Even in the heat of the south, passive solar and cooling design methods can increase energy-efficiency and provide sunny interiors. This 1 1/2 story 2100 s.f. home has average energy bills approximately 1/2 the energy consumption of other similarly-sized homes in the area. With a little less south glass than most passive solar homes, the home is technically sun-tempered.

House Siting - Orient the home with the long walls facing north and south. The front faces west so the south is the side of the home. There is an abundance of windows on the east to capitalize on the nice views in that direction. The land is heavily wooded and just enough trees were removed for the house. For full sun in November, more trees would need to be removed, but the owner is happy with less solar gain during that month and the extra shade during the summer.

South Windows - Place as many of the windows as possible on the south wall. Most of the windows are in the side sunroom, which also serves as the family entry. That is where boots, coats, and plants are kept in winter. The laundry area is partially hidden by a half wall that divides the room. South windows are also incorporated into the dining area and upstairs bedrooms. Because low-e windows with a high SHGC coefficient was hard to find locally, clear glass was used for the south windows to let in as much sun as possible.

Overhangs - Shade the south-facing windows with overhangs. At 31 degrees latitude in a hot climate (2600 cooling degree days), the appropriate length for south overhangs is 2'. This shades the windows just right for the 5' windows at a 7'8" head height on the 9' first floor wall.

Porches - add porches to shade east and west windows. Porches were added as much as possible where there were no east and west trees to shade the east and west windows. They also create wonderful outdoor living spaces on the front and back of the home.

Thermal Mass - add brick or concrete if south glass exceeds 7% of total floor area. With the amount of south glass, no extra mass was needed, but the concrete slab in the sunroom does help keep the temperatures comfortable year-round.

Separate Sunrooms - Include them only if the residents will use them. The sunroom was designed to be a living space. The temperature has never been above 78 degrees in summer nor below 65 degrees in winter, even when the family is gone and the heat pump is turned off. The doors and windows between it and the main house are left open year-round. The sunroom has glass primarily on the south.

Roofs - In hot climates, keep the roof color light to reflect the heat. A metal Galvalume roof was installed like many of the older farmhouses. It was installed over 1x4 treated sleepers 24" on center, perpendicular to the rafters to create an air space. The underneath side of the shiny metal roof performs like a radiant barrier.

Foundation - Slab on grade construction is a simple way to incorporate thermal mass. Since the home sits on a sloping lot, just the front 2/3 is on a concrete slab, but this is enough to help with the summer cooling of the home. No slab insulation was used because the house is in a very hot climate and the earth can be used as a heat sink.

Framing and Caulking - Seal all possible air leaks. In hot, humid climates, the vapor retarder is placed on the outside of the exterior walls. Caulk is placed between the exterior insulation board and the sill plate and between the exterior insulation and the top header plate. The exterior insulation board seams are then sealed with foil tape. The exterior headers were insulated with scrap pieces of insulation board between the (2) 2x12s. Energy-efficient corner construction was requested to allow for more insulation, but the framing contractor had a hard time grasping this idea. The owners stood ready with caulking gun in hand when the windows were being installed to assure that the flanges were caulked behind. The owners also performed additional caulking and sealing wherever daylight was seen from the inside.

Windows and Doors - Select high quality and install them correctly. Wood and vinyl casement and awning windows were used in the main house and double hung windows were used in the sunroom. Exterior doors are insulated metal units with clear glass.

Insulation - Install it carefully. Cellulose insulation was blown in the walls and the exterior is then wrapped with foil-faced rigid insulation. The ceiling has dense-packed cellulose between the rafters. The small crawl space area has 1" of sprayed glue-heavy cellulose and 4" rigid foam panels which were carried back from a trip to the dump.

Roof Ventilation - Get the heat out quick. An air space is provided below the metal roof. The typical foam roof closures at the top (beneath the ridge) and bottom of the PBR metal ribs were eliminated to allow for better ventilation. It has been discovered, unfortunately, that flying squirrels like those spaces, too. Vented closures should have been used in their place.

Exhaust Fans - Get the moisture out of the house fast. The baths are vented either through the wall or ceiling cavity to the outside. The gas range is vented through an upstairs closet and then out through a wall. The visible portion of the range hood duct was made to match the wood stove flue. The Sears variable speed unit is quiet.

Heating and Cooling System - Put it inside the house and do not oversize it. After much discussion, the mechanical contractor agreed to put in a smaller three-ton heat pump with variable speed blower. It has never failed to meet the cooling load even during the hottest, most humid days. The unit is inside conditioned space in a walk-in attic although there are no air vents to this space. The medium-size wood stove easily heats the entire house when used instead of the heat pump. The awning window nearby is opened slightly for intake air. (Awning windows crank open and are hinged at the top.) The thermostat is kept on 70 degrees F in winter and 76 degrees in summer. There is no fresh air intake in the duct system, but a blower door test indicated that the house still met the recommended minimum of .33 air changes per hour. (In newer, tighter homes, additional fresh air is typically needed.) The air conditioning is seldom turned on before June - about a month later than most homes in the area. The heat is seldom turned on before November - about a month later than average in the area. For two months in the spring, and two in the fall, the windows are left open quite often. The power was out in the middle of summer for a week after a hurricane, yet the house stayed tolerably cool (not more than 80 degrees F) even though the humidity was high. Opening the windows at night brought in cooler air, which stayed in the house when the windows were closed in the morning.

Lighting, Ceiling fans, and Appliances - Install the most energy-efficient models. Ceiling fans are used year-round in the bedrooms. In the summer, they are turned on in occupied living areas. There is no recessed lighting and all of the lights are fluorescents. Daylight bulbs were used in the indirect light boxes built above the windows. The refrigerator is basic, yet energy-efficient. The washer was recently replaced with an Energy Star front loader that takes more moisture out of the clothes. Clothes are line-dried about half of the time. A simple solar hot water panel with integral storage is installed just above the water heater on a south-facing roof. Propane is used only for cooking and amounts to one 5-gallon bottle per month.

Energy Consumption - A modest life-style can reduce overall energy consumption. The 2100-square-foot homes energy bills have averaged less than $100/month for three occupants since 1999. About 10% is propane for cooking. Looking at just the electrical consumption, which includes the heat pump and hot water, the average monthly consumption is about 700 KWH. The highest usage in winter (about 900 KWH) is in December and includes Christmas lights and company. The highest usage in summer is about the same in August with the air conditioning running full time and company for two weeks. In mild seasons, where little heat or air conditioning is used, the average monthly electrical use for lights, some water heating, and all household appliances averages around 450 KWH/month. This leaves an average of 250 KWH/month for heating and cooling. It is common for neighbors with similar size homes to see energy bills 3-4 times these amounts during peak heating and cooling seasons.

Costs of Energy Features - The energy features increased the construction costs by about 4%. This includes the cellulose insulation, better windows, and an upgrade in heating/air conditioning equipment. To borrow the extra money increases the mortgage payment, but when this cost is subtracted from the energy savings, the net savings are still over $100 per month compared to neighbors. However, what the owners enjoy equally is the thermal stability that the home maintains year-round. Comfortable temperatures and an abundance of sunlight make the house a delightful place to live.