Q&A.

Q: We have a small (750 sq feet) house that is livable but needs work. We are looking to increase our living space. Should we build an addition onto the existing structure or plan to construct a new separate home? What are the pros and cons of each option?

A: There is nothing wrong with building a new home, but some considerations need to be assessed. New construction requires an investment and it is not getting less expensive; do you have that capability? A new home will give you the opportunity to design what you want. What will you do with the old home? Selling it will help fund the new home, but where will you live during construction? Renting it will provide income and, at the moment, seems to be a popular way to help secure your future. Who will design your home, an architect or draftsperson or a design/build construction company? How will you choose a builder, and are they familiar with sustainable construction, which not only looks at the economic bottom line but also the environmental/ health and social bottom line. Building a new home is a large undertaking. On the upside, you get what you want (read 'can afford') and have a brand new home that fits your needs.

Expanding your existing home presents different considerations. Additions have less impact on the environment. The site already has a house on it; no new land is being developed. A smaller investment is needed; maybe you don't need a bank. Additions increase the value of your home and you have a place to live during construction. If going to a lender, you can roll in the cost of remodeling the existing home during construction.

Other considerations related to the question are the following: do you want to move away from the neighborhood and friends? Will children have to change schools or leave their friends? Do you need a refreshing change in your life? Building new or adding on deserves in-depth study and will ultimately boil down to your personal needs. You don't have to do it alone, either; ask friends and family and talk to professionals who are involved with each choice. Take your time, weigh every option, and you are sure to be happy with your choice.

Marcus Renner is chair of the Western NC Green Building Council, he teaches sustainable construction classes at ASU, and during the day he works for Appropriate Building Solutions, Inc, an area sustainable construction company. He can be reached at [e-mail] or 828-350-0451.

Q: I want to buy a window unit air conditioner. What are the pros and cons, what should I look for, and how can I get the right size for my room?

A: For those of us that don't have central air-conditioning, a window-unit may seem like an appealing option during the warmer summer months. There are a few things that you should know about before making your purchase, and a few things that will help you squeeze the most comfort from it, once installed.

First, you must decide how much space you're going to cool with this window-unit. If you're going to try to cool your entire house with a window unit, it may be in your best interest to use two units, since they will provide a more efficient distribution of air to all spaces.

See the chart in the next column to correctly "size" your unit.

Do not buy a larger unit than you really need, as this will decrease the air conditioner's effectiveness at removing moisture from the living space and decrease operating efficiency. Moisture plays a large role in the comfort of the space, so ... Bigger isn't always better!

The technology of an air conditioner is the same as your refrigerator or a dehumidifier. An evaporator coil cools the interior (in this case the room) and the condenser coil releases the heat outdoors. Refrigerant is moved by a pump through tubes between the two coils to transfer the heat. A fan blows the interior air over coils, which removes the heat from the air, and then returns this same air into the room.

When the refrigerant takes this heat to the outdoor-side of the air conditioner, it wants to release the heat to the outdoors. Therefore, the cooler the surroundings, the better. If possible, put the air conditioner in a window that faces north or is shaded. Keeping the air conditioner out of direct sunlight improves its efficiency.

Ceiling fans (or other fans) can be used to move air around within your home. This will help spread the cooled air as well as provide evaporative cooling against your body (evaporating your body's perspiration).

As far as efficiency goes, the more you spend upfront, the more you save over the long-haul. So, invest a few more dollars; it'll pay you back quickly. The efficiency of window units is typically described with an EER Rating. Anything above ten is considered pretty efficient these days.

Experiment a bit to determine the highest temperature setting at which you can be comfortable. Try 78 degrees F to start. Every degree higher will save about four percent in operating costs.

If you have a whole-house fan, you can save substantially on your electric bill by using the fan at night when weather conditions permit: usually when the outside temperature falls below 78 degrees F, and the humidity is not oppressive. But early in the morning, before the temperature begins to rise, turn off the fan and close the windows to capture the cool air. With this charge of cool air, the house can "coast" without the air conditioner until late morning or early afternoon. The whole-house fan should be air-sealed and insulated if it is not used during the air conditioning season, and air-sealed/ insulated during the winter to prevent the loss of warm air, which likes to rise through holes in the top of your house.

Window units, if left in place during the winter, should be wrapped on the inside, and weather-stripping should be used to block air infiltration around the unit (this applies to winter and summer). If wrapped on the outside, warm moist air from inside the home can condense and freeze inside the unit, possibly causing damage to the system. Happy shopping ... and stay cool!

Isaac Savage is president of Home Energy Partners, a Building Performance Contracting firm that is located in Asheville, NC. He can be reached at 828 350-1155 or on the web at www.HomeEnergyPartners.com.

Send in your sustainable building and healthy home questions to [e-mail].