The higher the R-value the better the insulation is at keeping heat or coolinside your house at a steady temperature - this is because it is better at not allowing the heat to pass through it (either going out or coming in).thus the term thermal resistance. R-Value is a measure of thermal Resistance. There are many types of insulation and they are all rated by one rating system and labeled with something called an R-Value. SO now lets focus on the first item on the list - the insulation. One other thing that the flow of air and moisture do is that they reduce the functional R-value of your insulation. (AND we will talk more about how to do that in another post.) We want to control where and when it goes in and out ot the house and we will do it though ducts and vents and other specifically planned appetures. We want to keep air and moisture from traveling through the walls. Air constantly wants to move through your walls and moisture travels on the air. Remember the laws of physics: hot moves toward cold, wet moves toward dry. All are bad! bad! bad! for a house! never mind you the occupant. The reason you want to keep moisture and air from flowing back and forth through your walls is that air and moisture are the very things that cause building material deterioration, mold and mildew and dust (major allaergens), dust mites (which lead to spiders), insects and critters, etc. The last 3 have to do with preventing the flow of air and moisture through the walls and are addressed through caulking and flashing and various tapes and sheet barriers (think Tyvek- tho we don't use Tyvek exactly). Ok - back to the rules of the envelope list: a) very well insulated b) very well sealed by filling any holes, penetrations, nooks and crannies and cracksc) protected from moisture infiltration and d) protected from air infiltration. YOU want to control when and where air and moisture come and go. You would have to continually fill the pool and constantly adjust and observe water levels, and all sorts of problems would occur in the area of the cracks (the cracks get bigger, deterioration of the liner occurs faster, dirt and critters collect there,etc, etc.) You want the same for your house. If your pool was full of little cracks you would have no control over the water. If you own aswimming pool, you want to be in control of when the water leaves or enters your pool. It is a given- like breathing- no architect or builder who builds well built, well insulated, well sealed houses will ever 'forget' to provide fresh air (unless they are a completely crazy or utterly incompetent and you will have noticed that long before you get to the building sealing stage! )īasically I always use my swimming pool analogy. AND just to ease your mind- addressing the air exchange in a well sealed house goes hand in hand with sealing the house. the bottom floor/ slab/ basement/ crawlspace (whichever the case may be.) So the first goal is to make that envelope a) very well insulated b) very well sealed by filling any holes, penetrations, nooks and crannies and cracksc) protected from moisture infiltration and d) protected from air infiltration.Ī lot of people's reaction to this is 'I don't want to live in a sealed box!' or 'Isn't it bad or dangerous to completely seal your house?' while it is true that a house needs to be sealed with care and that concerns about air exchange need to be addressed, you actually do want a well sealed home. What does that mean? Well, when we say envelope we mean the outer shell of the house. The number one basic rule in creating an energy efficient building is 'first address the envelope'.
0 Comments
Leave a Reply. |