Villa Trieste Homes Building Reduced-Energy Homes in the Southwest U.S. Desert Center for Energy Research at UNLV

Reduced Peak Energy Homes (2008 to 2013) Center for Energy Research at UNLV UNLV’s Center for Energy Research (CER) received a very large contract from the U.S. Department of Energy for a housing development in Las Vegas, Nevada, that can be used to study techniques of reducing peak electrical demand. UNLV’s partners in developing these homes are NV Energy and Pulte Homes. Known as the Villa Trieste community of homes, this development involves: o Significant energy conservation in 185 homes and o Photovoltaic units for solar energy on the roofs of these homes. o A system that allows the homeowner to select the degree of energy savings desired while working in harmony with the utility’s need for peak load control. o Application of peak-shifting storage batteries. The goal is to decrease the peak electrical demand by 65% over code-minimum building designs of the same size. These houses have garnered the prestigious LEED Platinum classification.

Design Details Center for Energy Research at UNLV General Information Floor areas of these single-family, two-story houses range from 1487 to 1960 square feet. The buildings are extremely energy-conserving, with a HERS rating of without the PV system considered, and a HERS rating of including the PV system impact. Standard features o A tankless water heater o A dashboard that gives the resident energy consumption/generation information o R-7 exterior doors o 92 AFUE furnace o 100% CFL lighting o 2x4 and 2x6 construction, with 1 inch of EPS and blow-in cellulose (R-13 and R-19 depending upon the stud size) o Windows with a 0.34 U factor and a 0.32 SHGC o A 15-SEER air conditioner o Unvented (semi-conditioned space) attic Roma model, 1487 sqft (Source: Pulte Homes)

Design Details Center for Energy Research at UNLV Solar Energy Each home has photovoltaic (PV) tiles incorporated in an integrated fashion on its roof. This decreases the HERS rating for the Roma model, for example, from 55 to 39. Because of the nature of the development plan for Villa Trieste, all of the houses will have a PV system with a nearly south exposure, nearly west exposure, or nearly east exposure.

Design Details Center for Energy Research at UNLV Energy conservation features Above, the conditioned attic, which allows the HVAC ducts to be in the same temperature as the interior of the house. At right, the difference between batt insulation, used in traditional houses, and blown-in insulation, used in Villa Trieste. Both sides of the stud have the same piping and electrical installations.

Design Details Center for Energy Research at UNLV The size of these arrays – manufactured by Sun Power Corporation – is rated at kW peak output. They are connected to the NV Energy grid in a net metering arrangement. Each kWh sent to the utility is treated as the same economic value as each kWh used from the utility.

Design Details Center for Energy Research at UNLV UNLV’s Intelligent Server provides instantaneous Information on the cost of power from NV Energy to the homeowners. In this way, the homeowners can adjust energy settings on their thermostats and other controls during peak demand hours in order to save energy and money.

Design Details Center for Energy Research at UNLV Communication System, Intelligent Agent, and Load Control An intelligent agent is being developed that is equivalent to a dial that the customer can set to any choice from ‘No modification of energy loads’ to ‘Full modification of energy loads.’ For a ‘Full modification of energy loads’ setting, an arrangement will be developed in advance between the utility and customer, where each event of load shedding that the utility is allowed would have some type of reimbursement associated with it. Included in the events might be: o Control of the home thermostat for predefined periods o The ability to turn off pool pumps, when present o Controlling plug loads Each of these elements would save both the utility and customer money.

Design Details Center for Energy Research at UNLV Communication System, Intelligent Agent, and Load Control An internet communication system has been developed to allow signals to be relayed from the utility to the customer and from the customer to the utility. One of the purposes of this communication link is to transmit power cost information to the customer nearly instantaneously, and to allow the customer to respond to this information. In general, power costs increase during peak demand periods; if the customer knows this information, then action could be taken by the customer to shed load. This active participation in the cost information exchange greatly contributes to reduced energy consumption in the homes. The customer also can opt to set preferences on the Intelligent Agent to have this activated automatically.

