While the assistance of professionals is certainly important for maximizing energy efficiency, you can achieve a lot on your own. Here are tips to help, whether you are building or remodeling.
1. Design for conservation.
The easiest and least expensive way to control your energy cost is to reduce your energy demand. The simplest way to do this during the planning stage is to avoid building bigger than you need. Reducing the area that you must heat and cool reduces both construction costs and ongoing energy costs. As an added bonus you’ll spend less time and money cleaning and maintaining all that space.
Designing smaller doesn’t mean going without. It’s more a matter of planning space efficiently. Study your present home and lifestyle. Notice how you use space and how traffic flows. Look for ways to eliminate hallways and “dead space” and reduce or eliminate spaces that you use infrequently. For example, unless your lifestyle includes formal entertainment, consider eliminating a formal dining room or living room. Instead give a little more area to a great room. Beware of designing solely for the “wow!” factor featured so prominently on home design television. Once that initial “wow!” quickly wears off the next “wow!’ generally comes when you get your utility bill.
Enlist the help of your environment in your design. Site your house to capture solar energy in cold climates. In areas where summers are hot make sure you are shielded from the sun in summer. Good passive solar design can reduce your energy needs by 30% or more at almost no additional cost. Concentrate window openings on the south and east side of your home unless you live in a desert where cooling will dominate your energy demand. Choose energy efficient windows, usually those with double or triple panes and low emissivity (low-E) coatings.
Size roof overhangs to shade windows in summer but not in winter. Such overhangs are generally wider than those found in stock house plans so you’ll probably need to point out your desire to your contractor. An overhang of 2-3 feet controls sunlight in most situations and offers the added benefit of allowing you to let in refreshing breezes even when it rains.
2. Insulation is often the best energy investment you can make.
An extra thousand dollars spent on more or better insulation may quickly save several times that amount while keeping your home more comfortable and healthier.
Mention insulation and most people think of fluffy batts or blankets of loose fibers stuffed into the framing cavities between studs and rafters. But today there are a lot more choices. The key to an energy efficient home lies in matching the right product to you situation.
Insulation effectiveness is stated as its “R-value” a number indicating its resistance to the transmission of heat. A higher R-value means better insulating ability. Since R-values are determined by standardized laboratory tests, you can compare insulation products by their R-value. You can also increase R-values by combining materials with different values in separate systems.
I have a client in Arizona who is recycling an old barn into an energy efficient lodge. Because Rose Creek Lodge is entirely off-grid we’ve searched for cost-effective ways to reduce energy demand. A unique double roof system combines both conventional framing with structural insulated panels to achieve an R-value of over 60. Walls include 2×8 framing, R-24 insulation, plywood sheathing and 1” of rigid foam insulation covered with log siding for an overall R-value exceeding 30. These comparatively inexpensive strategies allow heating the entire lodge with a small propane heater even when outside temperatures drop into single digits.
Fiberglass batts are probably the best known and most frequently used insulation products in home building. Used correctly, they provide excellent insulation very inexpensively. Unfortunately it’s so easy to install fiberglass insulation poorly it has acquired an undeservedly poor reputation. To be effective, fiberglass insulation must completely fill framing cavities without leaving air pockets or compressed areas. Simply stuffing insulation behind wires or pipes and leaving pockets where batts join reduces their effectiveness dramatically. Obtain a copy of the insulation manufacturer’s installation guidelines and make sure your builder or insulation contractor follows them.
There are a number of insulation products available besides fiberglass batts many of which offer higher insulating values. Loose cellulose insulation can be blown into existing wall and ceiling cavities. Rigid sheets of polystyrene or polyisocyanate foam offer higher R-values than fiberglass or loose cellulose and have the added benefit of blocking air flow. Expanding foam insulation can also be sprayed into cavities where it expands to create a very efficient insulating barrier. Some foams are waterproof while others can absorb moisture so it’s important to match your selection to your environment.
