WindowMaster and Harvard University showcase sustainable retrofitting with automated natural ventilation

The Harvard Center for Green Buildings and Cities (CGBC) is currently retrofitting its headquarters, HouseZero, into a zero-energy building with help from Scandinavian ‘green’ companies. When the building is completed at the end of the first quarter in 2018, it will serve as physical proof that old buildings in the U.S. can be 100% naturally ventilated and fully sustainable.

Together with the architectural firms, Snøhetta (Norway), Skanska Technology (Norway) and Skanska (USA), WindowMaster has designed and supplied the natural ventilation system for the new headquarters. The system uses natural forces, including wind and thermal buoyancy, to regulate the building’s indoor climate based on factors such as humidity, temperature, outdoor weather conditions and indoor CO2 level. This provides a sustainable approach to ventilation with a high level of indoor comfort for the occupants.

With this retrofit project, CGBC aims to demonstrate how older buildings can live up to the ever-increasing energy efficiency demands. Up until now, most of the building projects that have focused on achieving zero-energy are new buildings. And while numerous new buildings have achieved net-zero or positive-energy high performance goals, the retrofit potential of the current U.S. building stock has not been thoroughly explored. Therefore, the CGBC wanted to inspire others by providing an example of how old and conservative buildings can be altered with the right technologies and design to create an ultra-efficient facility with ambitious performance targets. One of the means with which HouseZero aims to reach the target is by using a natural ventilation design strategy.

Designing with natural resources
HouseZero is originally a 1940s-residential building situated on Harvard University’s campus in Massachusetts. The building will house research dealing with global climate change and sustainable building design strategies. It will consist of the old, original wood structure, a solar chimney and a subterranean extension to the existing building called the vault. The current conventional heating and cooling systems in the house (including gas-powered boiler, hot water heater, steam driven radiators, forced-air ventilation and window-mounted air conditioning units) will be fully replaced with the addition of thermal mass, including radiant surfaces, as well as automated natural ventilation inside both the existing house and the vault. Rather than approaching the project as a hermetically-controlled box, the envelope and materials of HouseZero are designed to interact with the seasons and exterior environment in a more natural way. Much like a layered approach to clothing, the house is meant to adjust seasonally.

All glazing systems in the house are replaced with triple-glazed, low-E windows and skylights, which are fully motorized through WindowMaster’s automated system. The control system will allow the building to fully monitor the temperature, humidity and air quality through internal and external sensors. Manual overrides of the automated system are also incorporated.

The zero-energy natural ventilation strategy is attuned to seasonal and climatic variables through adaptive installations, some passive and some with algorithm-based control technologies. Ventilation is controlled via WindowMaster’s actuated windows on all floors, while a passive solar chimney contributes to critical ventilation of the vault and the event space in the basement. Operable skylights are added to the roof plane to allow for a robust ventilation of level 2 and 3 as well as the stairwell.

Targeting the most rigorous efficiency standards ever attained by a building retrofit in the U.S., the project will achieve groundbreaking reductions in energy consumption and carbon footprints. This in turn will be visible
on the electricity bill, where the high cost for A/C and mechanical ventilation will no longer apply.

A sustainable future
The overall design of HouseZero is driven by highly ambitious performance targets, including 100% natural ventilation, 100% daylight autonomy, near-zero energy required for heating and cooling, and zero carbon emissions.

Sustainability remains a major topic within the design profession but in terms of the environmental impacts from buildings there is still a long way to go. As a first-of-its-kind research project, HouseZero demonstrates how to transform a challenging, old building into a prototype for ultra-efficiency, reducing the reliance on energy-intensive technology while simultaneously increasing well-being of the occupants and creating a comfortable indoor environment.

WindowMaster is an expert in sustainable building with automated natural ventilation, mixed-mode ventilation and intelligent building control including solar shading, heating and cooling. For the past 30 years they have designed and installed countless sustainable natural ventilation projects in new buildings as well as retrofit projects. It is at the core of their business to promote and improve sustainable ventilation techniques and to continuously develop enhanced solutions based on research.

Besides HouseZero, WindowMaster has been involved in projects like the PNC Tower and the Bullitt Center in Seattle along with small and large-scale projects world-wide.

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Nanna Birkedal, PR & Marketing Project Manager, WindowMaster