After several starts and stops San Francisco’s greenest office building is finally well on its way to completion. The San Francisco Public Utility District commissioned the project more than ten years ago, but after the dotcom bust and the squeeze of the recession they asked KMD Architects to go back to the drawing board. What they came up with is a reduced cost LEED Platinum building that performs better. With an effective double curtain wall, energy and water efficiency measures, a living machine, a large roof-mounted solar array and integrated wind power the building is projected to cut 60% of its energy needs.
The start-then-stop history of the project turned out to be a blessing in disguise. The building was originally designed to be a typical office next to city hall, however after the first halt in construction Mayor Gavin Newsom asked for a greener project. KMD came up with a fresh design that features a roof-mounted 200 kW solar array in addition to small VAWT wind turbines set on the side and roof.
More budget-saving efforts had the design team value engineer the structure, eliminating steel cross bracing in favor of concrete cores and floor slabs. 70% of the cement is replaced with alternatives like slag and fly ash – both of which are industrial waste products that cuts the concrete’s carbon footprint by half. The new design maximizes the under-floor cooling system to allow the thermal mass to absorb heat in the day and flush it out at night. The redesign also allows for an extra floor to be added.
The double-glazed curtain wall has integrated sun shelves and operable windows to enhance the working environment for the 900 employees. Water-saving strategies were also carefully considered – a living machine placed in the lobby cleans and reclaims waste water, which is intended to be reused for irrigation.
The building is meant to last – not just by surviving monster earthquakes – but by being “self-healing” so that it can be occupied immediately after a large event. Energy costs savings are also a big part of the life cycle of the design – it is projected to save $118 million in reduced costs over 75 years. Add in the increase in employee retention and productivity, and what was once a project that broke the bank is turning out to be a tremendous value for the city.