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Active Design
Heat and domestic hot water are powered by rooftop solar panels, and
electrical power is provided by rooftop photovoltaic (solar
electric) panels. The building design is calculated to result in the
complete fulfillment of all heating needs by solar hot water and the
production of more electricity than is actually used. For normal
electrical usage, a surplus of electricity is generated by the
photovoltaic panels and sent to the regional power grid. For states
with “net metering” this will result in a payment from the electric
company rather than a bill. As rates increase, the amount of the
payments from the electric company will increase.
Solar heat is accumulated in several large super-insulated water
tanks underground; a system of sensors monitors the temperature of
the various storage tanks and the output from the rooftop panels;
alternating the incoming hot water between tanks according to their
various temperatures and the temperature of the rooftop output.
This hot water is then used at different temperatures throughout the
house. Low temperature water provides comfortable radiant floor
heat. Medium temperature water serves domestic hot water (DHW)
needs, hot water supply for showers, baths, and sinks, heated by the
sun rather than a conventional water heater. Very hot water provides
heat to the clothes dryer, the dishwasher and possibly other outlets
as well.
The solar heating system's ability to serve the home's hot water
needs is calculated to be more than adequate; the large reserve of
hot water serves to buffer out the cold nights and gloomier days.
Energy calculations are based on two criteria:
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Designed to provide
full space heat and DHW for more than ten consecutive sunless
days in the dead of winter, without any supplementary heat
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With moderate use of
wood stove, burning at 50% capacity for an average of 8 hours
per day, system is designed to provide full space and DHW for
over thirty consecutive sunless days in the dead of winter.
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Equally important is the
photovoltaic (PV) array's ability to provide sufficient power to operate all of
the home's electrical requirements. Keeping the house tied to the
electrical grid has three major benefits:
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At night or on dark
days when the house needs more power than it can generate, it
can draw from the utility grid; |
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The expense and
maintenance of a large bank of batteries is unnecessary; and
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Surplus power
returned to the grid can actually generate income from the
utility company.
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The output of the PV
system is not designed to be SO bountiful as to provide unlimited
electricity - but should be more than enough to run a household
which is set up with some care to its power consumption. The
Randall Millennium Home incorporates energy-efficient features to
minimize electrical power demands:
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High-efficiency
lighting is used throughout. A combination of high-tech compact
florescent and LED lighting provides “designer lighting” in all
spaces. |
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Windows and skylights
are placed to provide excellent daylighting, reducing or
eliminating the need for electrical lighting during daytime
hours. |
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Refrigerator and
freezer are ultra-efficient appliances consuming much less power
than many commercial appliances. |
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Very hot water supply
to dishwasher reduces need for electric heating of wash water
which most dishwashers provide. |
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Solar hot water heats
inlet air to the clothes dryer, instead of electric heat.
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Air conditioning is
provided through ground-source cooling rather than inefficient
and noisy outdoor compressor-driven condensing coil. |
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Fresh air ventilation
is provided year around by energy recovery ventilator (ERV) which
reclaims the energy content of the exhaust air. In the winter,
the ERV preheats incoming ventilation air flow and in summer it
cools and dries incoming air through energy exchange with
exhaust air flow. |
These systems have been
carefully designed to cooperate and coordinate with each other. The
Randall Millennium Home is a smart house; with a flexible and
comprehensive home automation system. The regulation and operation
of the energy-producing systems incorporates sensors to monitor
usage, flow, temperature; monitoring and regulating in real time the
draw and flow of electricity and hot water, and logging for future
analysis all of the data involved.
We want to insure that our houses are able to meet the owners' needs
without relying on any net input from external power; but the
homeowner also must also be responsible about it and aware that
careless or excessive power draw might tip the balance with the
utility company. This why we incorporate sensors and monitoring
equipment to log the actual usage and consumption.
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