My wife Gwen and I recently had an opportunity to tour a number of Net Zero Energy homes in Alberta. One of the highlights of the trip was a guided tour of three Net Zero homes in Edmonton. Our guide was Gordon Howell of Howell-Mayhew Engineering, Inc. Gordon is an electrical engineer and specializes in solar (photovoltaic) energy. He was a key player in the design of the three homes we visited in Edmonton.

We learned a lot about Net Zero homes and different design strategies. One of the things that really impressed me was the importance of energy efficiency.  The homes that Gordon designed had R56 walls and R100 ceilings. Compare this to the R20 walls and R40 ceilings of typical home construction today. The savings on the home heating bill from this extra insulation are projected to be an amazing 53%.

The most interesting part is how they accomplished this. They use cellulose for insulation. One inch of Cellulose provides the equivalent of about R3.6 of insulation. To achieve R56, the walls need to be 16 inches thick. The designers have developed a unique double wall construction that is a cost effective way to build a 16 in wall.

R100 ceiling

The R100 ceiling requires just over 27 inches of cellulose. This is much easier to accomplish in standard roof construction although special construction is required in the ceiling hatch: