The Harvard Center for Green Buildings and Cities (CGBC) at the Harvard Graduate School of Design (GSD) announced the completion of HouseZero, the retrofitting of CGBC headquarters in a pre-1940s building in Cambridge, Massachusetts, USA, into an ambitious living-laboratory and an energy-positive prototype for ultra-efficiency.
Thanks to 285 sensors embedded within it, collecting almost 17 million data points each day, the building will adjust itself seasonally, and even daily, to reach thermal comfort targets for its occupants. This data infrastructure enables the building to immediately respond to both external and internal variables such as outdoor air temperature or rain, and indoor CO2 levels and air temperature.
An open floor plan and careful selection of lighter-coloured materials enhance the sense of openness in the space. Additionally, the design emphasises the acoustics of the existing structure, from exposure of the existing beams to creation of double height spaces, to elevate the spatial experience and occupant comfort.
At the centre of the building, a faceted stairwell spirals up through all four floors, reducing disturbance from circulation. As part of a unique digital exchange, the hexagonal panels of the stairwell have been robot-milled and finished by students at the Harvard Graduate School of Design.
A solar vent at the East façade is used to instigate buoyancy-driven natural ventilation throughout the interior, while its glazed sections allow natural light to enter the stairwell. Sculpted window shrouds protect the interior, maximising daylight use and passive solar practices in each space.
Beyond the retained existing materials, new, locally available materials of high performance, such as locally-sourced white cedar shingles, ash and birch interior finishes, ultra high-slag concrete, natural clay plaster, and reclaimed brick and granite, create a balanced indoor climate.
A collaboration with energy engineers Skanska Teknikk Norway, HouseZero’s performance targets include nearly zero energy for heating and cooling, zero electric lighting during the day, operating with 100% natural ventilation, and producing zero carbon emissions. The sustainable building is intended to produce more energy over its lifetime (over a 60 year life span) than was used to renovate it and throughout its subsequent operation, and will be accessible to the public through tours and live demonstrations of its technology.