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Passive Solar and Ecological Features of the
Real Goods Retail Showroom
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To design the Retail Showroom at the Real Goods Solar Living Center, the team conducted a careful analysis of the climatic conditions of the inland valley site in northern California. Several tools helped respond to the climatic conditions of the site and aided and informed the design work.
Solar Gain Analysis And Control
Heliodon studies were performed at the Pacific Energy Center in San Francisco. The Heliodon table helped to quickly simulate solar azimuths and angles throughout the day and year. A video camera equipped with a fiber optic lens placed inside the model films direct sun penetration throughout the day. This ?time-lapse? video proved an invaluable tool for study as well as an effective means of presenting the concept to the Real Goods staff, effectively bringing the building to life during the design process.
This analysis provided the information needed to shape and size the southern overhangs, sunshades, and awnings. The building welcomes solar gain in the winter and spring but keeps it out in the summer and fall. Employees can tune the moveable awnings to seasonal variations and can fold insulated translucent interior light shelves against the low-e glazing on winter nights to greatly reduce heat loss.
The straw bale walls, 23 inches wide with 3-to-4 inches of PISE? gun-earth on each side provide an R-value of 65 as well as significant thermal mass. These walls, in combination with the thermal mass in the floor and columns, moderate outdoor temperature swings throughout the day and year. Consultants, including the Pacific Energy Center, have all concluded that ?you can?t have too much mass? (so long as it?s within the insulation envelope – especially in more severe climates).
An ?Operator?s Manual? has been provided to the Real Goods store staff to teach them how to properly tune the building for comfort, i.e. when to open or close the clerestories, etc. This could have all been automated, but Real Goods chose to let the staff interact with the building to afford them the opportunity to learn about their environment.
Daylight As Form-Giver
The curved roof was selected not so much for its relationship to the plan as for its qualities in helping distribute daylight throughout the showroom.
A large-scale section of one of the bays was built and several options were tested for even distribution of daylight in the Sky Dome at the University of California at (UC) Berkeley. Seven Licor photometric sensors wired to a Campbell Scientific datalogger produced daylight factor graphs. Our seventh test, featuring highly reflective film on a tilted shelf, produced the most even distribution of daylight. We are considering mounting reflective scoops above the trellis, on pulleys for adjusting the angle seasonally.
Wind Tunnel Testing
Substantial breezes from the northwest inundate the Hopland Valley daily. Based on the results of tests at the Boundary Layer Wind Tunnel (also at the UC-Berkeley), the Solar Living Center uses celestory windows at the roofs, which step to the east, to ventilate the showroom. A ?Bernoulli? effect creates a pocket of low-pressure that draws warm air from the high ceiling out of the manually operated windows. The building draws fresh air from the shaded north side, and solar-powered evaporative coolers further cool the air on the hottest summer days. The building will be flushed each cool summer night, storing 'coolth' in the floor, walls, and columns.
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