- Sustainable lumber (certified by the Forest Stewardship Council or similar certifier)
- Healthy paints and finishes
- New low waste, high efficiency building techniques and materials
- Rain screen siding against mold
- Global warming: Reduced fossil fuel use, less greenhouse gas
- Less dependency on oil and imports
- Reduced risks from rising fossil fuel costs
- Reduced use of cars that use fossil fuels
- Less air pollution from less traffic and congestion
- Water efficiency: water-efficient fixtures, reduced water use and sewage
- Rainwater barrels for roofs
- Rainwater retention using large trickle-out pipes under walkways; zero runoff
- Absorption on-site of rainwater and grey water for irrigation
- Landscaping uses drought tolerant, native plants, reducing irrigation needs
- Less water pollution
Grasscrete for permeability
- More efficient use of land saves farmland and habitat
- Conservation of the Crevice Creek riparian zone
Passive and Active Energy
The combination of passive energy and active thermal and photovoltaic energy support no net electricity off the grid over the course of a year–“net zero”–with electrical use in winter balanced by electrical generation in summer. Solar energy provides all domestic hot water, air conditioning, air cleaning, air renewal, and electricity for cooking, appliances, lighting, plugs, and electronics
Passive energy is built into the house. Three story row housing optimizes building energy conservation, 2”x6” studs, not 2”x4”, creates space for more insulation in walls. The project may also use Structurally Insulated Panels (SIPs), which provide greater energy efficiency than standard “stick building.” SIPs are from 30% to 60% more efficient. A 6″ SIPs wall has an R-Value of 21.6 while a 6″ stud wall has an R-Value of 13.7.
Doors and windows are energy conserving. Well-constructed “tight buildings” are tested by blower doors. R-26 insulation for walls and R-50 for ceiling exceeds California Title 24 energy regulations.
Tight construction creates air quality problem of mold and bacteria from stagnant air. Air exchangers with air filters and whole house fans keep the air circulating to maintain indoor air quality, continuously refreshing the air when windows are closed.
Reflective exterior building materials and double-glazed, reflective windows make efficient use of the sun’s energy, shielding from heat in the summer and maximizing light in the winter. Skylights and clerestories with exterior sunshades, awnings and sun shades provide natural light to interiors and avoid bright/dark interior lighting contrast caused by direct sun.
The active energy system is sold separately from housing, reducing housing cost. It is paid for at by direct purchase or over time by a lease. The cost below a typical PG&E bill. Separate energy financing makes the mortgage on the unit more affordable. Qualification for the mortgage would increase if the lenders give credit for reduced transportation costs (the transportation efficient mortgage), and for improved proximity to destinations (the location efficient mortgage).
Active Energy: Thermal
Solar thermal energy provides domestic hot water and space heating. Photo-voltaic Thermal (PVT) modules installed on sloped roofs generate electricity topside and heat backside from bounced sunshine. Pumps and a system of pipes connect the hot water from the modules to large heat pumps in a central thermal plant, large thermal water storage and the units. The central thermal plant is efficient because of the size of the project. Large heat pumps in the plant heat or cool water as needed. Thermal energy is stored in central thermal storage, a large underground borehole, A four-pipe distribution system connects the modules to the central plant, the central storage, and the units.
In each unit are small domestic hot tanks boosting hot water temperature from the central thermal storage as needed. The units also have unit hydronic air conditioners/space heaters with a small “fan coil” for space heating and cooling using a fan blowing across pipes with fins, and hydronically warmed towel racks which dry towels and heat bathrooms.
Winter Summer Thermal Balance:
Winter: Hot water from central storage heats units using hydronic air conditioners in units. Central thermal storage cools down.
Summer: cool water from thermal storage cools units and the PV thermal modules for highly efficient production of electricity from a cooler module. Electricity and hot water from PV thermal modules and heat pumps recharge the central storage for use in winter.
Active Energy: Electrical
Bifacial PV modules are mounted on racks to allow bounce light to reach PV on the backside. Large scale construction of advanced technology PV panels makes PV electricity very efficient. The cost of electricity is estimated at $1.89 per watt, well below the cost for smaller projects, which is $2.97, $2.20 even with tax incentives.
The units have LED lighting with occupancy sensors to turn lights on and off. They have Smart Thermostats with occupancy sensors to adjust the temperature before people get home. They have induction cooktops, which are faster, safer, more energy efficient, and less polluting than natural gas or electrical resistance. High efficiency Energy Star appliances, computers, and entertainment electronics are used exclusively: refrigerator, range, dishwasher, microwave oven, front-load clothes washers and dryers.
Active Energy: Designing and managing
The HOA assets get the same attention as the nits. Walkway lights and fountains are solar powered. And, water conservation means less pumping of water, again saving electricity. Computer modeling using a Balanced Design Approach optimizes all parts of the system for net-zero and life cycle cost-effectiveness. HOA management operates the system using continuous commissioning for increased productivity. The HOA helps residents manage their systems. Submeters in each unit report use, helping residents monitor and manage energy use.