Green Home Construction - Systems 3. Does Green Cost More? CostBenefits Calculate ROI Consider: – Initial cost – Seasonality – Tax benefit – Energy savings.

Green Home Construction - Systems Green Home Construction - Systems 3

Does Green Cost More?

• Calculate ROI• Consider:– Initial cost– Seasonality– Tax benefit– Energy savings– Utility company

rebates– Home resale value

44

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 RatingsHVAC System Ratings

Stands for Applies to Calculation: Is higher or lower better?

SEERSeasonal Energy Efficiency Ratio

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.

EER Energy Efficiency Ratio Air conditionersSame 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.

HSPFHeating Seasonal Performance Factor

FurnacesAmount of heat produced (BTUs) divided by electricity (watts) used. Higher is better. The higher the HSPF rating the more energy efficient.

AFUEAnnual Fuel Utilization Efficiency

Gas and oil furnacesHeat 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.

COPCoefficient of Performance

Heating, cooling, and heat pump

BTUs produced divided by BTUs of electricity usedHigher 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

• 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.

49

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

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.

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.

54

Passive Solar Heating

56

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

*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

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, LEDsCFL 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:– CFLs:– Produce a cool light, – Have a delayed-on – Cost more– Contain mercury

64

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

• 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%

66

Water Heater Selector

• Many energy efficient, water-thrifty options.

Make the right water heater choice with

this online selector at www.energystar.gov

68

Green Choices

68

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 

Outdoor Water Conservation

73