Concept

I have extended the concept of putting active rooms on the south to identifying and grouping core functions, excluding sleeping, where the bulk of these activities can take place in an Active Area. This area is thermally insulated from the rest of the house and it is given heating priority. Furthermore, an Active Area uses and benefits from active solar heating techniques versus typically just passive solar heating.

Application

In our situation, we find that cooking, eating, reading, computer access, TV, homework, laundry, games and most hobby activities can all take place in this core Active Area. That is, over 85% of our daily activities take place in these 720 square feet, which is about 35% of the overall space, and what’s more we could sleep in this area in a pinch and be quite comfortable. It is not exactly the 80/20 rule, but it is close.

One of our highest priorities is to keep the Active Area “comfortable.” For us this means between 68 and 74 degrees year round – without using any fossil fuels. The rest of the house can and will incur larger temperature swings, but this is OK with us.

So, first we maximize our conservation of heat by insulating the ceiling (kids bedrooms upstairs) and back wall (our bedroom suite). This additional insulation pretty much eliminates heat movement to those areas, plus it is great at cutting down sound transmission as well.

Giving this area priority heating happens on three levels:

First, passive solar: We have the bulk of our south facing windows in this area – a total of 101 square feet of glazing for about 720 square feet of floor space. This is more glazing than is typically recommended for passive solar heating; however, the rest of the house is under glazed for passive heating.

The whole first floor is a 3 ½” concrete slab. This slab is just for thermal mass. When the sun shines on the floor, a lot of the heat is captured in this mass and will release later after the sun goes down.

Second, radiant heat: If there wasn’t sufficient sun in a given day, we can run warm water through PEX tubing in the floor in the evening. It is important to run this for just a few hours, so solar collection will not be impaired the next day. If we need a little heat in the morning, we can run the warm water in just the kitchen area. This area gets sun the least and latest, so our heat capturing is not jeopardized.

Third, wood stove: We have a small (42,000 BTU maximum) Jotul woodstove in the center of the back wall. When we need a little additional heat in this area and we are low on heat in the basement storage tank, we can supply it with carbon neutral wood.

When we want to be a little bit warmer, rather than heating the whole house, we can just heat the Active Area, which is a relatively small area. In this way, we maximize our comfort and minimize the heat needed to achieve it.

There will be days when the Active Area over heats, whether by the sun or wood stove (intentionally or accidentally). When that happens we can both cool it and send the heat to other areas of the house – see Heat Management System.

It is important to keep in mind that most of the year, the whole house will be quite comfort and activities can occur where ever desired. On many days the Active area will be heated solely by passive solar means and the other rooms will be just a bit cool. On those days we will gravitate to the Active Area for whatever we are doing; this is part of the necessary mind set change – adjusting what we do and where we do it, to live within our resources – rather than just flip a switch to burn fossil fuel and pollute the air.

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