Building Science - Physics Affects Your Comfort
A house is more than four walls and a roof. It is an interactive system made up of many components: Structure, Insulation, Ventilation, and Filtration. Each component influences the performance of the entire system in predictable ways, if we consider four simple principles of physics.
1. Moisture movement:
Moisture levels in a home depend upon a variety of factors. It can be as simple as the number of showers taken a day, or the number of meals prepared in the kitchen. If we include the number of household members, leaks, and ground/atmospheric moisture that provides us with starting blocks of understanding moisture movement within a house. Generally, moisture wants to move from areas of high vapor pressure to areas of low vapor pressure. For example, when the home is being heated, moisture wants to move to the outside, and when it is being air conditioned, moisture tends to be sucked in.
Relative humidity (RH), the a percentage of moisture in the air compared to the total capacity of the air to hold water is limited by air temperature. RH increases when temperature decreases and goes down with higher temperatures. This concept becomes an important aspect of controlling moisture in our homes.
2. Dewpoint temperatures:
The dewpoint is the temperature where water vapor condenses to liquid water. This is a function of both temperatures and the amount of moisture in the air. If we have a dew point of 40 degrees, any surface in the home that reaching 40 degrees will have liquid water on it. To prevent this condensation, we can either raise the surface temperature or lower the relative humidity by increasing the temperature of the air.
3. Pressures:
Air moves from areas of high pressure to areas of low pressure. Combine this concept with holes in our homes and you will see a pattern of air movement develop. This affect is of great concern in residential construction, and provides a basic understanding how our homes function.
Pressure differences are created by outdoor wind and temperature and indoor exhaust fans, air handlers, chimneys and vents. Pressures influence house performance. If there is a hole available to allow the air to travel from a high pressure to a low pressure in a house we may feel a draft in the winter. Remove the hole, the air will not move and the temperature stabilizes.
We feel cold air coming in but usually never notice all the hot air leaving our home. Air leaking out generates problems with attic and wall condensation in cold climates and ice dams in climates with heavier snow loads. Echohomes solves the problem of the moving air by sealing the home to remove the pressure differential.
4. Heat flow:
Heat, like pressure, moves from higher temperature to areas of lower temperature. In winter, without adequate insulation our heat escapes outside. In the summer we fight to keep the heat of the day from moving to inside. To resist this heat flow we install insulation in the walls and attic of our home. Insulation strength is measured as an R-value. The higher the R-value the better the insulation minimizes heat flow.
The three types of heat flow we address are:
Conduction: Heat transferred between objects that are in contact (touching a hot iron is one form of conduction)
Convection: Heat transferred by movement in gases and liquids (a hair dryer moves heat this way)
Radiation: Infrared spectrum heat transfer, which occurs even in the vacuum of space (that's how the sun's warmth reaches us)