A sustainable building could be any building, as long as it integrates sustainability principles. Such principles work when systemic and holistic to the project, as they range from energy efficiency to health and wellbeing, climate change resilience, resource conservation, and waste management.
The first necessary step is studying the local environment (microclimate, solar orientation, prevailing winds) and the urban structure (surrounding buildings forms and uses, nearby sources of noise and air pollution, transport links).
The next step is to take a bioclimatic design approach. This involves deciding on a building shape, the extent of glazing (depending on the orientation), the opportunity for natural ventilation, the type and heaviness of the structure of core and shell and the internal layout. The fabric is critical to a building’s profile, because it creates a balance between indoor and outdoor environments. On one side, it shields the occupants from the outside (heat, cold, air pollution, noise), on the other, it connects them to the outdoors (views, light, fresh air).
The size, positioning and type of windows and glazing control the amount of heat, light and air entering the building. There are numerous ways windows can help create a sustainable building. Transparent areas facing south (the side with most solar exposure) act as passive solar systems, roof openings bring natural light into the core of a building, open windows encourage horizontal (cross) and vertical (stack) ventilation strategies, the height of the windows determine the depth of the natural light penetration into the rooms, and appropriate shading systems such as brise-soleil reduce the heat but still let natural light in.
Waste is another important consideration. You may wonder how you can influence an end-of-life issue when you are still designing a building. By moving from a linear economy (raw materials, use, material waste in landfill) to a more circular economy (reuse of materials from previous cycles, use, responsible disposal that enables reuse or recycling), taking any possible steps to reduce the need for raw materials and also utilising design elements that can be easily deconstructed and recycled, once can impact the end-of-life of a project from the outset.
Using less material in the first place and planning to implement intelligent solutions - such as modular offsite construction - are also effective strategies to lower the amount of building related waste.
And finally - the exciting world of materials and thermal mass! An area that often involves embodied carbon, circular economy and innovation. Appropriate insulation and high performing windows, high levels of recycled content and phase change materials could contribute greatly to the embodied carbon footprint of a building, and affect the operational carbon footprint too! High thermal mass, especially appropriate in areas with hot summers, keeps a more stable and controlled internal temperature without spending additional energy, especially when combined with night time cooling. Please note however, that in some cases high thermal mass could add to the embodied carbon, so careful consideration should be given to the environmental impact of each project and how much operational carbon is saved in comparison.
Concluding this section on features of sustainable design, we would like to make the point that building extends beyond its outline, therefore the design of the outdoor features (parking areas, courtyards, roof terraces, breakout areas) can greatly affect its performance as well as the local microclimate. A clever use of green infrastructure (such as trees, green roofs, green walls etc) and materials can go a long way toward enhancing environmental quality.
It is also important to consider climate change resilience. Two design aspects are particularly important in adapting buildings to climate change: design to avoid overheating and remediation strategies in place for possible flooding events (see images below for design hints).
Key strategies to prevent overheating: 1. Design of site layout with environmental considerations 2. Vegetation 3. External materials with high reflectancy/albedo 4. Airtight and well-insulated buildings 5. Solar shading without compromising daylighting 6. High ceilings and shallow plan buildings 7. Exposed thermal mass 8. Good cross-ventilation
Credit image and text: Sofie Pelsmakers, The Environmental Design Pocketbook, RIBA Publishing