Superinsulated basement
GBA Editor
| Posted in Green Building Techniques on
I am designing a superinsulated house and I am wondering what the disadvantages would be of saving money by leaving the basement uninsulated or minimally insulated and superinsulating the basement ceiling. I would keep all heating and hot water mechanicals upstairs. I feel I need a full basement since houses built on slabs or crawl spaces are considered low end in my area.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
The basement should be part of the insulated building envelope, pay special attention to water/moisture management. If possible, some daylighting of the basement with windows will help with natural ventilation and make the lower level suitable for living space. Consider egress size windows for future bedrooms.
Will,
Your suggestion can work, but in most cases, including the basement within the thermal envelope is a better strategy.
In very cold climates, basements without any heating equipment (furnace, boiler, or water heater) can freeze, especially if careful attention to air sealing is neglected. Of course, that means frozen pipes. Basements without heating equipment in northern Vermont freeze all the time.
Unlike Doug, I see no advantage to including basement windows unless you have specific plans to use the basement for living space. Ventilating a basement is usually a bad idea, and windows are hard to air seal and insulate.
If you really want to save money, and you have room upstairs for all the mechanicals, then ignore what they neighbors think and build on a shallow-frost-protected foundation. If you don't need the basement space, then you're foolish to waste the money on building one.
I've been building superinsulated homes on such foundations (or rubble trench) for decades.
I was thinking more in terms of a walkout basement with a south exposure or at least 4 or so feet above grade for the southern elevation. Her in MN, we use the basement as living space so we try to make them as comfortable as possible and natural light goes a long way towards livability.