A sustainable façade should strike a balance between sound, light, security, heat, air, and views, as well as social equality and economic viability over time. To offer a comfortable and secure environment for building occupants, a facade must perform a number of functions, including providing vistas to the outside and protection from solar heat gain, noise, moisture penetration, rain and wind, for the inside.
Sustainable facades must prevent undesirable exterior environmental impacts, such as heat, light, and sound, and provide comfortable indoor conditions with minimum energy usage. Design choices for sustainable facades will be dependent on the context and climate while at the same time as minimising environmental impact and increasing the building’s performance. Sustainability aims include conserving non-renewable resources, recycling waste, and creating healthy, functional environments.
Setting meaningful energy performance targets early in the project stages help identify the many design possibilities. This can guide us on the site, building orientation, climatic conditions, and solar exposure. An early assessment of building energy performance prior to construction can help ensure costly design changes are prevented.
Architects and building engineers should integrate the design of building façades with other design considerations, such as material selection, daylight, heating, ventilation, and air-conditioning. The building location and climate, programme requirements, and site constraints should be considered while designing sustainable facades. Specific climate guidelines must be used when designing. When it’s hot and arid, different strategies are required than when it’s moderate or hot and humid.
A façade must be able to withstand the forces generated by wind loads while supporting its own weight and must adapt to daylighting measures in order to reduce reliance on artificial light. Façades today must also consider embodied energy and the energy consumed in the construction of a building and in the material extraction, processing and fabrication.
When we look at facades there are two basic elements in the design of any type of energy-efficient façade – orientation and fenestration.
The orientation of a structure dictates its exposure to sunlight. The earth’s angle to the sun fluctuates during the year and moves across the sky during the daytime, which means the solar exposure on a facade is constantly changing. Because the passive effects of solar orientation are so significant, the orientation of the facades should be considered early in the design process.
The building orientation is not always under the designer’s control however and it is often the configuration and orientation of the site, zoning or planning code requirements, or other similar considerations that will largely determine how a building is oriented.
Facades are classified as opaque or glazed. Opaque facades have a bigger mass, a higher level of insulation, and a higher rate of heat retention than transparent facades. Glazed facades may provide additional natural light to the interiors, improve occupant views, and impose reduced dead load on the building structure. These attributes are strongly influenced by the environment and the function, occupancy patterns, orientation, and equipment loads of a building. It is notable, in recent years, that new advanced façade solutions combined with plants have been developed to blend architectural characteristics and trends in order to reduce carbon emissions.
by Christine Espinosa-Erlanda