What is the difference between blower door test and energy audit, and why do I need it?
A home energy audit is a wonderful thing. So valuable. But who does them, and how do we know if they are going to use it to highlight a product they partner with or sell? Green Attic customers have expressed difficulty finding reliable answers and great, honest, knowledgable auditors. They are out there, but there are very few. We are one of them.
An energy audit generally consists of air leakage detection and identification, insulation evaluation, house heating system evaluation, water heating evaluation, appliance evaluation, computer and electronics evaluation, doors and windows, evaluation, lighting evaluation, personal habits, blower door test for CFM and ACH, and a summary report.
Green Attic focuses on the customers concern, the reason for the call, so the general items listed on a typical audit may or may not take center stage during the audit. The homeowner relies on us to direct the conversation towards truth, fact based building science, and energy conservation.
Green Attic has found the most common deficiencies are already visible without a blower door test and thermal imager. The thermal imager will confirm to our eyes what we are already feeling. The thermal imager will confirm unintentional gaps in the pressure barrier ( air barrier or building envelope).
Two proven facts, where there is air infiltration / heat escape, there is cobwebs / and or cracked caulk and paint around cometic seams. The caulk or paint is the last line of defense against air intrusion, and due to temperature differences, it is inevitable. Visit after visit, house after house, same indicators, same information, same proof.
Green Attic starts with an exterior property walk. We locate impactful unintentional gaps in the building envelope. Example, window frame to siding / brick not caulked. Sometimes is missing, sometimes its cracked, sometimes is poorly applied / partially applied. The resulting air intrusion comes through the path of least resistance ( think water / energy ) such as wall outlets and most commonly base shoe / baseboard trim.
Green Attic will locate gaps between building materials such as siding to foundation, window frame to window, facia to brick, and more. These gaps are unintentional, treatable, and highly impactful in reducing a series of resulting problems such as air quality, uncomfortable rooms, higher than neighbors heating and cooling costs, and more.
Green Attic can target exact location of air intake from the exterior and recommend a treatment solution for exterior sealing. We can prioritize treatment, and create an action plan with prices and individual line items for treatment. Some items can be performed by our attic insulation team, while others require a handyman, painter, siding contractor, or another specialist in the respected field.
Green Attic will walk the home under normal living conditions, and measure ductwork vent delivery temperatures. We may find a leaky duct or poor pressure or temperatures to conditioned air supply in a particular space. We may find significant gaps along the baseboard. We may find obvious heat escape such as can lights which have no AT rating, and usually there will be corresponding cobwebs. We may find heat escape from top plates ( bypass between framing top plate and drywall seam).
Green Attic will locate unintentional air leakage and provide a solution. There are many variables to air sealing, both interior and exterior products, and application methods. For example if the floors are wood and the trim is white ( common decorating style 2010- present) clear caulk will be used on that seam, while the seam between base show and base trim will be white caulk.
Green Attic will calculate the sq ft of the home and volume ( cubic ft volume) and determine the ACH ( air exchange per hour). This is a valuable number for new construction / remodel as is is most commonly required to be at 4.0 in order to receive occupancy permit.
Additionally, Green Attic will take a CFM (cubic feet per minute) reading to measure how many cubic feet ( about a basketball in size) of air is being drawn through the blower door test fan while depressurizing the home to 50Pa ( pascals). Most homes in the Chicagoland area which have average deficiencies test between 8-12 ACH. With 4.0 being the baseline for occupancy of a new home, we are 2-3 times leakier than intended, translation to 2-3 times less comfortable, 2-3 times higher heating and cooling costs, but that is subject to other relative variables such as insulation, building construction methods and materials and more.