temperature swings. Metal frames may contain up to 90 percent recycled material, and can be advanta 

geous where moisture, termites, or other natural pests are a problem, or where occupants are particularly

sensitive to chemicals used in other products. 

Energy Consuming Equipment. Energy consuming equipment in homes and small businesses

include systems such as HVAC, water heating, and lighting.

HVAC Systems

Many technical opportunities exist to save energy used in HVAC systems. Smarter control systems

could maximize the use of natural ventilation, especially if used with some form of thermal storage.

Controlling relative humidity in air conditioned spaces within the proper range would permit higher air

temperatures while providing equal occupant comfort.

85

Successful methods are already available to

reduce the large (estimated in the 15 20 percent range) duct energy losses including aeroseal tech 

niques.

86

Variable speed air handlers are also available to improve system efficiency and performance.

87

In the long term, selective water sorbent technology offers the promise of meeting the performance of

ground coupled heat pumps at the cost of traditional systems. Moreover, the sorbent technology inherently

includes a variable temperature energy storage mechanism that can be used to shift electric loads from

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peak to off peak times.

88

Matching HVAC size to the building load has multiple implications for GHG emissions.

Historically, contractors have considered it conservative to oversize HVAC installations, often using  rules

of thumb  unrelated to any particular house design and especially inappropriate for the newer, more

energy efficient houses. Such oversizing causes units to cycle on and off more often, increasing thermal

losses during each on/off transition. Frequent cycling also reduces occupant comfort, which in turn often

leads occupants to adjust their thermostats to a value that increases total energy consumption. Therefore,

downsizing HVAC equipment to match the reduced requirements of an energy efficient building envelope

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can save investment dollars up front and can decrease energy consumption and GHG emissions as well.

Until recently, oil furnace efficiencies above the low  to mid 80s were rare. The availability of high 

efficiency oil furnaces could significantly affect energy use through installation in new homes or as replace 

ment units.

89

One manufacturer has developed a condensing oil furnace with an Annual Fuel Use Efficiency

(AFUE)

90

rating of 95 that has overcome sooting problems prevalent with earlier versions of this technology.

91

30

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Towards a Climate Friendly  

Built Environment