Environmental Comfort

This article will try to explain some of the environmental problems associated with living in a super-insulated dome home, and their related cures.

There are several conditions that contribute to the overall comfort in all primary housing, but there are some that need special consideration when applied to the dome home. The error in trying to adapt the same principles of comfort that might work in square housing to dome structures, in our experience, has been more than evident.

The comfort conditions of all residential housing require the following:

1. Temperature (heating and cooling).

2. Humidity (proper amount of moisture in the air).

3. Filtering (clean air is a must).

Control of these three items is essential to the creature comfort in all residential housing. Yet there are real differences in how they are accomplished.

Heating Systems

There are two basic methods of applying heat: forced air and radiant heat through baseboard and/or radiators. Both of these systems will provide heat. But the differences really become obvious when applied to dome structures. The best system, by far, for dome comfort, is the so-called forced air system.

One of the problems with dome heating is that convection currents carry the warmed air to the dome top. Since most dome designs include second floors, the experience tells us that those areas of the home will be too warm.

Most of the dome manufacturers here in the Midwest have found this to be true, and have corrected the problem in their design by providing in their general plans a return air duct in the upper portion of the dome. Though some heating contractors are reluctant to connect a single return air duct (they usually want to install a return air duct into every room), the fact remains that those heating systems that are designed with a single return air duct are performing exceedingly well in domes.

Some objections have been heard that the forced air system is noisy. It is true that in the past many installations of the forced air systems were noisy. However, that noise was usually caused by downsizing the ducts. The use of ducts that are too small forces the air to rush through the ducts, causing excessive noise. Enlarging the ducts virtually eliminates that objection.

The use of baseboard or radiant heating units makes the collection of that extra warmed air at the dome top impossible. Those extra BTUs are lost for all practical purposes. Unless a special fan and duct are installed, the upper portions of the structure will be too warm. Sometimes “casablanca” fans are used, but they are not very efficient and they have a tendency to cause uncomfortable drafts.

Humidity

The second primary requirement for comfort is that of humidity. Air that is too dry or too moist can cause a multitude of problems and discomfort. This feature of humidity control is easily adapted to the forced air system. The use of radiant heat systems requires additional special appliances to keep the humidity level in the comfort zone.

Filtering the Air

The third item in the comfort requirement is that of the filtering of the air. This is a given with the forced air system, as not only is the air filtered, but odors that accumulate inside of a home are quickly dispersed. Since filtering equipment is already built into the forced air system, there is no need to buy extra appliances to accomplish that end. The use of radiant heating systems require additional appliances to accomplish the same thing.

Cooling Systems

Dome cooling can best be accomplished using the forced air system, with he return air near the top of the dome. We are constantly being told by so-called experts that the cooled air should be introduced at the dome top. This violates a basic law of convection. When the cooled air is introduced at the dome top, it immediately begins to be warmed by sun, body, and appliance heat as it falls to the floor. Consequently, by the time it has arrived at the area where you live (you don’t live on the ceiling unless you are a fly), it has picked up some BTUs. Conversely, if that cooled air is introduced at the floor level where you live, using the same ducts that bring in the heated air, the condition temperature can be set a few degrees higher than it can be when the cooled air is introduced at the dome top. The reason is that at the floor level, you are closest to the evaporator (the cooling unit), which means that you are getting the full benefit from the cooling unit before the air has had a chance to be warmed, as it does when introduced at the dome top. This has a decided economic value in being able to run your cooling unit a few degrees warmer than you would with the cool air entering the area at the dome top.

Dome Top Heat Recovery Benefits

There is another benefit that has been discovered by using the dome top heat recovery system. In high ceiling structures, such as the dome, where no provision is made to move the extra warmed air from the dome top, there occurs a situation that can, at times, be very disturbing. That condition is the collecting of humidity on the inside (room side) of the vapor barrier. This occurs when the humidity in the warmed air reaches the ceiling, and condenses on the vapor barrier. It might seem that the roof is leaking when it had not rained for months. This situation can be corrected, in structures that have no air circulation as radiant heated homes, by the addition of a fan system that will move the air from the top. It is automatically taken care of with the forced air system, with the total return air from the upper part of the dome.

It is important that this information be given to the dome builder, as the problems related here are real. The solutions are relatively easy and cost-effective.