Welcome to the Energy Efficiency Myths series from Direct Energy! As many myths arise from incomplete knowledge, they can create seemingly possible answers that many people accept as fact. Each month, we will examine common misunderstandings about energy efficiency — whether it’s in your home or about the energy industry — and deliver real facts behind the myth (and how they they might be costing you money).
Air sealing and insulation make houses too tight. Homes need to breathe!
This energy efficiency myth came to life in part because of the passive solar/super-insulated homes designed in the 1970’s – even though these wound up having severe moisture and mold problems.
Thanks to updated research into how the movement of air impacts the energy efficiency of a home, we now know that eliminating drafts, air sealing your home, and installing the correct amount of insulation will go a long way to keeping moisture out of your home.
However, all the water vapor in your home needs to be able get out, too. Moisture gets into houses in three main ways: air currents, diffusion through materials (including wood and concrete), and by heat transfer. Moisture gets in when it rains, from the ground underneath your home, and also from humans – we produce LOTS of water vapor just from the business of living (cooking, showering, and even just breathing). When moisture becomes trapped, like inside a wall for example, that’s when real problems arise.
What should I do about moisture in my home?
Unfortunately, the average relative humidity of a given climate varies in different areas of the country.
- Northern climes in winter have cold outside air hitting warm humid conditions inside the home, and this causes condensation problems inside the walls.
- Southern climes in summer have hot, humid conditions outside and dry, air-conditioned interiors, which causes condensation problems the inside walls.
- During wintertime conditions in dry climates, drafty homes tend to dryer inside, while in wetter climates, drafty homes will tend to feel dank and have more mold problems.
How do you control moisture?
In most houses, water vapor exits by diffusing through the ceiling, entering the attic, and exiting through vents. There’s usually not enough relative humidity moving through the sheetrock to cause mold growth in attic insulation. Other exits include bathroom and kitchen ventilation fans.
Air movement or drafts account for 98% of the water vapor entering your home, as it moves from high pressure or wetter areas to low pressure or dryer areas along paths of least resistance. The better the attic is air sealed from the living space, the dryer it is, and the less chance for humid air to build up in the attic and turn into a mold problem.
Apart from sealing against drafts getting into your home, look for places where water might enter your home, such as rain gutters or downspouts that leak into your basement. Make sure the downspouts carry water well away from your home.
Look for water damaged siding, as well as windows and doors that don’t close properly. Be sure that bathroom and kitchen ventilation fans blow exhaust outside the home. Floor drain traps can also dry out and allow water vapor to enter your home that way. It’s a good idea in the winter to pour a little water into them once month to keep the traps filled and sealed.
For more information about proper air sealing to improve the energy efficiency of your home, check out this blog post as well as the Energy Efficiency and Home Improvement sections of the Learning Center.
Do you know of any Energy Efficiency Myths you’d like us to dispel? Share with us in the comments!