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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 52-55 without the PV
system considered, and a HERS rating of 36-39 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)
460622343Villa TriesteRomaNVLas VegasNV
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.
460622343Villa TriesteRomaNVLas VegasNV
Design Details
Center for Energy Research
at UNLV
The size of these arrays – manufactured by Sun Power Corporation – is rated at 1.764 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.
2343Villa Trieste82109Las VegasNV
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.
2343Villa Trieste82109Las VegasNV
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 204-210.
R. Boehm, Minimizing Peak Residential Electrical Demand in Hot Climates, 2nd 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. 689-697.
R. Boehm, An Approach to Decreasing Peak Electrical Demand in Residences, 2nd 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. 2925-2931.
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. 3617-
3631.
Suresh B. Sadineni, Fady Attallah, Robert F. Boehm, Measurements and Simulations of Electric Demand
from Residential Buildings for Peak Load Reduction, ASME 5th 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 website www.pulte.com
NV Energy home page www.nvenergy.com
U.S. Department of Energy
Office of Electricity Delivery and
Energy Reliability
http://energy.gov/oe/office-electricity-
delivery-and-energy-reliability
Sun Power Corporation http://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 454027
Las Vegas, NV 89154-4027
Phone: (702) 895-0429
Fax: (702) 895-1123
Director:
Robert F. Boehm, Ph.D., P.E.
Phone: (702) 895-4160
Email: [email protected]
Co-Directors:
Yahia Baghzouz, Ph.D., P.E.
Phone: (702) 895-0087
Email: [email protected]
Yitung Chen, Ph.D.
Phone: (702) 895-1202
Email: [email protected]
2343Villa Trieste82109Las VegasNV
