Retrofit : Volume 6 Issue 1 2017
38 • RETROFIT AUSTRALIA • VOLUME 6 NUMBER 1 | 2017 | Building Air Tightness I recommend is to very clearly delineate the different space types in your building. For example, clearly define public areas, office, commercial leases, residential space, sanitary areas, utility spaces and mechanical spaces. Mark these space types on a floor plan. This might sound like a waste of time, until you remember the overarching fact that what happens in one space will affect its neighbours. Defining different space types on a plan allows you to visualise their separation into airtight pockets so that ventilation can do its job, and it allows you to define a work scope to fix problems. If you are working in building management, you can probably recall examples of odour problems. We ventilate refuse rooms because we want the odours to leave, but a fact of building physics is that air always moves from an area of higher pressure to one of lower pressure, and those pressures change over time. A building is subject to the forces of wind, temperature, the opening and closing of doors, movement of elevators, and the operation of mechanical systems, so it’s hard to control air pressure. Mechanical solutions like exhaust fans are often relied on to solve problems. Drawing arrows and numbers on a mechanical diagram looks pretty, but unfortunately, without controlling the air pressure in the spaces they serve, you may have much less control than you are promised. Some examples of this include basement parking or utility areas, which should be hermetically sealed from the rest of the building. Energy savings are only a minor benefit – the gains in indoor air quality and fire safety should be enough to convince you. Make sure that doors are well sealed, but also check penetrations such as sprinkler pipes, ductwork, electrical conduits, and wall and ceiling joints, because these can transmit life-threatening smoke and fire. I couldn’t write an article about air tightness without mentioning the tools of building science. A blower door test, which uses fans to pressurise a building to quantify and locate air leakage, is an extremely valuable exercise for a building trying to improve comfort and save energy. It’s so effective that most advanced building codes require them for new buildings. If you look at the Air Tightness Testing & Measurement Association’s (www.attma.org) directory for international testing professionals, you’ll find many qualified Australian companies whose main obsession is building science. These folks can help you make sense of the sometimes daunting goal of controlling where air moves in your buildings. Retrofitting for air tightness doesn’t always mean buying new windows or re-insulating your building. Sometimes, it’s tasks like fixing vents and sealing basements that result in big gains. If you do buy new windows or upgrade the facade, make sure that you add a budget to inspect and test the work to get the benefits that you are promised – remember, we are trying to control air movement for the benefit of health, comfort and energy efficiency.
Volume 5 Issue 1 2016