Buildings Guide

Building Envelope

Key Message

Optimizing building envelope properties results in efficient regulation of the heat transfer between the building’s exterior and interiors. Critical parameters in the building envelope include thermal performance of the exterior walls, roof, ground floor slab and fenestrations, and the air tightness of the buildings. The performance requirements of envelope parameters depend on factors such as cooling and heating demand, the mode of the building, i.e., whether the building is open, closed or hybrid. In combination with high levels of air tightness, reduced thermal bridging as well as high performance windows, savings in heating energy of up to 75-90% are possible in cold climates. In regions with mild winters, the need for winter heating may be eliminated altogether. Cooling loads can also be reduced by about half in hot climates and eliminated in regions with mild summers, if internal loads and solar gains are minimised.


The building envelope is the shell or skin of the building, through which the heat transfer, between the outside and the inside of the building, takes place. Building envelopes should minimise the negative impact on internal thermal comfort conditions through the influence of the external climatic conditions. In cool climates when internal spaces are heated, it is very important to make sure that the heat cannot escape through the building’s envelope. In hot climates, it is equally important to make sure that the outside heat cannot penetrate too easily into the internal spaces, thus increasing the cooling load. Energy savings due to optimized building envelope are more pronounced in buildings with considerable heat transfer through envelope compared to internal heat gains. Theoretical and practical application of efficient building envelopes has been proven a success especially in North American and European residential buildings.


Key parameters that influence the performance of building envelope are the thermal properties of opaque elements of building’s outer shell such as exterior walls, roof, on grade floor slab, doors; transparent elements such as windows, skylights; weak elements of heat transfer called thermal bridges and the reduction of infiltration by improving the air tightness of the buildings. Although these parameters need to be optimized, their design and exact specifications and cost effectiveness are highly dependent on the buildings function, mode and climate.


  • Johanna Knaak
  • Sriraj Gokarakonda
  • Christopher Moore


  • Greg Scutt
  • Stefan Thomas


  • Harvey, L. D. D. (2006). A handbook on low-energy buildings and district-energy systems: Fundamentals, techniques and examples. London: Earthscan.

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