3
Green Home Construction - Systems
Does Green Cost More?
• Calculate ROI
• Consider:
Cost
44
Benefits
Initial cost
Seasonality
Tax benefit
Energy savings
Utility company
rebates
– Home resale value
–
–
–
–
–
DSIRE Database
• Database of State
Incentives for
Renewables and
Efficiencies
• Check out the DSIRE
database for credits,
incentives and
rebates by state.
• www.dsireusa.org
45
What Do I Need to Know?
You don’t:
• have to remember all of
the technical details.
You do:
• need to know how the
systems
– contribute to the greenness
of a home.
– affect a home’s economy.
– enhance living environment
and comfort.
47
HVAC Ratings
HVAC System Ratings
Stands for
Applies to
Calculation: Is higher or lower better?
Central air conditioners
and heat pumps
Amount of cooling (BTUs) divided by Electricity (watts) consumed over a
year’s performance. Higher is better. The higher the SEER rating, the more
energy efficient.
SEER
Seasonal Energy Efficiency
Ratio
EER
Energy Efficiency Ratio
Air conditioners
Same as SEER but evaluates one point in time or a particular set of
conditions (temperature and humidity.)Higher is better. The higher the EER
rating, the more energy efficient.
HSPF
Heating Seasonal
Performance Factor
Furnaces
Amount of heat produced (BTUs) divided by electricity (watts) used. Higher
is better. The higher the HSPF rating the more energy efficient.
AFUE
Annual Fuel Utilization
Efficiency
Gas and oil furnaces
Heat output divided by total energy consumed. Higher is more energy
efficient. AFUE 90 means 90% of energy is transformed into heat. Electric
heating is AFUE 100%. (Say A-few)
CFM
Cubic feet per minute
Ventilation
Length x width x height of space divided by frequency of air change. The
higher the number the faster the change of air in the space.
ACH
Air changes per hour
Ventilation
CFM divided by volume (length x width x height) of space. The higher the
number the greater frequency of complete air changes per hour.
COP
Coefficient of
Performance
Heating, cooling, and
heat pump
BTUs produced divided by BTUs of electricity used
Higher is better. The higher the COP, the more efficiently energy is
consumed for heat or cooling.
48
System Ratings
• Cooling and heating systems
are measured in BTUs (British
Thermal Units)
• SEER (Seasonal Energy
Efficiency Ratio)
– SEER is the most common
performance rating.
– Air conditioners must achieve
a rating of 13 or higher.
– Energy Star air conditioners
must achieve a minimum
rating of SEER 14 and 11 EER.
49
Rightsizing
• Matching the capacity of the
cooling unit to the size of
the home
• Considerations:
– climate zone
– day and nighttime
temperatures
– humidity levels
– size and layout of the home
– tightness of the building
envelope
49
• An over-capacity system will
cool a home quickly, but will
not adequately remove
humidity.
• Frequent cycles create
temperature swings and
cause wear and tear.
Cooling Systems—In Brief
Efficiency reduced
Green options
Energy Star Ratings
IAQ considerations
Programmable
thermostat
• Information sources
•
•
•
•
•
50
High-Efficiency Furnaces
• More efficient, more
costly
• Costs vary – get
multiple estimates
• Different rating
systems may confuse
clients
51
Heating Systems—In Brief
•
•
•
•
•
•
•
•
•
Low efficiency (AFUE 68%–72%)
Mid efficiency (AFUE 80%–85)
High efficiency (90%–97%)
Potential energy wasters
Green options
Energy Star AFUE ratings
IAQ considerations
Energy-thrifty thermostat settings
Information sources
53
Green Choices
Zoned systems
Condensing
furnaces
• Divide the home into areas (zones) with
similar heating needs
• Uses the heat from water vapor in the
exhaust for more efficiency. The best
types resist corrosion.
Sealed combustion
• Uses outside air for intake and exhausts
to outside
Electronically
commutated motor
• Motor speed varies based on air
pressure – more constant flow of heat,
increased efficiency.
53
Rightsizing
• Matching furnace capacity to home size and
climate
• Too small will not provide adequate heat.
• Too large produces wide temperature swings
plus wear and tear of frequent cycles.
• Homeowners should look for contractors using
software to right-size.
55
Active Solar Heating
Hydronic systems
• Uses liquid (water or
antifreeze solution) as the
radiant collector.
• Works well with radiant
flooring
• Takes longer to heat but
provides a constant
temperature.
54
Air systems
• Air is heated between a
black glazing and
collector, then a fan
distributes the heat
indoors.
• Air is a less efficient
conductor of heat.
