Our #1 Priority!
Energy Efficiency is a major concern today and Spray Foam insulation is revolutionizing the way we design Thermal Envelopes. Many people are having a difficult time paying for the ever-increasing energy bills. Natural Gas has doubled within the last 3 years within our state alone. The good news is, you can easily upgrade to affordable spray foam thermal envelopes. For years we have been misled by claims that R-value is a useful performance measure. Today, we now know Air Changes Per Hour or ACH has much more to do with the performance of insulation. Spray foam solutions allow for a complete airtight seal and will eliminate unwanted air leakage in your home.
What is R-value and why doesn’t it work?
R-value is a measure of thermal conductivity expressed in kelvin square meters per watt (K*m2/W). The test method is defined by ASTM C518. In short, the conductive resistance of the insulation material is measured at 75F in an environment without wind. The problem with this method is that it is not very relevant to real-life situations. In particular, fiberglass shows peak performance at 75F, while its performance is seriously diminished at 35F or 105F, while foam shows hardly any deterioration. Likewise, homes are not in wind-still environments, and are often subjected to pressure differentials between indoors and outdoors due to temperature differences, forced air heating and cooling systems, etc. As such, we feel that Air Changes per Hour (ACH) is far more relevant than R-value in determining insulation performance.
What is ACH and why is it important?
Air Changes per Hour = ACH. This is a measurement of air infiltration, which is the total amount of air lost through the building envelope. The analysis is done with all windows and doors closed and a simple device called a Blower Door with air pressure measure devices. Very tightly constructed homes with spray foam insulation may achieve an ACH of 0.1, while properly constructed homes insulated with fiberglass may reach values between 0.7 and 1.0. The ACH of older, poorly maintained homes may be higher than 2.5 (my home tested at 7 ACH built in 1978). What this means is that homes insulated with foam lose their air 2.5 times per day compared with 17 times for homes insulated with fiberglass, and up to 60 times per day for old homes without insulation.
Air Tightness guidance:
This is very important concept to understand, because if we are paying for heating and cooling or conditioning the air in our homes, we are essentially throwing money out the windows given our traditionally insulated homes leak .7 ACH per Hour or 17 air changes each day. A home with R-15 spray foam in walls and roof will outperform any amount of traditional insulation R-values due to Air Tightness.
Many products one the market today tout themselves as airtight. Soon we will have airtight electrical wiring, but the installer will still drill large holes in faming members to pull his wire and we have made zero improvement. Image how difficult it can be to create airtight thermal envelope, blow up a balloon, tie a super tight knot, what happens over night. One common answer I get from people in the construction industry is my house is air tight because we use stucco. While this has some minor support, you have to think the home is a system of many components. If we cut holes in our roof (roof vents) and holes in our soffits (continually around our homes perimeter) you have to begin to think there is many places for our homes to leak. One of my favorite questions during a Blower Door test is: Why is air coming out of all of my interior wall outlets and wall switches? Simple, air in the attic is directly connected to the outside, this air leaks into virtually every part of the home and its path of least resistance is the outlets and switch plates.
Air leakage and path of least resistance (the boat story):
Image if you were in a boat and unfortunately we had ten small holes in the bottom, they would all be spaying up water and the boat would slowly sink. As you frantically begin to fix these holes you notice the last hole is spraying up much higher than when you had the other 9 leaking. Interesting? Now image if I work really had to make my walls air tight and leave the many other components like attics, rim joists, etc as we always have. Would you be effective in your mission to create an air tight home? No not really, because the other components would just leak more to make up the difference of your air tight walls. So when considering air tight construction you must consider the entire system of components, walls, rims, roof, etc. or you are really making very little gains of improvement.
Common misunderstandings – Air Tightness:
Building wraps (common brand Tyvek) are often touted as providing an air tight home, they are in fact now labeled as an air barrier. Really they are nothing new in the construction industry, I have taken many homes apart that were built at the turn of the century (1900), and they all had some type of building wrap that served them well. These building wraps, new and old, offer little in the way to creating an airtight home. However they do server an important role as a Drainage Plane. A Drainage Plane serves as the home’s rain jacket, which if installed correctly severs as an important step towards keeping water out of the home. Two primary reasons why building wraps do not provide a consistent Air Barrier:
Ice Chest Example – Air Tightness
With just ½” of foam and R-value = 2 your drinks will stay cold with ice for 2 days. If the top is not shut and air is allowed to leak, you will probably lose your ice in ½ a day or less. The lid is providing a barrier to air infiltration.
