What a church building needs to be is comfortable. No one wants to come into a building that is uncomfortable and sit still for an hour or two in a cold or hot building. Also, it is expensive to heat or cool a building using the modern American energy-squandering methods.
There is another way, and here is how to construct a new building, any building, that is nearly 100% energy neutral, and yet perfectly comfortable year around. This is intended primarily for buildings in Bend, Oregon, which is located at 3600 foot altitude. The building needs some heat nearly every day of the year but cooling only a few days in July and August. When we look at the entire year there is plenty of time when there is abundant heat input from the sun, and alternatively there is plenty of time below freezing to cool the building. The problem becomes how to time shift the movement of heat and cold into the living space at appropriate times. When looked at in the long run — that is, a whole year at a time instead of a day at a time — it becomes a problem of storing heat energy that is available at one time and supplying it at another time. The goal is to make people very comfortable when they enter the building.
People like the indoor temperature to be 72°F plus or minus 2°F at about 50% humidity. That is a generally accepted figure, but what is rarely discussed is the infrared temperature of the surrounding walls, floor and ceiling. If a person is sitting in a 72°F room, near a typical large single pane window when the outdoor temperature is cold, say anything under 40°F, they will feel cold on the side facing the window. This cold feeling becomes very noticeable when the outdoor temperature is under 20°F. An easy experiment to perform on a cold day is to stand near a window in a warm room and about a foot from the window, turn your palm toward the window and away from it at about a five second cycle. It is very easy to feel the cold even though your hand doesn’t change temperature, even a little. The opposite effect can be gotten from a hot brick wall just after sundown when you can feel the radiant heat from the wall.
What needs to be done is to heat the floor and walls to about 72°F so they will radiate infrared heat at that comfortable temperature. Typical heating systems only heat the air, and let the surfaces fend for themselves. That works okay on cold days if there are no external walls facing the people, because the internal walls reach the air temperature and stabilize there, but most rooms have external walls and so those walls are usually well below the room’s air temperature. On cold days the external walls radiate discomfort. Technically your warm body radiates its infrared heat away toward the colder surface. When your body’s comfortable level of radiant heat is identical to the walls’ radiant heat you will be comfortable. But when your radiant heat is much above or below the walls’ radiant heat, you will be uncomfortable.
The problem of how to create comfortable people now becomes how to have the surface temperature of the room at about 72°F, year around. And that becomes how to move the heat of the sun into a large thermally controllable mass for warming the walls and conversely how to move the cold of the freezing cold air of the winter nights into a separate large thermal mass. Once we know the size of the exterior walls of the building and the measured R value of those walls, we can calculate the total thermal units that are needed to keep the interior thermally stable. Once those numbers are known, and the heat value of our storage medium is known, it becomes a question of measuring the weight of the medium being used. When that is calculated all that is needed is just a measure of the total quantity of sunlight needed to heat the thermal masses of the heated portion to the desired temperatures, and then calculate that needed for the air cooled thermal masses.
Once the thermal masses reach their ideal temperatures, this system would be almost 100% free to operate. The only thing required would be once a year moving a vent and sunshine louver from winter to summer. That could be automatic. It could be made more efficient by automatically switching the louver positions based on weather predictions, but that is a refinement.
The physical mass for the thermal heat storage, of just about 72°F, is made of ordinary dirt, or sand, that has an insulation layer between it and our normal ground temperature of 55°F. This large volume of mass needs to have heated air flowing over or through it, and this mass would be placed directly under the floors. Thus the floors would automatically be at this temperature all the time; the wall could also be heated by having an inner wall a few inches inside of the exterior wall, with air ducts going from the mass below. To make the interior very temperature stable the ceiling should be very well insulated, and that would serve the additional purpose of taking the normal 72°F air of the room and making the ceiling that same temperature. This is much better than a typical heating system which sends highly heated air directly to the top of the room, which wastes this high heat by going out the ceiling.
This totally passive new system is the ultimate in ecological friendliness, because it is made entirely of low tech materials. It has zero ecological impact and it is free to operate and has only a few vents to be opened or closed every few months.