Controlling Energy Use Through the Building Envelope
A facility’s building envelope can make or break utility bills and energy-efficiency goals. As a barrier that keeps indoor temperatures inside and outdoor temperatures outside, the building envelope includes the foundation, exterior walls, insulation, roof, windows, and exterior doors. The quality of the building envelope can also impact indoor air quality and humidity levels, and have an effect on water infiltration.
To determine what your building envelope is (or isn’t) doing for your energy expenses, investigate the following building systems:
Evaluate the roof’s thermal performance regularly, including its Solar Reflective Index (SRI), which indicates reflectance and emissivity. A roof with a high SRI reduces the heat island effect caused by acres of black asphalt roofs and other dark surfaces that absorb heat, causing urban areas to be hotter than nearby rural areas. Cool roofs and garden roofs are also building envelope options that offer energy-saving advantages over traditional black roofs.
Examine all existing windows and check for condensation, air leakage, broken glass, etc. Making the financial justification for window replacement can be tough due to high initial costs and long ROI periods, but high-performance, low-e window film could be a viable alternative. If windows are found to be in good condition, window film can help improve their insulating power. In addition to helping reduce solar heat gain during summer months, the right low-e window film can also help decrease thermal heat loss through windows, keeping indoor spaces warmer in winter months. Window film helps maintain interior temperatures and helps reduce hot/cold spots throughout a building as well.
Heat loss from air leakage is the biggest thermal challenge for commercial doors, along with moisture protection. Make sure exterior doors close tightly, and aren’t being propped open to counteract uncomfortable temperatures (this is a huge waste of energy). Routinely examine weatherstripping between the operable sash and the doorframe, as well as flashing. Revolving doors can also be considered as an energy-saving option for exterior entrances/exits; they may minimize HVAC losses and help regulate heating and cooling loads.
Check the building’s existing cladding system. If it is deteriorated and performs poorly, it may be time for removal and replacement, or for over-cladding (installing a new cladding system over the existing system). In some cases, the space between the initial cladding and the new cladding can be used to pre-heat or pre-cool exterior air before it enters the building.
A well-insulated building envelope can have a powerfully positive effect on your facility’s energy efficiency. Keeping up with regularly scheduled roof, window, door, and cladding maintenance and repairs can help these systems last longer and keep exterior elements where they belong – outside!
How do you keep tabs on the performance of your building envelope? What envelope upgrades have you made recently to improve energy efficiency?