Passive Solar: Is Passive Lunar the Next Big Thing?

Daniel Chang emailed me a few days ago with some cynical observations about the state of passive solar in Austin and in the country today. “Maybe passive lunar contemplation will lead to something,” he says.

As we all know, active solar and solar panels get all the hype while passive solar design is often invisible to the untrained eye. To most people, “solar energy” is active solar. But passive solar is still a reality, just like the thermal properties of stone, earth, and wood are an enduring reality.

A quick survey of information about passive solar shows that, although architects and builders in parts of the country are using passive solar concepts, there’s no discernable trend toward increased use of passive strategies. So although passive solar is effectively free (can you imagine a national TV campaign for free passive solar?!?) there’s still plenty of room for improvement — and for increased energy and utility bill savings. For a lot of homeowners and commercial property managers, this is money on the table just waiting to be taken, but these savings have to be realized well before the construction stage.

Our key discovery was a report entitled Energy Policy by Kelly Kruzner, Kristin Cox, Brian Machmer, and Leidy Klotz. In it, the authors performed a satellite image inventory of 1000 homes across the country and evaluated the homes for their orientation to prevailing sun, roof color, and sun/shade exposure. They found that home orientation in some parts of the country is trending toward conforming with passive solar strategy — but at the same time roof color in many areas of the country is counter to passive principles. And as mentioned earlier, there’s no trend overall toward better passive solar design.

Here’s hoping passive solar becomes more well-known. There’s no reason it shouldn’t be.

Use Passive Solar Energy to Save Electricity

Passive solar design tips courtesy of South African writer Anne Erasmus. These ideas should give you the gist of some of the basic modifications and design approaches in the school of passive solar energy.

Harnessing passive solar energy in the form of heat and light and designing your home to maximize or minimize it, can make a difference in the amount of power you need to use to heat or cool your home.

Consider these points before finalising your plans for a new home.

1. High ceilings are better for hot climates, as the hot air will rise high enough to keep the lower living areas cool. Low ceilings in colder climates help to keep rooms warmer.

2. Look carefully at where you will need light in each room, and plan windows accordingly. That way you won’t need to switch lights on in the middle of the day.

3. Plan most of your windows and door openings to be on the side of the house where they will be more beneficial in terms of heat and light. In hotter regions, you’ll want doors and windows to open onto cool, shady areas that will send cooler air into the house, and in cold regions, you’ll want to let the heat in.

4. Insulate – as much as you can. Ceilings, floors, walls, doors, windows and even electrical outlets can be insulated. Insulation helps to maintain your home’s temperature – keeping heat or cold out or in.

5. A ‘Mudroom’, or separate entrance area allows people to enter or exit without exposing the rest of the house to outside temperatures.

If your house is already built, you can add a few items that will help maintain the indoor temperature without breaking the bank – or the house.

1. Insulation can be added to existing homes in ceilings without major work. Check doors and windows for drafts, and insulate them if necessary.

2. Retractable awnings are great for windows and doors that get a lot of sun in summer, and they can be pulled back in winter to help warm the house up.

3. Consider planting tall, deciduous leafy shrubs or small trees in pots near windows and doors. In winter when they lose their leaves the sun will reach in, but in summer they will provide shade and keep the air cool.

4. Shutters or insulated window coverings can help quite significantly in keeping heat in or out of your home.

5. Paint your roof white – it reflects instead of absorbing the heat of the sun.

Most of these tips will help to heat or cool your home by using, or deflecting, the natural energy of the sun. You may still need air-conditioning, fans and heating, but they will work more efficiently, and you’ll need to use them less often.

Manipulating solar energy to conserve electricity makes sense. Not only will it save you in power bills, but it is better for the environment. For more information on alternative energy sources, visit .