CREJ - Building Dialogue - September 2015
In any building project, there are a number of choices to make. One of the most critical decisions is how the building will source and use energy. With an increase in sustainability practices, -- alternative energy systems are being given greater consideration. Project economics, installation capabilities and design are all factors in determining the most optimal solution. One of the greatest assets a building partner can bring is the ability to provide a variety of options for renewable energy integration and energy conservation. Our firm designed the recently completed Gilpin project, located in a dense residential neighborhood in Denver, which presents a case study in selecting an integrated, 100 percent renewable energy system. In this case, geothermal and solar energy were selected to supply the full energy source. Solar panels installed on the south-facing roof captures power to charge internal heat pumps, artificial lighting and plug loads. As a complementary system, geothermal energy most efficiently heats and cools a large volume of space. Comparing the cost and installation of solar photovoltaic and geothermal, these two systems vary widely. In the case of Gilpin, 20 kWh solar panels cost the client (after rebates and federal tax credits) approximately half of what the geothermal system cost, which requires a trained installation team. Additional considerations associated with geothermal installation include: drilling the wells, compression, monitoring computer and in-floor distribution. There is a common misconception that geothermal is not accessible because of the drilling rig height requirements. However, there are many instances where creative problem solving and integrated energy planning can open greater possibilities to geothermal. On the Gilpin project, a central atrium was planned ahead of time to increase passive solar energy and make a connection to the outdoors from inside. Since the atrium required a hole to be cut in the ceiling, this made it possible to use a compact rig to drill the wells. In order to ensure 100 percent renewable energy reliance, the gas line for the Gilpin project was cut off at the source. Without gas available, there is a clear demonstration of the building’s energy efficiency. Each month, the utility bill reveals a simple view of the energy generated and consumed. Taken together, these systems will generate more energy than the building consumes. The result is an E-positive situation, which supplies surplus resources directly to the power grid for cost savings and a monthly rebate. While the renewable energy system is the core of the building’s efficiency profile, energy conservation measures further enhance energy and cost savings. Starting with an existing structure (lowering the amount of energy required to construct the building), high-density foam was used to seal the flooring and places where thermal heat loss is known to occur. A vampire switch that reduces the building’s power to its most basic need when no one is there was installed to conserve energy at night. Energy-efficient windows were installed throughout and passive solar energy occurs through the central atrium. One of the main benefits for larger citywide energy savings is that at times when Gilpin is adding electricity to the power grid, by powering immediate neighboring electrical loads, this reduces the need for electricity to travel long distances across the grid and conserves greater resources. The Gilpin project demonstrates myriad ways renewable energy can be integrated and implemented with intention. While each project inherently possesses different specifics and economics, there typically are several opportunities to incorporate renewable energy or energy conservation. The best way to find out is to talk with your next building partner.