Page 45 - November 2015 Green Builder Magazine

Exteriors / Roofing / Structure / Insulation / IAQ / Windows / Heating / Lighting / Appliances / Faucets & Fixtures / Finishes / Cabinets & Tops / Alternative Energy
GEOTHERMAL IMAGE: UPONOR (WWW.UPONOR-USA.COM)
PHOTO BY JOEL SILVERMAN
Earth Energy
A geothermal heat pump (GHP) uses refrigerant-filled underground
piping loops, installed horizontally or vertically, to exchange heat
with the earth. These systems work well in both warm and cold
climates. A good GHP is able to move three to five times more
energy than it consumes. Models are available for use with forced-
air or hydronic distribution systems. While the hydronic models
don’t get water as hot as a conventional boiler (122 °F, compared
to 150 °F or more) their low temperature output is a perfect match
for radiant floor heat.
DOMESTIC WATER HEATING
Multiple Options
Water heating accounts for 15 percent of your home’s energy use.
Most homes have reservoir-type water heaters. In these, gas, pro-
pane or electricity heats water that is stored in a 50- or 80-gallon
tank. The unit maintains the water at a set temperature, often
between 120 and 135 degrees, so you have hot water when you
need it. If it is time to replace your unit, and you want another
tank-type model, be sure to select a high-efficiency Energy Star-
certified model. Better yet, consider a “hybrid” electric heat pump
water heater, such as GE’s Geospring. These water heaters extract
heat from the surrounding air to pre-heat water, and are up to 65
percent more efficient than conventional tank-type heaters.
A tankless water heater is another option. As the name implies,
these don’t waste energy keeping water hot in a storage tank—water
that may not be used for hours; instead, water is heated on demand,
when it is needed. Gas condensing heaters are even more efficient,
because they capture the heat that would otherwise be lost in the
exhaust gases and use it to heat water via a heat exchanger. Tank-
less water heaters are a natural fit with radiant floor heating (p. 42).
Recirculating pumps are another way to boost efficiency. In
larger homes, if the heating unit is far away from faucets and
showerheads, you can waste a significant amount of water (as
much as 40 gallons per day) waiting for the hot water to reach its
destination. Recirculating pumps move water from the source and
back again, creating a continuous loop, so no water is wasted. The
pump is activated by a motion sensor and shuts off automatically.
Finally, “smart” technology is making water heaters more ef-
ficient by allowing demand response. This means that the unit
can be programmed to delay water heating during periods of high
demand on the electrical grid. Smart water heaters can also be
managed from afar, so they can be turned down if you are going to
be away for several days, for instance, and turned back up shortly
before you return. GB
VISION HOUSE® AT MARIPOSA MEADOWS SPONSOR
Uponor AquaSAFE Fire Sprinklers
Uponor AquaSAFE fire sprinkler systems give
homeowners peace of mind in the case of
a fire. Tapping into the home’s cold-water
plumbing system, it uses just 10 to 15 gallons
of water per minute to extinguish a fire—
compared to the 250 gallons per minute that
are expelled from a fire hose.
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Glossary of Terms
Know the Lingo
■■ Annual Fuel Utilization Efficiency (AFUE): The percentage
of a fuel’s potential energy that a furnace or boiler converts
to usable heat. Government standards that take effect in
2015 require AFUE levels of 82% for gas boilers, 83% for oil
boilers, 80% for gas furnaces and 82% for oil furnaces.
43
■■ Air Handler: In a forced-air heating or cooling system, the
air handler unit moves heated or cooled air through the
home’s ductwork.
■■ British Thermal Unit (BTU): The unit of measurement
for heat, whether it’s the heat given off by burning fuel or
extracted from a home for cooling. Technically, one BTU is
the energy required to raise one pound of water one degree
Fahrenheit.
■■ Combustion Chamber: The part of a furnace or boiler
where the fuel is burned.
■■ Compressor: The part of the air conditioner or heat pump www.greenbuildermag.com 11.2015
that compresses and pumps refrigerant.
■■ Condenser Coil: The part of an air conditioner or heat pump
that releases heat from the surrounding air in cooling mode
and collects it in heating mode.
■■ Distribution System: The network of air ducts or hot water
pipes that delivers heat from a furnace, boiler or heat pump
to the home’s rooms.
■■ Evaporator Coil: The part of an air conditioner or heat
pump that exchanges heat with the air in the home.
■■ Heat Exchanger: Located in the furnace or boiler, it transfers
heat from the combustion chamber to the air or water in the
heat distribution system.
■■ Heating Seasonal Performance Factor (HSPF): The heating
efficiency of a heat pump. It’s a ratio of the heat it generates
over the heating season, in BTUs, to the watt-hours of
electricity it consumes. Heat pumps manufactured after
2006 have to have an HSPF of at least 7.7, but the best units
have ratings as high as 10.
■■ Seasonal Energy Efficiency Ratio (SEER): The cooling
efficiency of an air conditioner or heat pump. It’s the ratio
of cooling output to electricity used. The minimum SEER
requirement for units manufactured beginning in 2006 is 13.
■■ Zoning: A method of partitioning a home’s hydronic or
forced-air distribution system into independently controlled
comfort zones.
VISION HOUSE® AT MARIPOSA MEADOWS SPONSOR
Bosch Greenstar Combi 131 & Greenstar 79 Boilers
These gas-fired condensing
boilers from Bosch boast
efficiency ratings of 95 percent
AFUE and have earned the
Energy Star Most Efficient 2015
label. The combi boiler unit
provides space heating with
integrated domestic water heating. www.bosch-climate.us/greenstar