August 17th, 2009

Zero Energy Home in San Francisco

Posted by Bridgette Meinhold

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Homes of the future will go beyond including green design elements, low VOC paints, and solar systems. Homes of the future will be carbon neutral, generate all their own power, some of their own food and have integrated systems to increase energy efficiency, reduce water consumption and minimize waste. Plans for the first Zero Energy House in San Francisco are underway, and this house will be a model of efficiency and green design to other homes in the area. Not only is the Zero Energy House by LSarc carbon neutral, but it includes a solar system on the roof and many integrated systems to make for one very sustainable house.

The home itself is a new construction, but placed within a historical setting. The home will allude to the surrounding architecture, but will update to a more contemporary style with more open and functional space. The bedrooms and rooms will be placed at the front of the house closer to the street, while the open living spaces like the kitchen and living room are placed at the rear and south side of the building.  An open floor plan make the common areas feel open, and large south-facing windows provide more warmth and natural daylight.

To be built on a traditional narrow lot in the city of San Francisco, the Zero Energy House aims to be the first home that is self-powering and carbon neutral. The owner, who has been working in the solar industry for over twenty years, says he is committed to, ‘getting off the pipe, a house without a gas meter.” Careful consideration has been given to integrated systems to increase energy efficiency. The house has three main systems which operate to make for an incredibly sustainable house: the Water Recycling System, Radiant Heating System, and the Electric System.

Water Recycling System

To minimize water consumption the Zero Energy House includes both graywater recycling and rainwater harvesting systems. Graywater is collected from sinks, showers and tubs and stored in a 1,500 gallon storage tank on the bottom floor. This graywater is then used for irrigation in the backyard vegetable garden as well as the drought tolerant landscaping in the backyard and on the street. The rainwater harvesting system collects water from the backyard drainage and stores it with the graywater. The backyard edible garden is actually shared with the next door neighbors and should provide a good portion of the families’ food.

Radiant Heating System

The home is heated with radiant heating system in the flooring. Radiant heat tubes snake all throughout the home on every floor to provide comfortable and efficient heating. Each floor acts as a passive solar collector on the south side of the house and passes heat through the tubes to the rooms on the north side of the house. A 2/3 ton, electric heat pump on the roof provides hot water for the floor system, while a second heat pump on the bottom floor provides domestic hot water. A three story stair well is located in the center of the home, and at the top of the stair well are operable skylights. When the skylights are open, the stair well acts as a ventilation tube and hot air is released out through the roof for natural ventilation and cooling. Both the radiant heating and natural cooling are coupled with high efficiency windows, R-19 walls and an R-40 roof insulated with Biobase soy foam insulation for a tight house.

Electric System
Super efficient LED lighting and appliances help to minimize the electric load for the house, which is supplied by an 8 kW solar photovoltaic system is place on the roof in order to generate all the power needed by the home. The house is oriented North-South, and the solar panels are angled half to the east and half to the west to maximize energy production in the morning and evening. The pv system will also generate power for an electric plug in vehicle recharged on site in the garage. This solar powered system will allow the how to remain carbon neutral.

+ LSarc

via Green Architecture Notes

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