By Siva Davuluri
Canada is famous for many things, including hockey, maple syrup, and stunning landscapes. Its large temperature swings and harsh winters are as well-known as Niagara Falls. Even temperate southern cities like Toronto see average monthly temperatures drop more than 25 C (77 F) between peak summer months and the dead of winter. This number grows to more than 30 C (86 F) for cities like Québec, Montréal, and Edmonton, and nearly 35 C (97 F) for Winnipeg.
Regardless of location, air leakage and air exchange are two of the biggest issues facing architects, designers, and facility managers when it comes to specifying commercial rolling doors for conditioned warehouse spaces across the country. This is a direct result of a larger trend toward increased energy efficiency for industrial and commercial buildings along with tougher standards such as Canada Green Building Council’s (CaGBC’s) Leadership in Energy and Environmental Design (LEED) v4.
After all, the longer a door is open and the weaker the seal around it is, the higher the likelihood of air exchange and thermal loss. This effect is magnified when temperatures dip below the freezing mark.
However, recent developments in high-performance doors can contribute to more energy efficient construction with a combination of operational, maintenance, safety, and sustainability benefits, thereby preventing:
- heat exchange through prolonged opening of the door;
- thermal loss due to inadequate insulation when the door is closed; and
- maintenance downtime because of complex service needs.
To improve energy efficiency and save time and money as well as meet increasingly stringent environmental laws and regulations, industry professionals are turning to high-performance doors.
The Door and Access Systems Manufacturers Association (DASMA) defines a high-performance door as “a power-operated rolling, folding, or sliding non-residential door, generally characterized by either 100 or more cycles per day or 20 or more inches per second opening speed, and typically made-to-order and/or designed for higher durability, and/or designed to break away due to equipment impact.”
Code-exceeding energy efficiency
The American National Standards Institute/The American Society of Heating, Refrigerating and Air-Conditioning Engineers/ Illuminating Engineering Society (ANSI/ASHRAE/IES) 90.1-2016, Energy Standard for Buildings Except Low-Rise Residential Buildings, the 2015 International Energy Conservation Code (IECC), and the 2015 International Green Construction Code (IgCC) are important energy saving mandates for commercial and industrial facilities.
In the near future, it is likely the definition of a well-designed building will include the attainment of net zero-energy usage.
Products combating air leakage offer tools to achieve conservation goals by reducing heat exchange and increasing thermal efficiency, thereby decreasing the environmental impact and energy usage of the building.
Many design and building professionals do not realize the latest code requirements identify stringent, non-negotiable standards for acceptable air leakage, defined at a constant value of 0.25 L/s-m2 per the the Building Energy Performance Compliance Path, sub-section 8.4 of Division B of the National Energy Code of Canada for Buildings (NECB).
Contrary to popular opinion, these are not optional standards to be “greener.” The new regulations are mandatory, and a trade-off path to approval is not available. Further, products must have third-party certification (e.g. Building Owners and Managers Association [BOMA] of Canada and the U.K. Building Research Establishment’s [BRE’s] Environmental Assessment Method [BREEAM]) to substantiate compliance.
Exterior rolling door manufacturers are developing products to meet these new performance goals.
In the past, rolling doors were selected for their space-saving benefits, security, reliability, and durability. Design professionals are now choosing them for their energy efficiency as well since some models meet or exceed ANSI/ASHRAE/IES 90.1-2016 and IECC’s air infiltration requirements with air leakage value of less than 0.01 cmm/m3.
Controlling air infiltration
Thermal resistance and air leakage are often inter-related. Key air leakage areas for a conventional rolling door are at the head and along the guides. Since metal has high conductivity, energy efficient doors with metal frames should include thermal barriers in the guides to reduce conduction. Frames without thermal barriers reduce the energy efficiency of the entire building envelope.
Doors designed with advanced perimeter seals, thermally broken frames, and insulation offer increased air infiltration control. Additionally, these perimeter seals can accommodate odd floor and wall conditions, including slopes, curbs, or rails, and doors can be designed to meet specific installation requirements to provide an energy efficient enclosure for new construction or retrofit projects.
Some rolling doors can decrease air infiltration by as much as 95 per cent, and manufacturers estimate savings of up to $1215 per door with a two-year return on investment (ROI) when selecting an energy efficient rolling door for the appropriate climate zone.