Characteristics of Sustainable Building Envelopes

Building envelopes in sustainable buildings are different from conventional buildings in that they aim to achieve a wider range of objectives and work in a different way.

Some characteristics of sustainable building envelopes are:

1. Responsive: Green building envelopes are designed to respond to their local context and work with external and internal conditions to achieve optimum environments within and around the building. Therefore, the building envelope may have additional acoustic treatment in areas which receive noise from external environments and have strong visual and physical connections (through balconies, windows and external doors) where external light and thermal conditions support human comfort.  
2. Dynamic: In order to achieve optimum conditions on an ongoing basis, green building envelopes are dynamic and adapt to changing conditions. Thus, more of the building envelope may have shading in summer than in winter to minimise unwanted heat gains. In winter, the envelope may allow more sunlight to enter the building than in summer to allow this to warm the building.  
3. Controllable: Providing users with greater control over local environments is a central strategy in most green buildings. Building envelopes, therefore, are likely to have large numbers of operable windows that can be easily opened and closed by occupants. They may also have controllable internal blinds and external solar shading which can be used to maximise internal daylight quality and avoid glare and solar gain. 
4. Ecological: Green building envelopes aim to support the development of ecosystems and plant and animal life around the building. Therefore, the envelope may be used to create habitat for animals such as birds and the roof and balconies may be planted. 
5. Breathable: Designers of green building often try and achieve the same performance qualities found in good outdoor clothing. The outer layer of the building envelope, like a raincoat and umbrella, provide protection against weather such as wind and rain. The middle layer, like shirts and jerseys, provide warmth and thermal insulation. The inner layer, like a vest, is comfortable to touch and wicks away excess moisture. 
6. Microclimatic: The building envelope is used to support the development of local microclimates. Thus, envelopes may be used to create sheltered, sunlit spaces around buildings as amenity areas for occupants.  They may also be used to create vegetated, shaded areas from which cool, fresh air can be drawn into the building. 
7. Energy generation: Building envelopes provide excellent opportunities to generate renewable energy for use in the building. This is done through photovoltaic and solar water heating panels and wind turbines. Ideally these are integrated in the design of the building envelope to improve the aesthetic quality of the building and minimise material requirements. 

A brief introduction to sustainable building envelopes can be accessed here.