Building Efficiency

• What is desirable/possible?

• How do we achieve it?

Ceiling/Roof

• Combination of air sealing and insulation thickness

• Huge range in conventional buildings

Infiltration/Ventilation

• Build tight, ventilate right

• Buildings have ~ factor of 10 variation in their air exchange rates• Reduce ventilation to what is needed for occupants• Use HRV or economizer

• Do energy efficient fans reduce ventilation load?

Implicit space heating

• Internal gains

• More lighting means less heating• But what about cooling?

What about cooling?

• Can we heat efficiently without compromising cooling?

• Overhangs• Spectral selective glazings• Dehumidification• Radiant barriers

• Issue is peak, not absolute amount of cooling

Water heating

• Central problem is first cost• Natural gas water heater (~$500)• Electric water heater (~$100)

• Gas is faster and cheaper• Safety issues?

• Does insulating the tank make a difference?

LightingType Efficacy

(lumens/W)CRI Lifetime

(1000 hours)

Incandescent 8 - 24 100 0.75 - 2

Fluorescent 60-100 55-90 10-20

Mercury 20-60 15-50 24

HPS 140 22-70 16-40

SOX 180 ~0 10-20

Metal Halide ~100 <70 10-20

Other technologies

• Daylighting

• LEDs/OLEDs

• Microwave lights

• Challenge is balancing maintenance, safety comfort, capital cost, first cost, efficiency

Misc. = 87 TWh in 1995 (residential)

http://enduse.lbl.gov/Info/ACEEE-ResMisc.PDF

Do appliances consume energy when they are off?

• Which appliances?

• How much?

Summary

• Energy efficiency in buildings needs to address• Efficiency of equipment• Efficiency of building (envelope)

• But behavior plays a large role• Take back effect• Energy conservation or load shifting?• Worker productivity/health costs dwarf savings by

technology improvements• Over-optimistic predictions

So what?

• Efficiency is a good thing• Not without consequences

• Need to think about comfort, health, productivity

• How do we achieve it• Laws (energy codes)• Voluntary regulation

• What are the barriers to building efficient buildings? (Amory Lovin’s article on web page – please read first 20 pages)

• LEED critique also on web page

Regulating efficiency

• Appliance standards• http://

www.iamu.org/main/energy/applianc/guide.htm

• Energy codes• http://www.sbcc.wa.gov/docs/01WSEC.pdf

• General idea is that society benefits• Lower air pollution• Less distribution issues

Voluntary Regulation

• People want to do the right thing

• Enhance corporate image

• Save operating costs

• Not as clearly demonstrated• More productive employees• Lower health care costs

Energy Codes

Austin energy code

Conventional Energy Code Compliance Checklist

Glazing percent of gross wall area: 15% 18% 20% 25%

Exterior walls R-13 R-13 R-13 R-13

Floors over unconditioned space R-11 R-11 R-11 R-13

Attics and knee walls R-26 R-30 R-30 R-30

Glazing U-factor (max) 0.75 0.65 0.60 0.52

1.Low-e glass with Solar Heat Gain Coefficient (SHGC) of 0.40 or less must be installed on the windows; 2.Primary water heater and furnace equipment must not be an electric-resistant heating system and meet NAECA standards; 3.Duct connections must be properly sealed with mastic or approved UL-181A/B tape; and 4.Caulking and weather-stripping must be properly installed

Regulated efficiency

• Builders typically don’t like additional codes

• Save dramatic amounts of energy

• Improve quality of buildings

• Very cost effective

• Why aren’t building codes more widespread?

Voluntary Regulation

• People want to do the right thing

• Enhance corporate image

• Save operating costs

• Not as clearly demonstrated• More productive employees• Lower health care costs

Example – LEED v2.1

• The LEED (Leadership in Energy and Environmental Design) Green Building Rating System™ is a voluntary, consensus-based national standard for developing high-performance, sustainable buildings.

http://www.usgbc.org/LEED/LEED_main.asp

LEED™ V.2 • Begins to define “green building”

• Tool to introduce, promote and guide an integrated building design process

• LEED will standardize green design in U.S. and institutionalize integrated design practices

• A compendium of green design elements

• Designed to capture environmental, economic, and human health benefits

• Created for and based on the US commercial market

• Self-assessing system for green buildings

LEED™ V.2

LEED Categories

• Sustainable Sites• Water Efficiency• Energy & Atmosphere• Materials & Resources• Indoor Environmental

Quality• Bonus Points

Certification Levels

• LEED Certified 26-32 pts.

• Silver 33-38 pts.

• Gold 39-51 pts.

• Platinum 52+ pts.

Innovation Credits 4 pts.

AccreditedProfessional 1 pt.

TOTAL POINTS 69 pts.

Examples of LEED™ credits

• Energy Efficiency (pg. 33 in PDF)

• CFC reduction (pg. 32 in PDF)

• Do you think a system like LEED™ is a good idea?

• What problems/issues do you foresee?

Challenges

• Multiple incentives in construction

• Greenwashing

• Substantial fraction of building impact comes from operation

Who conducts the orchestra?

Greenwashing

• A building that is less sustainable than it

appears to be.

• “Green” sells

Green design

• REI Flagship Store (Seattle, WA)• Many green design awards

• Energy efficient operation

• Sustainable material use

Greenwashing

• Does not meet state energy codes• 6 - 30 % above lighting code• Mechanical code violations

• Significant design errors

• Conventional materials for major construction components

• Overbuilt

Further questions

• How does LEED prevent greenwashing? • Can greenwashing be prevented?

• Do voluntary rating systems work?

Operation

• LEED doesn’t address operation and

maintenance issues:

• Scarcity of measured data

• Commissioning

• Pilot standards currently being developed

Predictions

• Energy and water use projections are often

significantly biased

• We overpredict savings/peak reduction

• LEED™ does not verify energy savings

• Take back effect

• Law of unintended consequences

Additional LEED Concerns

• Value engineering of LEED points

• Trading off between quantities that can’t be compared

• Who is at the table?