The building envelope, the boundary between the interior and exterior of a building, performs a number of tasks including exterior protection (e.g. protection from the elements) and preservation of internal space requirements (e.g. thermal, light, and acoustic comfort, humidity conditions). The use of a range of building technologies to create an energy efficient building envelope reduces both the thermal energy lost to the building’s surroundings and the amount of energy needed to heat and cool the building. Heating, cooling, and ventilation are responsible for around a third of primary energy use in the commercial and residential sectors, and energy represents approximately 30% of the typical office building’s costs. The technologies deployed can address a number of sources of energy loss such as air leakage, wet insulation, and thermal bridging. Installation options include:
- Building insulation
- Fenestration (i.e. windows, doors, skylights)
- High efficiency glazing
- Air sealing
- Cool/green roofing
- Advanced building facades
The amount of energy saved depends on the building and the technologies used, though ENERGY STAR buildings have been shown to reduce operating costs for corporate real estate owners by up to $25,000 per year for every 10,000 square feet of office space. Insulation and air sealing through effective air barrier systems can reduce non-residential building electricity consumption by more than 25%. Building owners interested in making energy efficiency improvements to their buildings typically conduct energy audits to determine the most cost-effective methods to improve the efficiency of the building envelope.
As buildings age, so does the building envelope and the materials. With the deterioration of materials, the performance of the building envelope also tends to deteriorate. This may have an impact on the energy efficiency of the building or it may pose safety risks. As such it is important to assess and understand the various systems, components and materials used before performance failure of the system or “near misses” occur. The long term sustainability of the building envelope is dependent on the measures that are in place to maintain the performance for the existing building envelope.
This paper provides an insight on the common materials used in building envelopes, common defects observed to building envelopes and then goes into more depth on how defects are assessed together with what measures should be considered in ensuring the long term sustainability of building envelopes in the design, construction and maintenance periods. The inspection of building envelopes is a key aspect in ensuring the long term sustainability of building envelopes. The presentation will then conclude with an example of how the condition of the building envelope can be monitored and maintained.