Sustainability

College Heights seeks to achieve sustainability on multiple fronts. These fronts include sustainably sourced eco- and human-friendly construction materials and methods; side-by-side row house construction for conservation of materials; energy-efficient appliances, fixtures, heating and air conditioning for maximum comfort while maintaining sustainability.

Construction

Green Building Materials

  • Sustainably sourced lumber (certified by the Forest Stewardship Council or similar reputable certifier)
  • Health- and Eco-friendly paints and finishes
  • Low waste, high efficiency building techniques and materials
  • Rain screen siding which discourages mold

Air: Local and Global

  • Global warming: Reduced fossil fuel use, less greenhouse gas production
  • Lowered dependency on oil
  • Reduced uncertainty from rising fossil fuel costs
  • Reduced use of cars that use fossil fuels
  • Less air pollution from lower neighborhood traffic and congestion

Water

  • Water efficiency: fixtures, reduced inside and outside water use
  • Rainwater barrels for roof run-off collection for landscape use
  • Rainwater retention using large trickle-out pipes under walkways; zero runoff
  • Absorption on-site of rainwater and grey water for irrigation
  • Landscaping using drought tolerant, native plants, reducing irrigation needs
  • Less water pollution from oil drippage and other auto related pollution

Grasscrete for permeability

Land

  • More efficient use of land saves farmland and wildlife habitat
  • Housing clusters reduce walls and overall footprint
  • Conservation of the Crevice Creek riparian zone

Energy

Passive and Active Energy

The combination of passive energy and active thermal and photovoltaic energy support no net electricity from 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

Passive energy is built in during design and construction. Three story row housing optimizes building energy conservation, using 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 can create an 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.

Active Energy

The solar active energy system is sold separately from housing, reducing housing cost. It is paid for at time of purchase by direct purchase or by a lease. The cost below a typical PG&E bill. Separate solar 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 on the backside from bounced sunshine. Pumps and a system of pipes connect the hot water from the modules to large heat pumps on the roof tops of the units. Hydronic heaters and heat exchange means there is no duct work, heating and cooling comes directly through pipes built into the unit.

In each unit are small domestic hot tanks boosting hot water temperature 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 storage heats units using hydronic air conditioners in units. Central thermal storage cools water 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 storage for use in winter.

Active Energy: Electrical

Bifacial PV modules are mounted on racks to allow light bounced from roof 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 per watt cost of $2.97 for smaller projects, around $2.20 with tax incentives.

The units will have LED lighting with occupancy sensors to turn lights on and off. Smart Thermostats with occupancy sensors can be programmed to adjust indoor 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 appliances, computers, and entertainment electronics are to be 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 units. 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.