Integrating Design Elements with ResourceEfficiency
In designing the changes to, and expansion of, our existing house, we wanted to make it as ‘green’ as possible. Our goal is to be certified LEED Platinum. Whenever possible, we are incorporating energy efficiencies with the remodel and new construction design, which will serve to reduce the adverse impact on the environment and lower the ongoing operating costs of the house.
A major functional change that will enhance the energy efficiency of the house is to cover the atrium and surround it on all sides with clerestory windows. With calculated overhangs, this passive solar design will cascade natural light through the atrium into the lower level, reducing lighting requirements while avoiding solar heat gain in the summer.
The new roof will be made of structural insulated panels (SIPs) and the floor composition will include hollow core concrete panels. Both SIPs and hollow core concrete panels are manufactured offsite to the exact specifications required, which reduces the construction debris and accelerates the timeline to complete the project. The SIPs, rated at R-45, will make the house more airtight and increase the insulation value, resulting in reduced heating and cooling requirements.
As with the existing house, a white membrane roof will help to reduce the heating requirements and also integrate with a rainwater harvesting system.
There will be 32 photovoltaic solar panels on the roof that will generate electricity for a net zero energy demand. Covering the atrium will increase the area available for additional solar panels, which can be added at a later date. The installation infrastructure, brackets and wiring, and inverted will be in place, making it fast and easy to add an additional 16 photovoltaic panels.
The original 2×6 tongue and groove Redwood roof decking and 4x Douglas Fir beams in the center of the house will be removed carefully so the lumber can be remilled. The Redwood decking will be sawn in half and have a new tongue and groove, exposing the gorgeous wood grain of this classic California timber while doubling the volume of wood available. The remilled wood will be placed under the SIPs and hollow core concrete panels, creating a beautiful ceiling throughout the house while reducing the remodeling and new construction debris, also reducing the corresponding need for new materials.
The landscaping will include native northern California species that will be irrigated with the rainwater harvesting system.
Adding the lower level will require drilling and installing concrete piers just outside the perimeter of the house on the east and west sides. A geothermal ground loop will be placed in these 25 concrete piers that will enable heat exchange to both heat and cool the house. The geothermal heat exchange will compliment the photovoltaic solar panels on the roof, reducing the total external energy load.
The entire structure was calculated to be 72.9% more energy efficient than California’s Title 24 requirements, so it is extremely energy efficient.