The building envelope is a significant contributor to heat gains and losses for buildings. The actual percentage obviously depends on many factors, including orientation, building location, etc. but can be as high as 30% or more. This simple fact highlights the need for a concerted design of building façades between the architect, façade consultant, ESD consultant and mechanical engineer.
Simple decisions at an early stage have the greatest impact on the overall envelope performance, at the lowest possible cost.
For instance, selecting the optimal building orientation has very little cost implication, if any at all, while having massive effect on the energy bill of the building. Similarly, adopting optimal window-to-wall ratio can allow outside views and harnessing of daylight, while severely reducing heat transfer, all of it at virtually no cost to the developer. A number of such strategies can be implemented, but all require the early involvement of the façade and ESD consultants right from concept stage.
Working with the façade consultant, the ESD consultant may deploy a number of tools, such as whole building energy modelling and ROI computations, to test various combinations of façade materials and performance, shading strategies, window-to-wall ratios, etc. so as to assess the most viable solution for a specific building. Once again, this requires teamwork and close coordination between the architect, façade consultant, ESD consultant and mechanical engineer.
Occupant comfort is another area where the project façade and ESD consultants must work closely together. The ultimate goal is to ensure that the building is liveable, and pleasant to its occupants. For residential buildings, this may involve carrying our CFD studies in order to determine the optimal opening sizes and locations, so as to harness available wind to cool internal spaces at no or minimal cost.
For commercial spaces, the aim is to achieve thermal and visual comfort, ensuring that building occupants, especially those located close to the façades, are not subjected to excessive radiant heat or glare. Specific tools are available to ESD consultants to carry out such studies.
Over the past 10 to 15 years, the performance of building façades has progressed tremendously.