Conditioned Space Attic

Making the attic a conditioned space taking the building envelope to the roof is a good approach and will save energy another approach is to use radiant coated deck sheathing seal all ceiling attic penetrations and blow in r 60 insulation as it will cost less than spray foam and should give at least the same energy efficiency to the home.

Conditioned space attic.

The air handling unit is located in a conditioned basement. Unvented conditioned attics were quite rare before the 1980s. Lstiburek s enthusiasm was rooted in his desire to bring attic ductwork inside a home s thermal envelope. So why put an hvac system up in the attic at all.

The acceptance of unvented conditioned attics continues to grow among builders and building officials. Most updated central air conditioned homes have a new air conditioner split system meaning the ac is broken up into parts. The irc has permitted unvented conditioned attics since 2006 with certain requirements. In unfinished attic spaces insulate between and over the floor joists to seal off living spaces below.

The roof deck in an unvented attic must be exceptionally airtight. Well mainly it s a way to save space. Heat pumps heat pump water heaters or sealed combustion furnaces and water heaters should be used. 1a attic access door.

If the air distribution is in the attic space then consider insulating the rafters to move the distribution into the conditioned space. Attic hvac systems save space. Low efficiency gas appliances that are prone to spillage or backdrafting are not recommended in this type of application. The attic space becomes indirectly conditioned as a result of the air leakage heat transfer and vapor diffusion through the ceiling.

Code requirements vary across the country. Ducts in conditioned space details figure 1 vented and unconditioned attic. A fundamental requirement of an unvented attic assembly is the use of air impermeable insulation on the underside of the unvented roof to prevent air infiltration and exclude airborne moisture from the attic. Most contractors would never consider installing uninsulated ducts in a vented attic or crawlspace but regularly do in basements and foamed attics.

Is the attic used for a significant amount of storage. A common idea promoted across the industry is that any heat lost from an uninsulated duct system to a conditioned space isn t truly lost and has no effect on energy consumption.