When UK-based architecture firm Stride Treglown sat down to design their own office, they took on the challenge of creating the most sustainable building they could afford. The result is the earliest pre-emptive BREEAM Outstanding award conferred for any building. The prefabricated building features an efficient envelope that encourages a well-balanced synthesis of natural light and ventilation. A biomass boiler, green roof and solar panels help propel the design into the elite class of buildings that consume net zero energy.
When the firm first began to design their new office they were determined to maximize the building’s efficiency with the ultimate goal of zero net energy. Rather than relying on a lot of solar panels, the design utilizes a host of energy efficiency measures. The prefabricated wall system is based on a wooden timber cassette frame that provides deep pockets filled with cellulose insulation.
The green roof was designed to add thermal mass to regulate temperatures, and in the summer it helps cool the building. Carefully designed internal spaces can be naturally cooled with cross ventilation and night flush cooling. The same projection of the building’s roof that induces draft also acts as a light scoop, reflecting diffuse daylight into the offices. Southern windows are kept small, but the northern street-side windows are enlarged to provide more light without heat gain.
In order to meet net-zero energy, the small solar array on the top of the building will need to be enlarged — an interesting compromise, as some of the green roof will need to be removed. The building is heated with a biomass boiler located in the basement that feeds an in-floor heating system. Even sink water is reused for the toilets with a point-of-use greywater reclamation system.
All of this adds up to a 55% reduction in carbon emissions from code (yes, they even have a building code for that). The BREEAM Outstanding certificate was awarded even before 90% of the design phase was complete and is the highest level attainable by the green building system. The certification can be revisited after full occupation of the building.
WHY THIS MATTERS
High-performance buildings need to have a clear strategy at the beginning of the design phase in order to be successful. Stride Treglown’s success stems from the way they developed a fully integrated design by committing to energy performance from the start — they only added renewable energy when the design accounted for energy consumption.