This winter, my dad could no longer manage living alone so we moved him in with us. He ran central air all summer in his old place and he insists he’ll need a window unit in his room here. I explained that he won’t need more than a fan, but he’s not budging. Frankly, he doesn’t ask for much, so do you have any tips on buying the most efficient model?

You bet. The easiest way to make sure you're choosing an energy-efficient window air conditioner is to look for the ENERGY STAR label. Then, compare ENERGY STAR models by looking at their "Energy Efficiency Ratio" or EER. The higher the EER number the more efficient the air conditioner.

Just as important: Make sure that the model is the right size for your father’s room. An oversized air conditioner runs up the electric bill and leaves a room feeling damp and clammy. That’s because an oversized unit quickly cools a room without removing sufficient humidity. You can view a sizing chart by visiting www.efficiencyvermont. com and searching for “Room Air Conditioners. Also at this site, go to the Residential Rebate Center for a list of available rebates on ENERGY STAR qualified air conditioners.

- Bob for The Home Team

With summer coming, my husband and I are starting our annual debate about putting a whole-house fan in the attic hatch. I grew up with one and I think they’re a low-energy way to cool. He thinks they’re wasteful. Can you settle this once and for all?

Before I answer your question, I want to point out that, in many Vermont houses, the need for mechanical cooling can be eliminated or reduced with a few home improvements and some simple cooling techniques. The first step is a comprehensive job of air sealing and properlyinstalled insulation, which also will reduce heating-fuel use in the winter. Then, take low- or zero-energy cooling actions, like creating a cross breeze by opening windows in the cool part of the day (with or without window fans), closing windows before the day heats up, and shutting window coverings to keep out direct sunlight.

Let’s assume, though, that you and your husband have done all these things and you’re still too hot in the summer. In that case, an attic-hatch fan can be an effective way to cool a house by bringing in air through open windows when it’s colder and less humid outdoors than indoors. To be effective, this fan needs to be installed in an attic with a well-sealed floor and sufficient attic venting. Without these elements, a whole-house fan can actually push hot attic air down into the house through unsealed cracks or gaps in the attic floor.

As for energy use, an attichatch fan, like a window fan, can be an energy saver when compared to air conditioning. But the cost of operating an attic-hatch fan is only part of its energy story. By installing this fan, you’ll open a gap between your living space and the attic. So, if you decide to get one, a thorough job of sealing that gap will be needed to avoid increasing your heating costs in the winter. A good start is to have a well-insulated fan and a sealed cover with a motorized opener. If, as can often be the case, you’re unable to thoroughly close the gap made by an attichatch fan, the cost of winter heat loss may make this fan as wasteful as your husband thinks it is.

- Kathleen for The Home Team