Publish Time: 2023-05-15 Origin: Site
A damper is a machine used to measure the airtightness of a building.It can also be used to measure airflow between building areas, test the airtightness of ductwork, and help physically locate air leaks within the building envelope.A blower door consists of three main components:
(1).A calibrated variable speed blower or fan capable of producing airflow sufficient to pressurize and depressurize various building sizes.
(2).A pressure measuring instrument called a pressure.
(3). A mounting system for mounting the fan in a building opening, such as a door or window.
Air tightness testing is generally considered in residential environments.It is becoming more and more common in business environments.GSA Requests Testing of New U.S. Federal Government Buildings.Various blower door tightness metrics can be generated using a combination of building exterior pressure and fan airflow measurements.These metrics vary in their measurement methods, calculations and uses.Building researchers, weathering crews, home performance contractors, home energy auditors, and others use the blower door test to assess the construction quality of a building envelope, locate air leak paths, assess the amount of ventilation provided by an air leak, evaluate to determine whether a building is too tight or too loose, determine whether a building requires mechanical ventilation, and assess compliance with building performance standards.
A basic blower door system consists of three components: the calibrated fan, the door panel system, and the pressure measuring device (manometer).
Test setup
Temporarily seal blower door fans to exterior doorways using a door panel system.All interior doors are open and all exterior doors and windows are closed.HVAC balance dampers and regulators must not be adjusted, and fireplaces and other operable dampers should be closed.All mechanical exhausts in the home, such as bathroom exhausts, kitchen range hoods or dryers, should be turned off. Piezometric tubes are used to measure fan pressure and also lead to the outside of the building to measure the difference between indoor and outdoor pressure.External pressure sensors should be protected from wind and direct sunlight.The test begins with sealing the fan face and measuring the baseline indoor/outdoor differential pressure.The average value shall be subtracted from all indoor/outdoor differential pressure measurements during the test period.
Test program
Blower door fans are used to blow air into or out of a building, creating a positive or negative pressure differential between the inside and outside.This pressure differential forces air through all holes and perforations in the building envelope.The more compact the building (eg, fewer holes), the less air the blower door fan will need to create pressure changes in the building.Usually only a decompression test is performed, but it is best to perform both decompression and pressurization at the same time.Due to the response of the building envelope to directional airflow, different values are expected for the blower door indicators for pressurization and depressurization.The smallest fan ring that allows the fan to achieve the maximum target indoor/outdoor pressure differential should be used.Multi-point testing can be performed manually or using data acquisition and fan control software products.Manual testing involves adjusting the fans to maintain a range of indoor/outdoor pressure differentials and recording the resulting average fan and indoor/outdoor pressures.Alternatively, a single point test can be performed where the blower door fan is ramped to a reference indoor/outdoor differential pressure and the fan pressure is recorded.Typically, the blower door hardware will convert fan pressure measurements directly to fan airflow values.