The First Step In Making Your Home More Comfortable
Blower Door Testing
A basic energy assessment includes a blower door testing which gives homeowners a big picture understanding of air movement in the house. By using this method we will help determine areas where heated air escapes. Because a blower door uses a fan to create negative pressure in your house or slightly depressurize the house, outside air is pulled in through gaps, making them easier to find with our infrared cameras.
A blower door test is a standard measure of the leakiness of the house to air. This air infiltration accounts for as much as 40% of the cost of space heating for old, leaky houses. The blower door test allows us to:
- Measure the air leakage for comparison to other houses and for evaluating the effectiveness of air-sealing operations.
- Estimate the energy costs of natural air infiltration throughout the year.
- Find the worst air leaks so that they can be sealed.
- Ensure that minimum ventilation levels are maintained, as each home needs some ventilation and fresh air for good indoor air quality.
The blower door equipment blows air out of the house and depressurizes the house to 50 Pascals (Pa) relative to the outside, and measures the airflow through the blower door fan required to maintain this level. This is the amount of air leaking into the house through gaps, cracks, joints, or directly through some materials. The pressure 50 Pa is equal to 0.2 inches of the water column, or about 0.007225 psi, roughly the pressure exerted by a moderately strong wind blowing against the house.
Several forces drive the air movement through the building shell:
Stack effect: Warm air is less dense than cool air, and naturally tends to rise in the house (just as a hot air balloon rises), while cooler air falls. This rising warm air creates increased air pressure at the higher levels of the house, and the warm air is forced out of the house through any openings. This forces cooler air to be drawn into the house at lower levels. The stack effect pressures are greatest at the highest and lowest points in the building. Therefore, a hole in the basement or attic will allow more air infiltration than an equal-sized hole near the middle of the house.
Wind pressure: Wind blowing against a wall creates an area of high pressure, driving outdoor air into the windward side of the home. The wind creates a low-pressure area at wall and roof surfaces parallel to its flow, and the leeward side, facing away from the wind, is usually either neutral or depressurized, allowing air from the house to escape.
Chimney and exhaust pressures: Chimneys, exhaust fans, and clothes dryers create a slight depressurization in the house because they exhaust air out of the building. In many cases, this can’t be avoided, of course. However, gas-burning appliances that are sealed combustion avoid much of the chimney pressures because they use outside air for combustion and vent the combustion gases through sealed vents. These appliances don’t rely on any air from inside the house to create the draft necessary to vent dangerous combustion gases to the outside.
Duct pressure: The furnace or A/C blower circulates air through the system’s supply and return ducts. If the ducts are leaking, or if return air (air meant to return to the blower to continue the cycle) is restricted, rooms may have a high positive or negative pressure, which can help to drive air through the building shell. These pressures are often large enough to double or triple the building shell’s air leakage compared to when the blower is off.
Test Data: The measurement obtained from the test is the flow rate in cubic feet per minute (CFM) at 50 Pa of pressure. This is the CFM50. Using this value, along with the calculated volume of the house, the Air Changes per Hour rate is calculated at 50 Pa of pressure (ACH50). Then, using well-established formulas, an estimation of the natural air changes per hour is given. These formulas take into account the average temperatures and wind speeds in an area (colder and windier areas allow more air leakage), the building’s height (a taller building allows more leakage), and the shielding of the building against the wind (the better the shielding the less wind and then the less air leakage). The natural air change rate is denoted by ACHn or just ACH. For example, an ACH of 0.5 means that every hour 50% of the air in the house is changed due to air infiltration. Of course, this air coming in must be heated by your furnace or boiler.
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Infrared Thermal Imaging
With Infrared thermal imaging cameras, our technician can graphically display and photograph the insulation levels and cold or hot spots within your walls, ceiling, floors without creating any holes. Most people are amazed when they see a vivid image of where they are missing insulation and what that does for heat loss in the winter or heat gain in the summer. You will be too! This is why an energy assessment is so important.
Minimum Ventilation Requirements (MVR): In order to maintain acceptable indoor air quality, some fresh air is required. In leaky homes this is easily accomplished through the building shell. However, for especially tight houses mechanical ventilation is required. Typical standards require that air leakage provides either 15 CFM per person or 0.35 ACHn, whichever is greater.
Thermal imaging helps to diagnose the problem rather than merely identify symptoms and can sometimes, but not always, identify and document: Electrical faults before they cause a fire, overloaded and undersized circuits, circuit breakers in need of immediate replacement, missing, damaged, and/or wet insulation, heat loss and air infiltration in walls, ceilings, floors, windows and doors, water and moisture intrusion that could lead to mold, possible pest infestation, hidden
roof leaks, before they cause serious damage, air conditioner compressor leaks, under fastening and/or missing framing members, structural defects, broken seals in double pane windows, energy loss and efficiency, dangerous flue leaks, damaged and/or malfunctioning radiant heating systems, unknown plumbing leaks, and overheated equipment. These color images can then be included in your IR inspection report providing supporting documentation to the report. This the imaging technique is a powerful and noninvasive means of monitoring and diagnosing the condition of buildings. IR inspections can provide immediate documentation of as-built & post-restoration conditions, post-damaged material assessment, energy inefficiency, and electrical problems. Typically, moisture on building materials will evaporate and cool by as much as 39 degrees Fahrenheit. A wet spot (when observed with infrared camera) is clearly visible as a distinct cool spot.
If you have any questions, please do not hesitate to contact us.
Corner wall had a major air infiltration, can be solved by insulating all exterior walls with blow in cellulose under high presure.
Ifrared image discoverd missing chimney insulation, air seal and blow in rookwool was recomended.
Infrared image help discovered bad weatherstrip which was replaced by Green Attic Insulation.
Infrared image of missing wall insulation and cold air infitration by outlets, Green Attic did blow in cellulose dense pack and foam aroun outlets.
Pull-down ladder had litle to no R-value, and allowed warm moist air to escape in to the attic, Green Attic built a 12 inch wall with a R-39 insulated plywood door on top.
Rim joist cold air infiltrating infrared image Green Attic needs fiberglass removal and insert foam boards and seal with foam.