Energy efficiency depends on more than insulation. A high R-value material that still allows air to circulate through it may be far less efficient than a product with lower R-value that also blocks the flow of air. If you are tackling a major project, such as a new home or major remodel, insulation advice from an energy efficiency expert can be invaluable.
To get the most out of insulation it’s also important to control the movement of air and moisture through wall and ceilings. Air infiltration barriers block air movement while allowing the passage of moisture. Placed outside of sheathing, beneath the siding, these fabric-like barriers stop air before it can get inside the wall. Allowing moisture to pass keeps it from accumulating inside the wall where it can provide a place for mold to grow or condense soaking insulation.
Vapor barriers block the passage of moisture and prevent moist air from getting into wall and ceiling cavities. This is especially important in cold climates where moist air escaping from inside your home can condense inside walls and ceilings either soaking and destroying insulation or creating a dark humid environment ideal for mold growth. In an existing home, water stained ceilings are more likely caused by such condensation than by a leaking roof.
Placement of vapor barriers varies with environmental conditions. In climates where heating is of more concern than cooling, vapor barriers should be placed between insulation and the interior. In warm, humid climates such as Florida or the Gulf Coast, the vapor barrier should be placed between the insulation and the exterior. Never use more than one barrier in a wall system. Using two barriers creates a space between them where moisture can’t escape. The result will be mold, ruined insulation and rotten wood.
Because vapor barriers play such an important role in the overall energy performance of your home, it’s best to talk to a professional about your particular circumstances. Look for someone trained in building science and energy efficiency. Builders and subcontractors may not be up to date on best practices for your situation.
3. Choose your heating and cooling system carefully.
Home design and insulation work with your heating and cooling system to determine the energy efficiency of your home. Careful selection of heating and cooling equipment can lower construction costs as well as reducing your monthly utility bill. Selection of equipment is often left to contractors and builders and may depend more on their relationship with suppliers or be limited to systems within their personal experience. Listen to their advice but look for a qualified second opinion.
In moderate climates that require both heating and cooling, heat pumps usually offer the best value in energy efficient equipment. Heat pumps move energy from cool to warm areas using principles of heat exchange. In summer a heat pump removes energy from inside your house and exhausts it to the warmer outside. In winter, the system reverses and extracts heat from the cooler outdoors and releases it indoors.
Basic heat pumps rely on air for energy exchange and are called air-air or air source heat pumps. At low temperatures, air source heat pumps can’t extract sufficient energy from outside air to provide heat and so must rely on much less energy efficient electric or gas backup heating systems. For this reason, if you live in an area where winter temperatures regularly fall below freezing, a standard air source heat pump is probably not your best choice.
Ground source heat pumps, or geothermal energy, represent a leap in efficiency over air source. These systems exchange energy between your house and the much more constant temperatures below ground. Even as outside temperatures fluctuate from scorching hot to well below zero, the temperature several feet below ground will remain fairly constant throughout the year. Ground source heat pumps typically extract energy from the earth through a series of wells or buried pipes. Although they cost more, their efficiency is so much greater you can often recover the additional cost in just a few years. As an added benefit, ground source heat pumps can be used to provide hot water for radiant floor heating or domestic uses.
Several additions to the heat pump field have extended their use to situations and climates usually limited to furnace or boiler/central air systems. Multi-stage air source heat pumps can function at lower temperatures than single stage systems, extending their usefulness into areas where temperatures may fall into the teens. Ductless mini-split systems work well in situations where you don’t have or want ductwork. These systems consist of interior and exterior units connected by a conduit containing tubes and wiring with the heat exchange fluids. The two units can be located some distance apart which makes them easier to use in areas where it may not be possible to locate the outside unit close to the interior unit. Because they don’t rely on ductwork, mini-splits are especially good in retro-fitting older homes that lack a duct system or additions where it isn’t possible to extend the ductwork.
