Go Green! (and Not Just a Little Bit)

So you are planning a building or remodeling project and you want to ‘go green’. Mainstream advice in the U.S. will steer you to the Energy Star/LEEDS standards — and your project will use 15% less energy than one ‘built to code’ — and 30% less than the average American home. Sounds pretty good, eh?

Well, not really. The German PassivHaus — using ordinary technology — uses only about 15% of that energy — a savings of 70% to 90%.

How? Basically it uses super-insulation, tight construction — especially closing off all ‘thermal bridges’ where heat crosses to the outside — advanced windows, controlled ventilation with heat recovery, a minimal bit of passive orientation and thermal mass, and efficient lighting and appliances. That’s pretty much it.

Oh, and for heat it relies on waste heat from the appliances and the body heat of the occupants. If occasionally some extra heat must be added it can be supplied through preheating the incoming ventilation. (More will need to be added if you live north of Lat. 60° N.) The 15% energy still used (sourced from renewables, if possible) is mostly for water heating and electricity generation.

In Germany, the system is already so well standardized that building or remodeling to PassivHaus standards costs no more than older construction methods. According to Wikipedia, the PassivHaus standards “originated from a conversation in May, 1988 between Professor Bo Adamson of Lund University, Sweden and Wolfgang Feist of the Institute for Housing and the Environment, Germany.” PassivHaus standards will become part of the European Union’s building code in 2012.

At least two have been built in the U.S. — one in Illinois and one in California. But there is an active design community in this country working to improve even these standards — the Zero Energy Home (ZEH) movement.

This doesn’t mean a building that uses no energy, but rather one that incorporates energy conservation strategies and energy generation onsite so as to offset all energy used with energy produced — thus, net Zero Energy.

The technologies used are very similar to the PassivHaus standards, but with the addition of minimizing energy used so that it is fairly easy and economical to generate enough energy onsite to replace it.

This minimizing focus means that ZEH designers explore a wider range of alternatives, like exterior shades, awnings, and shutters, solar hot water systems, and so on. Use of these unfamiliar systems requires an educated and motivated occupant to get the best results from them. As any parent who has followed a child around turning off lights, and closing refrigerator and house doors knows, the best system in the world won’t work if you don’t use it consistently.

So there you have it. Why settle for saving 15% off your energy bill, when you could be saving 70% to 90% — or even all of it.

Save With Your Appliances

In the typical U.S. home 20% of electrical energy used is used by appliances. The biggest users are, of course, those appliances with the intended function of producing heat or coolness — water heaters, clothes dryers, refrigerators and freezers, air conditioners, and so on.

At a minimum, the conscientious consumer should be sure to buy “Energy Star” appliances when it comes time to replace old ones. Some of these may cost a bit more up front, but will save enough off your energy bill to re-pay the difference fairly quickly. Each month after that your savings will mount, as will the corresponding savings of pollution and greenhouse gas costs — as each month you will be using less energy than you might have.

Simply becoming more aware of the way you use energy and appliances can also make an appreciable difference. There are many lists available of these “Do’s and Don’ts” containing such tips as:

  • Turn off unnecessary lights
  • Set refrigerator at 40 degrees F; keep coils dust free
  • Wash only full loads in the washing machine or dishwasher
  • Don’t use the pre-rinse or dry cycles of the dishwasher
  • Use power strips to turn electronics off when not using, etc.

If you can find it in your heart to really care about the impact of your home energy use, then take the time to search for the MOST efficient options available. One good place to start looking is at www.metaefficient.com/

Here are just a few examples of the kinds of options you will find:

  • Spin-dryers  (extractors) that remove most of the moisture from laundry, thus dramatically lowering drying time; also, “solar clothes dryers” — i.e. clotheslines and drying racks
  • ‘Instant’ tankless water-heaters, including at least one model that accepts pre-warmed water from solar water-heaters; and solar water-heaters too
  • Low-flush and ultra-low-flush toilets that use much less water
  • A toilet tank-top sink that allows you to wash your hands in water that then fills the tank
  • An induction hob — a European type of cook-top that works by magnetic field — it doesn’t produce heat and is 85% – 95% efficient
  • Sun Frost refrigerators and freezers
  • Compact fluorescent lights or LEDs; and so on and on

There are, in fact, so many different ways to save energy that anyone who wants to is sure to find several to like. Don’t forget though — the best way to save energy is “Don’t buy, and Don’t use” whenever possible.

