Greening San Francisco's Old Mint

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As a piece of architecture, Alfred Mullet's 1874 classicaly-inspired building is a beaut. It's one of the last best examples of the wave of neo-classicism that swept the nation in the 19th century, and a building that at one time held a third of the US's gold reserves. Not only did it escape largely unscathed during the devastating 1906 earthquake (how rarely surviving catastrophe is suggested as a "sustainable" element of a building), but the team working on the building now aims to put it at the vanguard of green design.

By reopening windows that were long sealed, and embracing the courtyard as a natural lung for the building, the Old Mint can return to the very progressive natural ventilation system that Mullet devised back in 1874.

I chatted with Paul Woolford, lead architect on the project and design director of HOK San Francisco about what he and his team aim to do at the Old Mint, and how preserving the buidling itself, letting it do what it was designed to, ends up looking like the greenest stragegy of all.

This rendering shows how Alfred Mullet's building--he also did the executive building next to the White House--will look when the renovation is complete. At present San Francisco is one of only two major cities without a museum dedicated to its history. Staggeringly, history-obsessed Boston is the other.

Click here to view a slideshow of the building itself as well as HOK's plans for greening the Granite Lady, or check out this very fine story from SF Chronicle architecture critic and Dwell-contributor John King on the buidling.

Here's a picture of the Old Mint from 1889. It still stands at the corner of Mission St. and Fifth St. in large part thanks to it's foundation, which rests of loose gravel and soil, allowing the building to roll and shift during the 1906 earthquake instead of cracking and splitting apart.

How do you plan to both honor the Old Mint as a great San Francisco building and still put it to work as a modern museum?

Here's a view of the Old Mint today. You can see the San Francisco Chronicle building to the south (just across Mission St.) and to the north is a recently-renovated outdoor space called Mint Plaza. An interior courtyard in the Old Mint will be open to the public free of cost, and serve as an internal lung for the building's ventilation system.

In the Mint Project, the client and design team realized that we had the opportunity to create the most environmentally innovative National Historic Landmark in the US. From the day we began the project, we approached the original Alfred Mullet building as if it is the most significant artifact in the Museum’s collection. Every design decision took its cue from this idea.

This diagram shows how the Old Mint will capture rainwater through a canopy system that funnels run-off into a drainage system that can be treated and stored onsite. A green roof will use up some of the water, but other functions, such as use in the plumbing system, will help ease reliance on city water.

During the tour you spoke about how the building is already surprisingly sustainable already. What steps are you taking to bring what was utterly admirable design from the late 19th century up to 21st century standards?

The building is already quite advanced in terms of passive ventilation and temperature control, but by dividing it into various occupational zones, and permitting localized climactic zones, the building can address particular heating and cooling needs without taking the whole of the structure along with it.

When we looked deeply into the problem, we found that the answers were often already in front of us. The real challenge wasn’t to cover them up with so called modern day mechanical and electrical solutions, but to express and build upon the design opportunities already inherent in Alfred Mullet’s original design. Every time we have made a sustainable intervention, we have orchestrated them so that a single move achieves multiple solutions. For example, while the roof canopy over the court protects the historic stone courtyard below, it also “floats” above the parapet to respect the original details and allows for natural ventilation of the building. It brings day light deep into the building, and it will have photo voltaic cells embedded into the glazing which will generate energy and serve as a filter for the daylight.

The central courtyard in the building was designed to allow daylight to penetrate to the ground floors of the building. In 1914 a new floor was built higher up, cutting off the bottom floors from daylight. Modifying that addition will permit Mullet's ideas to come back into play.

Have you found strategies that allow you to work simultaneously as a preservationist and a green architect?We’ll restore the historical operable windows, and they will become an integral part of the passive ventilation system. But rather than just opening a window, as was done in the 19th century, these windows be the outer layer of a “super trickle vent”. They’ll have a parallel pane of glass behind them to filter the wind, there will be sound baffles at the top and bottom of the opening to muffle any street noises, there will be screening to prevent intrusion from pests and birds, and there will be a light refraction embedded into the internal pane of glass to bounce light onto the ceilings of the interior spaces, thereby reducing the demand for artificial lighting.Surely some elements of the building will have to be redone? Many of the floors within the building are in ruin, so new floors will “float” above them. These raised floors will provide a walking and display surface for the galleries, radiant heating (from hydronic tubing below the floor), and a means for data and electrical distribution without cutting up walls and ceilings.We're looking at this building as a palimpsest, and right now we're writing a story atop what's already here so that we can preserve it for future generations.

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