HVAC in one builder's SIP homes
Since 1986, Controlled Environment Structures (CES), a SIP builder and distributor in Greenville (Michigan), estimates they've installed over 500 structures and roof projects using R-Control panels from Team Industries. After years of seeing how energy efficient their early structures were, CES co-owner Joe Ellsworth realized most home heating requirements were low enough that they could be met by a water heater. For this to be possible every time, CES insists that each new shell be well insulated. The key features are R-4 windows (in their case, Eagle vinyl units with low-e and gas filling); use of 6.5-inch SIPs in both the walls and foundation; installation of 8.25" SIPs in the ceilings; and extremely tight construction. CES knew this package wouldn't need much heat.
Typically, heat is supplied by a 50-gallon, 65,000 Btu Bradford White water heater. A pump circulates hot water from the water heater to a water-to-air heat exchanger. Then a blower in the Lifebreath Fresh Air Furnace draws room air through conventional return air ducts plus some fresh air ducted in from the outdoors, blows it past the water-to-air heat exchanger, and distributes the warmed air throughout the home as needed. When heating isn't required, the unit-like any heat recovery ventilator-just brings in "tempered" fresh air.
How well does this generic concept work? Ellsworth reports that one 3,600 ft2 home on an exposed ridge in north-central Michigan costs about $300 to heat for an entire winter. Another 3,000 ft2 home heated for $262 during the coldest winter on record. What particularly pleased one retired couple was how even the temperatures were in their new SIP home; using the low-volume air mixing and heating system meant they measured only a one-degree temperature difference from their floor level to the top of their 22-foot vaulted ceiling.
CES and their dealer network erect pre-cut shells throughout Michigan. Ellsworth says that while sales were slower than expected during the early 1990s, sales have exploded during the past few years. "We've been growing 40% to 50% last year and this year. We're swamped managing that growth. Today the acceptance curve around here is nearly vertical."