Passive Solar Heating
Requires five
components:
56
• Aperture (collector): Where sunlight
enters the home
• Absorber: A hard darkened surface that
absorbs the heat.
• Thermal mass: Lies behind the Absorber
and also absorbs heat
• Distribution: 3 modes − conduction,
convection, and radiation
• Control: Provides shade when heat is
unwanted.
Trombe Wall
• The space between the
panes of a double pane
glass wall is filled with
water.
• The water absorbs solar
energy without blocking
the benefit of natural
illumination.
56
More Green Heating Choices
Radiant Heating
• Best use is a small space.
• Heats people, not a room.
Radiant Floor Heating
• Hot water circulates through pipes in the subfloor.
Air Source Heat Pump*
• Uses heat transfer to heat and cool.
• Best use is in moderate climates.
*Image: www.energystar.gov
57
Geothermal Heating and
Cooling
• Provides one of the
greatest energy
savings.
• Underground loops
circulate liquid that
absorbs (for heating)
or relinquishes heat
(for cooling).
59
Ventilation—Green Choices
Natural
ventilation
Whole house fan
• Most green
• Uses the “chimney effect.”
• Enhances natural ventilation.
• Windows MUST be open when operating.
Heat recovery and
• Moves warm air to or away from desired
energy recovery
locations.
ventilation
60
Indoor airPlus
• Heating, cooling, and
ventilation systems
impact indoor air
quality.
• The EPA Indoor airPLUS
certified home is
energy efficient, emits
few greenhouse gases,
and provides a healthy
indoor air quality.
62
IEQ
• The quality of the inside
air and environment that
affects the health,
comfort, and
performance of
occupants;
– Acoustics
– Glare
– Thermal comfort
– Aesthetics
– Controls
62
Incandescent, CFLs, LEDs
CFL
Incandescent
LED
Lighting
characteristics
Delayed,
white/blue
Immediate,
Warm amber
Immediate,
multi-color,
unidirectional
(spotlight)
Very low heat
emission
Dimmable
Yes, newer
models
Yes
Life
Long
Med
Very long (25k
hours)
Cost
High but
dropping
Low
High
Efficiency
High
Low
Best
63
Light Bulb Ban?
• Energy Independence
and Security Act
• Phase out the
manufacturing of
incandescent bulbs
• Consumers are mixed:
–
–
–
–
–
64
CFLs:
Produce a cool light,
Have a delayed-on
Cost more
Contain mercury
Daylighting
• An effective strategy
balances illumination
needs with thermal
comfort.
• Starts with initial
home design
including sunlight
patterns and angle of
the site.
65
Energy Star Appliances
Benefits
1. Lower energy costs
2. Tax credits, incentives,
and product rebates
66
• Estimated savings:
Refrigerators—20%
Clothes washers—37%
Dehumidifiers—15%
Dishwashers—10%
Freezers—10%
Room air cleaners and
purifiers—40%
– Water heaters—10%–
20%
– Water coolers—45%
–
–
–
–
–
–
Water Heater Selector
• Many energy
efficient, waterthrifty options.
Make the right water
heater choice with
this online selector at
www.energystar.gov
68
Green Choices
Insulation
Solar hot water heater
On-demand watercirculation pumps
Tankless water heaters
Tankless coil indirect
water heaters
Drain water heat
recovery systems
68
• Simply wrap the hot water heater tank.
• Options are available based on climate
• Fully dependant or supplemented with a heater
• Instant hot water to the faucets
• No energy is wasted to maintain a temperature
• Uses the furnace as the heater
• Recovers the heat from used water
EPA WaterSense
Promotes efficiency
Qualifies products, new homes
Decreases indoor and outdoor water usage
Helps consumers make water-efficient choices of
products and services
• Helps consumers adopt simple daily activities to reduce
water usage
• Establishes certification criteria
• WaterSense homes can save up to 10,000 gallons of
water a year
•
•
•
•
70
Greywater
• Potable wastewater –
reusable water from
low-contamination
uses like dishwashing,
laundry, and bathing.
• Requires dual
plumbing system
71
Greywater
Cautions
• May be used in applications
such as irrigation and toilet
flushing.
• Water may require treatment
before reuse.
• Treatment methods include:
– Filtering
– Disinfection
– Settling tanks
• Qualified professionals should
be consulted.
• Care should be taken for
irrigation.
71
Water Management Outside—
Green Choices
Pervious
surfaces
Bioswales and
rain gardens
• Allows rainwater to
seep, prevent soileroding
• Designed to collect
rainwater run-off,
mimicking natural
wetlands
Rain barrels
Xeriscaping
• Collecting rainwater
from a downspout
• Purposeful planting
of drought resistant
plants
Outdoor Water Conservation
73