How to Need Less Heating and Cooling

After your house is ‘tightened up’, that is you have insulation in place and ventilation rather than drafts, there are many other steps you can take to lessen your heating and cooling loads.

Wind protection is the first thing to consider in cold weather. As you know, there is often a big difference between the temperature and the chill index. Old farm houses long ago proved that a well-designed and well-placed windbreak can reduce heating costs by 20% to 40%.

In town, careful placement of evergreen trees and shrubs can slow the wind near the house. Sometimes it is possible to berm (pile earth against) the windward sides of the house. Lattice trellises furred out an inch or so from the walls and used to support thick evergreen ivy can help provide wind control in winter and shade in summer.

In hot weather, shading the house with deciduous trees can make a difference of up to 20 degrees — even more if it is breezy. Sometimes it is more convenient to use awnings to shade certain windows. Shade must be on the outside. Once sun hits the glass, the heat enters the house. If you have an old house with screens that cover the entire window, investigate “shade screens”. There are many new types of windows available with special coatings and gasses between their sealed panes that insulate better than older windows.

Taking advantage of a simple “stack effect” can help with summer cooling. This means bringing air into the house near the ground on the shaded side of the house and providing a free path for it to rise as it heats, then exits through larger high windows. The larger the temperature difference between intake and exit, the stronger the cooling circulation will be.

If your area usually cools down at night, another cooling option is the whole-house fan. This is a large attic fan that you run at night taking cooler intake air from near the ground, drawing it through the house, and exhausting it out the attic. You then close up the house in the early morning, and use small fans to circulate the cooled air.

The best way to achieve good daylighting without adding to your heating problems is by installing carefully sited solar tube skylights. Light tubes are like stovepipes, but reflective inside and capped with lenses at each end. Most do not open for ventilation. They are relatively inexpensive, easy to install, and no more likely to leak than a stovepipe. Solar light tubes in the kitchen, bathroom, and over reading areas can insure that you will never again need electric lights during the daylight hours. Daylight is also easier on your eyes.

Relatively simple changes like these can make a huge difference in your “energy footprint” and equally huge savings in your energy bills.

Heat

Thermal comfort for us humans falls within a narrow range of temperatures (extended one way or the other a bit by humidity, air movement, activity, clothes, age, health, etc.). Therefore, when the weather doesn’t cooperate, one of the main tasks of our shelters is to produce a thermal comfort zone for us.

Heat is actually a portion of the spectrum of electromagnetic radiation. It moves (from warmer to cooler) three ways:

  • Conduction is the movement of heat through solid objects, for example walls, ceilings and floors. The way to slow this movement is by using insulation. This works in both cold weather when you want to keep heat in, and hot weather when you want to keep heat out.
  • Convection is the flow of heat through liquids or gasses, like air. Uncontrolled we call it drafts, controlled we call it ventilation. “Draft-proofing” means installing weather-stripping and caulk to seal holes and cracks in the building.
  • Radiation is the way the sun’s heat travels to us through space. Radiation heats the bodies it reaches without heating the air first. Thus it is the most direct, and therefore the most efficient method of heating. It is also perceived as the most comfortable.

Our most common household heating is forced air (convection) which is inefficient. It heats air and blows it through ducts (usually uninsulated) where much of the heat is lost. Entering our rooms, it rises toward the ceiling instead of staying near the floor with us. Unless a humidifier is added it also lowers humidity to unacceptable levels, causing damage to furnishings and sinuses. Its’ chief virtues are that it is easier to tend, more comfortable, and more efficient than the woodstoves and fireplaces it replaced.

It is possible to raise the efficiency of woodstoves by providing two changes:

  • Combustion air must be provided to the airtight firebox from outside the house. Using warm air from inside the house will result in a net loss of heat energy.
  • The stove must be provided with enough mass. Then a small amount of wood burned in a quick, hot fire will heat the mass which will then re-radiate the heat to the room slowly over a period of several hours. These “masonry stoves” have been used in Sweden, Finland, Denmark, Germany and Russia since the “Little Ice Age” of 1500 – 1800.

We can also use the sun’s heat directly, but again only by capturing the heat from the sunlight entering our homes in enough mass to allow effective re-radiation — otherwise we would be limited to overheating during the day followed by fast cooling when the sun goes down.