We've recently moved to our new townhouse in MA, and it is a second month in a row we're shocked by our electricity bills. We have electric heat pump, it almost never operatres in aux mode (with electric strips), but our bills are close to $700/month. We're suspecting that there is something wrong with insulation. Townhouse has double-pane aluminium sliding windows, as well as aluminium sliding doors to the patio and to the deck. During colder days windows, especially frames, are rather cold, and we feel cold air flow somewhere between frames and sash and somewhere between frames and walls. Before doing anything, I'm wondering what would be more cost-efficient, at least on a medium-term (5-7 years). Does it worth trying caulking/weatherstripping? Or, perhaps, it may solve all the problems? Or I have to invest in reinstalling the frames? Or replace windows entirely, to, say, thermally-broken aluminium ones? Or any other ones (say, combined)? I have a condominium restriction here that new windows have to look like current (aluminium) ones.

Also, walls can be rather cold sometimes. Can it be because of poor windows insulation or I have to consider walls insulation as well? Construction is frame, with brick exterior.

Any suggestion is highly appreciated! We really can't afford $700 monthly electric bills during winter (and possibly during summer).

 

The very first thing to do is to check with your electric utility to see if they offer free or low-cost energy audits. Many utilities do offer these audits and if yours does it is a good starting place.

It is possible that the electric auxiliary heaters in your heat pump are malfunctioning and are on at any time the heat pump is in operation. This alone would send your electric bill through the roof. Do you use a night setback temperature, that is do you turn the thermostat down when you leave the house or go to bed? It has been pretty much proven that doing so with a heat pump will cost more than just maintaining a constant temperature. This is true because in most cases when the temperature is then set for daytime (or occupied) the electric heaters will come on.

How old is the building? This is important because newer buildings were built to stricter energy saving codes. An older building may have significant air leaks and lesser (and poorly installed) insulation. How many outside walls do you have and do you have any units above or below you?

 

Thanks! We'll check regarding energy audits with our town. To check, if electric strips are always on, shall I call for HVAC technician or I can do it by myself? Thermostat shows that it is not AUX heat... Or perhaps, energy auditor can check that?
Yes, we know the trick with maintaining more or less constant temperature during the whole day. We never turn thermostat down...
The building was built in 1977, it is end-unit (three walls), nobody above and below us (we have two floors+attic+walk-out finished basement).

 

Are you the first owners? If so, the builder's warranty should cover you.

 

Just moved in... house built in '77... sounds like this is probably not a new problem.

Aluminum windows- even those that have thermal breaks- are poor insulators and are always cold during winter months. The cold aluminum frame usually means colder glass perimeters and thus colder center of glass temperatures, when compared to wood, vinyl and fiberglass. This is simply because metal is a better conductor of heat... so as you try and heat the house to make it comfortable, aluminum windows are conducting that heat right back out. All windows will do this to a certain extent, so just replacing the windows probably isn't going to cut your electric bill in half.

The best advice I could give is to number one, make sure all your windows are closed and locked. Might sound like a no-brainer, but you would be surprised how many service calls I have made in the last 20+ years in the winter, only to find a window that wasn't 100% shut and locked.

Next, you could inspect if caulking would help anywhere. Take a fireworks punk or an incense stick around the window perimeters and see if there are any obvious drafts that you might be able to narrow down, and it might be that a fine bead of siliconized acrylic painters' caulking on the interior perimeter of the window would help.

Finally, buy and install as many 3M window insulator kits as possible on the interior of your windows. They are fairly inexpensive and if they help they will probably pay for themselves each year. Obviously you won't be able to do your patio doors or other large windows, but anything would help. Thermal blanket curtains are another (more expensive) option, and while they may help with heat loss, they will also cause the window to be even COLDER which can sometimes lead to ice on the windows.

 

Thanks, XSleeper! Don't you know by the chance what is typical payback period for aluminium windows with thermal breaks? You think that difference in electric bill won't justify such investment, considering I already have double-pane windows, don't you?

Regarding closing windows, you're precisely right. Not all the windows can be tightly locked. Hopefully, they need just minor repair. But those, which are close to thermostat are locked. The only problem there is that sliding patio door is close. And, yes, even without incense stick I feel some cold air flow through some windows and patio door. Just by my hand...

Do you think all this can force my electric heat pump to work almost all the day? Just to maintain temperature 68F? That's what is happening now while outside temperature is around 32F(night)-40F(day). Essentially, when heat pump is off the temperature drops pretty quickly.

 

If you purchased aluminum windows with thermal breaks, I do not think it would make a difference. I would try to get those windows closed and locked... do the minor repairs if you can.

 

And I would imagine that if your current aluminum windows are double paned, that they probably have thermal breaks.

 

Even under the best of circumstances it often takes forty years to recover the capital costs for replacement windows. Since you are required to have the aluminum frames I doubt that you would ever have a break even point.