November 14th, 2012

Ann Vole

4 building zones

I realized early on that buildings made for my area are not necessarily applicable to other areas but I never really looked at the other areas for what is best for them. This became clear when I was mentioning building designs for Norway, Sweden, and Germany as being the inspiration for my designs. I is also clear when I find myself rejecting most energy efficient designs for other parts of the world. The four zones, requiring unique strategies in design, are as follows:

1) constant heating load... the average temperature over a week remains below room temperature through 90% of the year or more. Thermal mass makes little difference but insulation and air-tightness is king in these areas. Heat Recovery Ventilation is a requirement. Buzz terms include "one watt house" and "passivhaus"

2) large daily temperature swings... generally dry areas. The average temperature stays close to room temperature (or is higher but with dry air) most of the year but the daytime highs and night time lows are extreme. Thermal mass is king in these areas. Most "earth ship" designs are in this area such as the South West parts of the USA. This would also characterize much of the middle east areas and the drier parts of Africa and China.

3) much of the area between #1 and #2 above. The temperature cycles daily most of the year and the average temperature is lower then room temperature for some of the year. For these areas, passive solar design is king. You need good insulation but not too much or you cook in the summer. Thermal mass is only in the sun-drenched part of the house for storing sun-produced heat for the night. Trombe walls work great in these areas (a high mass wall with a window placed a few inches away on the south side of the building... the sun shines in and heats the wall which radiates into the house at night).

4) hot and humid. Places with an average temperature that is hotter then room temperature for most of the year can sometimes use ground cool storage methods such as the Earth Ship designs but those designs do not have a solution for high humidity. To control humidity and to provide cooling, refrigeration in the form of heat pumps is needed. These areas need high insulation, air-tightness, and a heat pump for good comfort levels. The heat pump can be powered with renewable energy and can be used in the day when the sun is shining or the cold can be stored as ice and use cheaper electricity at night. Fresh air is sometimes delivered with a special kind of heat recovery ventilation unit that extracts moisture from the fresh outside air as it cools and adds it to the exiting stale air as it warms to outdoor temperatures.