Design Details Center for Energy Research at UNLV Communication System, Intelligent Agent, and Load Control By operating on a whole community, the utility strategy will be such that each home is affected for only short periods of time. Staggering the load control throughout the community will result in a net decrease in load at the substation.

Design Details Center for Energy Research at UNLV Battery Energy Storage System A Battery Energy Storage System (BESS), installed in a selected subset of houses, is being evaluated for its effectiveness. The final phase of the project development is the installation and evaluation of several load- shifting batteries. This system will store electrical energy from the grid at night and be ready to shave peak loads during the day. This particular function is the final choice option. If the various other aspects related to energy minimization and load control are unable to furnish the required peak reduction, the batteries will be called upon to assist in making this reduction. (Right) Battery storage unit in a home. At left is an ‘on-demand’ water heater.

Center for Energy Research at UNLV One of the issues in devising strategies for making houses more energy conserving or for decreasing peak electrical loads is to use a computer model of the house performance. This model incorporates mathematical descriptions – a computer code --how well the key parts of the building function, for instance: o If walls impede heat flow or o How much energy is need for the air conditioning unit to cool the house Ambient weather conditions and human choices for energy use are imposed on this model. This chart compares the simulated computer results (red) with actual measurements from a Villa Trieste home for a two-day period in early summer. Testing the System

Center for Energy Research at UNLV Additionally, instrumentation has been temporarily located in the houses for detailed energy flow analyses. This is in addition to the measuring equipment used to furnish data to the dashboard. Testing the System

Related Publications Center for Energy Research at UNLV S. B. Sadineni, F. Atallah, R. F. Boehm, Impact of Roof Integrated PV Orientation on the Residential Electricity Peak Demand, APPLIED ENERGY, Vol. 92, 2012, pp R. Boehm, Minimizing Peak Residential Electrical Demand in Hot Climates, 2 nd Asian-US-European Thermophysics Conference—Thermal Science for Sustainable World, January 3-6, 2012, Hong Kong. S. B. Sadineni, F. Atallah, R. F. Boehm, Measurements and Simulations for Peak Electrical Load Reduction in Cooling Dominated Climate, ENERGY, Vol. 37, 2011, pp R. Boehm, An Approach to Decreasing Peak Electrical Demand in Residences, 2 nd International Conference on Advances in Energy Engineering, 2011, Bangkok, Thailand. S. B. Sadineni, T. France, Robert F. Boehm, Economic Feasibility of Energy Efficiency Measures in Residential Buildings, RENEWABLE ENERGY, 2011, Vol. 36, pp S. B. Sadineni, Srikanth Madala, Robert F. Boehm, Passive Building Energy Savings: A Review of Building Envelope Components, RENEWABLE AND SUSTAINABLE ENERGY REVIEWS, 2011, Vol. 15, pp Suresh B. Sadineni, Fady Attallah, Robert F. Boehm, Measurements and Simulations of Electric Demand from Residential Buildings for Peak Load Reduction, ASME 5 th International Conference on Energy Sustainability, August 7-10, 2011, Washington D.C. T. France, R. Hurt, R. Boehm, and S. Sadineni, Home Energy Conservation in the Las Vegas Valley, Proceedings of the ASME Conference of Energy Sustainability, San Francisco, CA, 2009.

Resources Center for Energy Research at UNLV More details about the Villa Trieste homes can be found at : Pulte Homes websitewww.pulte.com NV Energy home pagewww.nvenergy.com U.S. Department of Energy Office of Electricity Delivery and Energy Reliability delivery-and-energy-reliability Sun Power Corporationhttp://us.sunpowercorp.com/

For More Information Center for Energy Research at UNLV Center for Energy Research at UNLV 100 Taylor Hall University of Las Vegas, Nevada Box Las Vegas, NV Phone: (702) Fax: (702) Director: Robert F. Boehm, Ph.D., P.E. Phone: (702) Co-Directors: Yahia Baghzouz, Ph.D., P.E. Phone: (702) Yitung Chen, Ph.D. Phone: (702)