Many people consider radiant floor heating systems to be the “holy grail” of staying warm. Radiant floor systems rely on fluid circulated through plastic tubing located in or below the floor. The fluid may be heated by a boiler, tankless water heater, solar hot water heater or ground source heat pump. Radiant systems don’t have ductwork so you won’t experience the loss of efficiency that can come from poorly sealed ducts. Unless you install it yourself, radiant systems can be quite costly. They also don’t offer a means of cooling so in some climates you’ll have to add in the cost of a separate cooling system. In my own experience, designing properly and investing in insulation may allow you to heat and cool your home with a less expensive system.
The choice of heating and cooling systems depends on factors that vary greatly around the country. For the greatest efficiency it is important to work with professionals in designing and installing your system. When selecting a professional be careful that you choose someone who specializes in energy efficiency. Many heating and cooling contractors still rely on rules of thumb and guesswork (they may call it “experience”) to design and size systems. While experience is a valuable thing, the world of energy has changed dramatically in the last decade. New materials and methods are appearing regularly.
Even if local building codes don’t require it, insist that builder or subcontractor design and size your system based on Manuals “J” and “D” of the Air Conditioning Contractors of America (ACCA). Insist that they provide you a copy of calculations in case you want to review them with an energy efficiency specialist. Failure to follow these guidelines often leads to an oversized system as the contractor builds in a “little extra—just in case.” In addition to the additional cost of oversizing, such systems operate inefficiently, raising your energy costs and reducing equipment life. Oversized air conditioning systems, for example, cool so quickly they don’t run long enough to dehumidify. The result is a clammy, mold-prone interior with equipment constantly cycling on an off for just a few minutes at a time.
4. Use renewable energy wisely.
With growing concern over global climate change and greenhouse gases, many people are looking for ways to not only save on energy costs but to do it in a way that protects the environment. Federal, state and local programs even offer financial incentives for installing conservation measures and clean energy systems. Explore ways you can reduce your “carbon footprint” and your environmental impact. Be careful, however, that you choose tested alternatives and understand the costs, benefits and liabilities. The area of alternative energy is currently the “wild west” of building technology with many unproven and impractical ideas floating around.
For example, consider the effects of disconnecting your home from the power grid and getting all of your electricity from solar energy. The photovoltaic array and equipment necessary to fully power your home will probably cost from $20,000-$80,000. At the lower end of this range, tax incentives and rebates may cover enough of the cost to make this attractive, but in most cases, you won’t live in the house long enough to recover your costs. You could remain connected to the power grid and install a smaller system that simply supplements and reduces your demand for grid power. Such systems typically cost $10,000-30,000 and will still take a long time recover costs.
As an alternative contact your local utility company and ask if you can purchase green power. Many utilities now offer energy generated from renewable sources such as wind, solar, hydroelectric or geothermal. The utility usually charges a small premium but you will be encouraging the development of renewable energy. Recognize that the actual power coming to your house may not be green but your purchase will reduce the amount of non-renewable energy used by the utility by the amount of your purchase. This will achieve your goal of contributing to the use of renewable energy without the hefty costs of installing your own system.
Consider solar water heating for your domestic hot water needs or for radiant floor heating systems. Hot water is the second largest consumer of energy in your home and solar hot water systems are efficient and affordable. Because sunlight isn’t always available, you’ll need a backup such as a tankless hot water heater.
As you can see, strategic planning holds the key to maximizing your energy efficiency.. Don’t assume that spending more automatically means greater efficiency. Instead, invest some time in research or some money in talking to an energy efficiency consultant and lay out a plan that will keep you comfortable year round.
This is a long version of a story that ran with pictures in the Spring 2008 issue of Custom Wood Homes magazine.
Jim Cooper is a former general contractor and author of Log Homes Made Easy. He consults in energy efficient and sustainable construction and is a member of the US Green Building Council. He can be reached at firstname.lastname@example.org.