End Use kWh GJ % Total % ChangeHeating 102,392 16.1 -88Cooling 40,017 6.3 -40SHW 42,460 6.7 -20Lights 132,030 20.7 -39Equipment / Appliances 117,037 18.4 -Fans 110,691 17.4 +75Pumps 50,643 7.9 +510Elevators 41,808 6.5 - Total 637,078 100%Total (ekWh) 637,078 100% - 56.5 %

Building Peak 205 kW 546 MJ / m2

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Result of Applications of Measures

• The heating and cooling energy use has been reduced by 85% as a result of load reduction due to improved envelope and the efficiency of the heat pump.

• The service water heating energy use has been reduced by 20% as a result of the load reduction (less hot water use).

• Lighting energy use is down by 39% as a result of the lighting density change.

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Result of Applications of Measures (cont’d)

• Fan and pump energy use is up significantly with the ground-source heat pump system.

• Net result - 56.5% saving relative to the MNECB base case.

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GSHP Requirements

Land requirement for a 100-meter vertical system is about 550 m2 less than the 32-meter square foot print if the building has four storeys. A typical cost might be $130,000. Note that the energy extracted and added to the ground exchanger is similar at 284

MWh heating and 202 MWh cooling.

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Further Steps to Lower Energy Use

Heat / Cool - solar shading

- displacement ventilation with HR

- solar wall (ventilation pre-heat)

- demand ventilation (CO2 control)

SHW - solar thermal heating

Lighting - perimeter daylighting with

automatic dimming

- occupancy sensors

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Further Steps to Lower Energy Use

Equipment /Appliances - office equipment-low idle power use / smart controls

Fans / Pumps - energy efficient fans / pumps / motors

- variable speed pumps

Elevators - efficiency measures for elevators

Power - microturbine with heat recovery

- photovoltaics

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GSHP Conclusions

• Office building energy use can be significantly reduced in new building design compared to the MNECB. The example presented was 56%.

• More opportunities exist to reduce heating load (heat recovery), further improve lighting and incorporate on-site power production /cogeneration.

• Ground-source heat pump system heat exchanger layout fits within footprint of building.

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Energy savings over 50% were achieved in five measure sets (SG, SJ, SK, SL, SM) and four had discounted payback periods between 2.5 and 6 years.  25% reductions compared to the base case building with no incremental cost (SE, SF, SH, SI). Designs can result in energy savings of 30 to 40% with no incremental cost. The integrated design process process has been successfully applied where the energy reductions have confirmed simulation results. Existing buildings represent a much larger opportunity than new buildings. Many measures would be applicable when major system upgrades, replacements or building retrofits are undertaken. Even pre-mature retrofits could be justified on a life cycle cost basis.

General Conclusions