Buildings

Hot and Cold

Q: We recently moved into our new home, and we love it except for the fact that we couldn't get it warm enough last winter or cool enough this summer in the family room. Both the builder and the air conditioning contractor say everything is "working fine," but it really gets uncomfortable in there. What can we do?

A: You have three basic choices: 1) learn to live with it, 2) get some help to figure out what the problem is and how to fix it, or 3) spend the next ten years complaining about it and then doing 1 or 2.

Learning to live with it might include staying out of that room when it's too cold or getting a fan to blow air on you when it's too hot. Don't like those ideas? How about installing a hot tub? You can fill it with hot water for the winter and sit in it when you get too cold. In the summer, you can fill it with cold water and cool off.

While this might make an amusing conversation piece, most of us expect a reasonable level of comfort in our home. In trying to figure out the source of the problem, it's helpful to think about whether the problem is with the house, the air conditioning equipment, the air distribution system, or some combination of all three.

The most common problems I see in new houses to create these conditions are poorly installed or missing insulation, major air leakage, large amounts of unshaded west-facing glass or skylights (for overheating problems), and leaky ductwork. If you have cathedral ceilings, the only way to check the ceiling insulation is with an infra-red camera. Even if the insulation was installed properly, you may have a problem if you have recessed light fixtures in the ceiling.

Recently, I was in a house with a beautiful great room measuring about 20' by 36'. There were 20 recessed lights in this one 720 square foot room. Each light is a six-inch can. Unless it is a specially rated fixture (IC — Insulation Contact) there needs to be at least a three inch clearance between the fixture and the insulation. Six inches plus three plus three equals a 12-inch diameter circle with no insulation. A twelve-inch diameter circle equals about three-quarters of square foot. Twenty of them equal nearly sixteen square feet.

So what these folks had was the equivalent of a 4' X 4' area with no insulation. Each can is made of metal, which will conduct heat from the 130 o attic into the room in the summer, from the room into the attic in the winter. Even worse, the can was also a standard fixture, not one of the new airtight ones, so there was a direct air passage from the attic into the room. When we measured the air pressures in the house, we discovered that every time the air conditioning system came on, it created a negative pressure in the great room, effectively sucking hot air from the attic into the room through every light fixture. In the winter, it will suck cold attic air into the room.

This house also had a pull-down attic stairway in the hallway connected to the great room. This was not weather-stripped and had some fiberglass insulation stuffed under the steps. This is an even larger area that was left inadequately insulated and not sealed to prevent air leakage.

The room had a beautiful window wall looking out onto a pond. Unfortunately, the windows faced almost due west, with no solar screen, sun film, coating, or exterior shading device. The mini-blinds helped a little, but by the time the sun hits them, the heat is already in the house. In the winter, this large window area serves as a giant "heat sucker," pulling heat from the house out into the cold night air.

Our investigation also turned up significant duct leakage throughout the house, but even more in the ducts serving this room. Essentially, a large part of the air the owners were paying good money to heat or cool was being lost into the attic.

The air-conditioning contractor won the job by submitting the low bid. One of the ways he is able to bid low is to depend on his experience and rules of thumb to size the systems, rather than actually analyzing the house. In this case, even though he typically oversized everything (which results in a lot of other problems), the system couldn't keep up with the extra loads created by the lights, the attic hatch, the windows, and the duct leaks.

The good news is that most of the problems in this house can be fixed for a moderate cost. The sad part is that it would have been much less expensive to do it right the first time.