Eco-Home at Hawk Ridge
Model Solar House
Now for sale $425,000
Call 218.733.1451 for a tour...
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Printable Eco-Home Documents:
Eco-Home at Hawk Ridge is a Model Solar Home demonstrating energy
efficiency, renewable energy and green building.
Location: 2809 Snowy Owl Circle Duluth MN 55804
Groundbreaking: September 14, 2006.
Opening: May 12, 2007, (Open House Thurs June 21 from 6-9)
Builder: Women in Construction
Company LLC
Architect: Wagner Zaun
Architecture
Energy Systems Consultant: Conservation Technologies
Anatomy of an Eco-Home Photo Gallery
Features of the Eco-Home Design and Construction Methods
This project has been a joint effort between Women
in Construction LLC and several other local
and state agencies. The home will initially be used for demonstration
and educational purposes, and the design and construction methods will serve
as an example of how to build low-energy, high performance homes with attention
to conservation and health of people and the environment. The overall concept
features site-sensitive passive solar design with grid-tied solar PV array,
solar domestic hot water system, solar hybrid heating design, and high-performance
thermal envelope.
- 2,000 square feet of living space with a semi-attached garage
- solar-oriented
siting and space planning
- envelope R-values for walls, roof, and under
slab insulation are nearly twice what code requires
- double stud exterior
walls with R-36 cellulose insulation
- cellulose attic insulation levels
of R-60
- frost protected slab foundation with underslab insulation R-20
- rim insulation
R-23
- triple pane fiberglass windows (U-0.19)
- assembly details for superior
air tightness
- radon mitigation system
- 2 kW roof-mounted solar photovoltaic array
- 16-tube solar thermal collector
for domestic hot water
- Energy Star appliances and lighting
- Detailed energy analysis using REM
Design modeling software
The high-performance envelope design and detailing resulted in a design
heating load of less than 18,000 Btu/hr, or about 8 Btu/sf.
This very low heating requirement led to a heating system design responding
to the low-energy goals of the home.
About the Solar Demonstration Home Heating System Design
The
house has a "hybrid" design, where a combined system provides
both heat and domestic hot water. It is a combination of very current
technologies, high energy efficiencies, and renewable energy. The concept
of "hybrid
technology," using the on-demand water heater coupled with a solar
domestic hot water system, makes this model worthy of
the title "demonstration home." It is a reliable whole house system,
without a boiler or furnace.
The tank from a roof-mounted solar thermal collection system acts as a
preheat/storage plant for domestic hot water. At times, in summer, the solar
thermal system will be providing all of the house's domestic hot water.
The output from the hot water tank runs through an on-demand water heater,
which acts as a boost when the system needs a rise in temperature. A loop
off of that on-demand heater runs through a heat exchanger and returns to
the tank. The secondary side of the heat exchanger is the distribution system
for space heating. The first floor slab is heated with radiant tubing, as
is the second floor bathroom. The remainder of the second floor receives
warm air via the ventilation system.
A small wood stove in the living room provides additional space heating
for the open areas of the first floor. The addition of space heat on
the first floor provides a “quick heat” option when occupants
want a faster response time than the radiant floor typically provides. The
wood stove alone is capable of heating the entire house.
The Domestic Hot Water / Heating Plant
An 85-gallon water storage tank, heated by a roof-mounted solar thermal
array, is assisted by an on-demand hot water heater (natural gas) as needed.
The on-demand water heater thermostat is set to approx. 120 degrees F.
When the system calls for hot water (either domestic or as heat), the
water leaves the storage tank and runs through the on-demand heater. If
the water is not as hot as the set temperature, the heater fires to “boost” the
outgoing water to the required temperature. If the water in the tank is
hot enough, the water heater is not activated and the water flows on through
the distribution system.
The Distribution System
If the call is for heat, delivery begins as described above, but after
passing through the on-demand heater, the water runs through a closed
loop with a heat exchanger. There are two zones, each with a different distribution
system.
Zone 1- in-floor hydronic radiant heat. Runs throughout the first floor
slab, and also in the second floor bathroom. The second floor bathroom
heat is controlled with a manual balancing valve, so that its temperature
can be adjusted relative to the first floor heat.
Zone 2 – warm air distribution to the second floor bedrooms and
study.
Warm air is heated with a heat exchanger and circulated via the ventilation
system.
System Design and specifications prepared jointly by Wagner
Zaun Architecture and Conservation Technologies
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