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Written by Suzanne Heibel   
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Tuesday, 21 October 2008

Passive Solar Design: An Easy Way to Green Your Home

Never heard of passive solar design? Passive solar design is just the ability of a house or building to utilize the sun to either heat or cool a house simply by its direction or shape. By constructing a building according to very simple design standards, homeowners are able to capitalize on the sun's energy and virtually eliminate the need for a thermostat. Greening the structure of your home is a wonderful technique for many people looking to make their home more eco-friendly and wallet-friendly.

Home Orientation

Imagining a home as a rectangular shape, it is important to face the longer sides of a home to the north and south and the shorter walls facing east and west. For the majority of the day the sun is in the southern sky, so the southern side of the building will have the most exposure to sunlight. For passive solar heating, the side receiving the most light is the important side to regulate in order to maximize the control over the most amount of heat energy at a time.

During winter months, the sun is lower in the sky, meaning the south-facing windows will receive a great deal of light and warm the house. In summer months, the sun is higher in the sky, so the south-facing side will not receive as much sunlight as in the winter months, but it will receive some. In order to prevent sunlight from warming the building, putting shades over the south-facing windows prevents sunlight from entering, thus cooling the house. At the same time, the building will receive a lot of natural light, preventing the need for electricity.

To further monopolize on this idea, a building should have very large windows on its southern side in order to let as much light or heat into the room. At the same time, the rooms in the house that require the most heating in the winter and cooling in the summer should be nearest to the south-facing side of the house.1

Concrete Floors

South-facing windows work great, but to utilize design to its fullest, buildings need to be equipped with materials that will absorb energy to provide heat to the building all day and night. Concrete is a material that has a high thermal mass, or a highly efficient ability to hold heat. By having concrete floors in a house with large south-facing windows, the floor is able to retain the solar energy and keep the house warm all night. Carpeting the concrete with a darker color, like dark brown or blue or green, means that much more heat will be absorbed. Lighter colors do not imbibe as much heat.2

Window Shades and Fans

Summer
During the summer when sunlight should only be used for energy, put outreaching shades up outside over the windows so light, not heat energy, will enter the house. Also lowering the blinds during the summer months during the daytime helps blocks the sun from entering and heating your house; by dusk you can open your blinds up again when the night has become cooler. Keeping ceiling fans on when people are occupying rooms also aids in room-cooling because air is constantly being circulated. However, if no one is occupying the area, turn off fans to save energy because they only need to be used when people are there to feel and enjoy their cooling effect.

Winter
In the winter time, keep the windows open all day to heat the room and floor, then have window shades or curtains over them at night to deter heat loss through exposed windows. Thicker materials such as heavy fabrics, work better to trap heat than metal or wooden shades (1). Window fans also aid in circulating the warm air in the winter, especially because hot air rises, so having a fan on can help bring the warmer air back down to where people can feel it. During summer months, turn the fan off when rooms are empty to save energy.3

Insulation

Although insulation is not a new idea for saving energy, it is an important concept to revisit. When people talk about turning buildings “green,” insulation is often omitted from the conversation since it is assumed that it is just part of construction (2)4. This is true, but without proper insulation, crucial heat in the winter will be lost and the thermostat will need to be readjusted to make up for this inconsistency.

To keep your home warm a good environmentally friendly choice is natural fiber insulation, which is composed mostly of recycled cotton.5 Because it is mainly made of recycled goods, manufacturing this product uses far less energy than regular insulation. To view more about eco-friendly insulation visit http://www.ecowise.com/green/insul/index.shtml.

A Simple and Cost Efficient Solution!

As an architect or home owner looking to remodel, there are many ways to build green, but with the use of passive solar design, green homes can be constructed by simply implementing an easy design. The idea behind south-facing windows is to put up an environmentally friendly building with no extra cost to the contractor. Yes, solar water heaters and photovoltaics are important concepts for energy savings at home, but these solutions may initially be a very expensive investment for many people. Solar panel installation can cost upwards of $100,000. But passive solar design is a house just oriented differently. There is no extra cost to the builder, and if you already own a home and looking to remodel, this concept could save loads of energy and provide a handsome change to your home. It is economically doable and socially and environmentally beneficial for everyone.

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1 http://apps1.eere.energy.gov/consumer/your_home/designing_remodeling/index.cfm/mytopic=10270.
2 Id.
3 Id.
4 http://www.insulation.org/articles/article.cfm?ID=IO070103.
5 http://www.ecowise.com/green/insul/index.shtml.




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