Energy Efficient Buildings

Energy Efficient Buildings E/3 Houses and Simulation

E/3 House Design/Retrofit Process

1) Ensure that entire design team of owner, architect, engineer and builder is committed to energy efficiency before pre-design phase. Designate energy consultant within team to coordinate energy efficiency efforts.

2a) For new building, design a “base-case building” with same floor area as proposed building, equal glazing area on all sides, standard efficiency HVAC equipment and appliances, and constructed so that it meets applicable codes such as ASHRAE 90.1. Simulate annual energy use of building using energy simulation program.

2b) For existing building, collect energy billing data and information about building. Simulate annual energy use of building using energy simulation program. Calibrate simulated energy use to existing energy use.

3) Complete a parametric analysis of base case or existing building to determine sensitivity of annual energy use to specific load components, appliances and HVAC equipment.

4) Using parametric analysis as guide, develop preliminary design solutions to eliminate or reduce loads from base case or existing building and incorporate high efficiency appliances and HVAC equipment.

5) Incorporate preliminary design solutions into computer model to estimate energy use of low-energy building. Iterate as needed to produce final design. Use computer model to estimated energy use of low-energy building. Compare energy use of base-case and energy-efficient building.

5) Rerun simulations before changes are made during construction to verify that changes will not adversely affect energy performance.

6) Commission construction, equipment and controls to ensure proper functioning. Educate building operators how to operate building to maximize energy performance. E/3 House Checklist

Orientation Long axis of house runs east-west to maximize solar exposure in winter and minimize solar exposure in summer

Landscaping Berm or conifers on north side to block wind Deciduous trees and vines on south, east and west to shade in summer and allow sun in winter Shade air conditioner condensing unit Native plants for evaporative cooling, shade and low ground reflectivity with minimal extra watering requirements

Walls Minimize wall area Minimize framing and avoid metal studs Thick, high-R insulation: R-15 minimum Polyisocyanurate or EPS sheathing Tyvek over sheathing to minimize moisture and air penetration High thermal mass on inside to reduce peak loads and store solar energy Use sustainable materials: wood, cast earth, straw bales, cellulose, etc.

Ceilings and Roofs Light colored roof to reduce cooling load Adequate attic ventilation to reduce cooling load Thick, high-R insulation: R38 minimum Radiant barrier on underside of attic

Windows Casement or awning style to minimize infiltration Double glazed, low-e, argon-filled, vinyl frame for low U Increase window area on south exposure for solar heating Reduce window area on east-west exposure to reduce cooling load South windows have high SHGF and overhangs East-west windows have low SHGF All windows have high visible solar transmittance daylighting. Insulating shades at night

Infiltration Tight construction: max 0.5 ACH Forced ventilation with air-to-air heat exchanger Double or shielded entry on lee side

Ground High-R perimeter insulation High thermal mass floor Basement or earth-coupled living space, especially in very hot or very cold climates

Electrical Equipment Maximize daylighting to reduce use of electric lights Fluorescent and compact-fluorescent instead of incandescent lights Energy efficient appliances (refrigerator, TV, computer, dishwasher, clothes dryer)

Hot Water Low-flow showerheads Water-efficient washer and dishwasher High-efficiency hot-water heater: minimum EF = 60%

Heating and Air Conditioning Return air in every room Night set-back thermostat High efficiency condensing furnace or boiler: minimum efficiency 90% High efficiency air conditioner: minimum SEER = 16 GSHP or evaporative cooling for appropriate climates

Renewable Energy Solar thermal hot-water heater Solar photovoltaic electricity Purchase wind electricity

Occupants Energy conscious