Archive for the ‘energy efficiency’ category

Insulating Value: Old Cedar Siding vs. New Cement Board

February 18th, 2013

QUESTION:

Last summer, we had our 50-year old cedar siding replaced with fiber cement. They did a good job of caulking around all the windows, however, I am wondering about the insulating properties. I asked to have insulation added, but was talked out of it. They said adding insulation was inconsequential, and not worth the cost. Do you think there is a significant difference in insulating properties between cedar and fiber cement? Our gas bill for period ending Dec ’11 used 60% more therms than last year with 8-degree average lower outside temperature. We did set our thermostat one degree higher.

RALPH

ANSWER:

I023 - Heating Cost vs. R Value - Cold ClimateAs far as insulating value, old cedar siding or new cement board siding would be about equal. It is likely the newer siding provides a little better seal against air infiltration.

The best way to install the cement board siding is to remove the old siding down to the studs and then add a rigid foam board insulation. The joints can be taped, and a house wrap can be added to further limit air infiltration. This allows the siding to be securely fastened to a flat surface and allows more options when working around the windows and doors.

The rigid board insulation does add significantly to the insulation of the exterior wall. I suggest using a 1-inch thick panel of rigid foam. This adds an R-Value of about 5 or 7 and insulates over the edges of all the wall framing studs. The edges of the studs are about 25% of the surface of the exterior wall. Without the foam, they have no insulation.

It sounds like you gas bill is about normal given the very cold and windy weather we have had this winter. Just switching from cedar to cement board should have no impact.

MR. FIX-IT

Frost on One Side of Garage

February 17th, 2013

QUESTION:

We have a new home. With the cold, windy weather, we have noticed frost on the screw heads in the drywall garage ceiling edge. This issue is on the north side; none of the other walls have this problem. The garage is unheated, and the walls/ceiling are insulated. There is also a vapor barrier over the insulation. My husband says cold air is coming through the outside soffit, and there is no way to insulate this. There is also an electrical switch with frost on the screw heads on that wall. What can we do? Should we be concerned?

SHARON

ANSWER:

I014 - Air Bypass at Insulation - OverhangThe problem is caused because the screw heads are colder than the dew point temperature in the garage. In fact, the screw heads are below freezing so the moisture condenses and freezes. You have two solutions – raise the temperature of the screws or reduce the relative humidity in the garage.

Assuming you don’t want to raise the temperature in the garage, you can try to raise the temperature of the screws. I think your husband is correct – cold air is leaking into this wall area, either at penetrations, gaps, or through the roof venting. The cold air blows in and cools the wall.

For the attic venting, you should check above the soffit vents and make sure there are air chutes that direct the ventilation air over the insulation. If it blows into the side of the insulation, it will chill the wall. At times the best solution is to seal the air chute from the top of the wall to the roof deck with spray foam insulation. You want the air flowing over the insulation.

You should also look for any exterior gaps that may need sealing – perhaps around light fixtures, at the lower edge of the siding and around windows and doors. Any penetration in the wall and house wrap is suspect.

You could heat the garage; that would solve the problem, but I don’t suggest that. Lowering the relative humidity in the garage is virtually impossible, however you could sweep out snow and ice that may drop off your car.

MR. FIX-IT

Infrared Quartz Heaters

February 12th, 2013

QUESTION:

What are your feelings about infrared quartz heaters? Which brands have you tested? I have one and it seems to provide all the energy representations made. Is it true that this technology was developed for the space station and utilized in the space shuttles?

BILL

ANSWER:

I have never tested any of the electrical heaters or quartz heaters and can’t comment on any specific brand. But wow, there seems to be a lot of marketing for electrical space heaters these days. I am an engineer who studied some of that thermodynamics and heat transfer stuff in college. If the claims are too good to be true, they are not true.

The fact is, you can’t create or destroy energy; you can just change it from one form to another. Electricity has just so many BTUs per kilowatt hour. You can convert electricity to heat with a cheap electrical resistance heater, a light bulb, or an electrical burner on the stove with the same result and always the same amount of energy.

Because we are all trying to save energy and money, all the marketing for the new space age or high tech electrical heaters sounds great; and we want it to work. But it can’t defy the laws of physics. Any type electrical heater will provide the same amount of energy for the amount of electricity used.

MR. FIX-IT

Furnace fan, to distribute heat throughout the house?

January 31st, 2013

Question:

I have a two-story house with a basement, built in 1952. Is it a good idea to turn the furnace fan on, to distribute the heat throughout the house?

– Marian

Answer:

H014 - Warm Air Furnace Fan and MotorYes and no. If you have a problem with a cool area when heating or a warm area when running the air conditioning, operating the fan continuously will even out the temperatures in your home. The downside is this will cost electrical energy to run the fan and cause some wear and tear on the fan. However, you can run a fan on a newer, high efficiency forced air furnace with an ECM or variable speed motor for little cost – about 1/10 the cost of a typical fan motor. Finally, I think your first step is to have a contractor inspect and adjust your system. At times, duct dampers can be adjusted to correct cold spots and air flow problems. Often you need to make a spring and fall damper adjustment for a two story home.

– Mr. Fix-It

Energy Efficiency Improvements – Where to Start?

August 21st, 2010

QUESTION

I have some funds to do energy efficiency improvements to my old (1950’s) home, but I don’t know where to start. The home is well maintained, but has had no energy improvements. It seems that every contractor has the best product, and there are many claims about huge energy savings. The government rebates and tax credits just seem to complicate the issue. Where do I start?

ANSWER

There is no simple answer. I can outline where to logically start, but I think your home deserves an evaluation and some scientific testing before you start spending.

I suggest you contact Focus on Energy. Their goal is to provide information, resources and financial incentives to help improve energy efficiency in Wisconsin. The state program is well known throughout the country.

I used the Focus on Energy program called “Wisconsin Energy Star Home Program” when I built a new home. They gave advice on construction details, and worked with the builder on energy efficiency. The results were fantastic.

For existing homes like yours, they offer a service to scientifically evaluate your home and the systems in your home at a very reasonable price. Their consultants can test for leaks, review your equipment, and use a computer model to identify the best areas to invest.

Overall, you should look at the easy energy improvements and your old equipment. If you have a furnace that is over 25 years old, put that at the top of the list. If the attic insulation has never been improved over the original three to six inches, that should be high on the list as well. Insulating the top of the basement wall, using low-flow plumbing fixtures, fluorescent lamps, and a set-back thermostat are simple changes with a great payback.

An evaluation by the Focus on Energy is the best first step. They also offer a new interactive website at Ask Focus on Energy. They will answer your questions and refer you to a large database of answers. If you have a unique question, one of the experts can respond.

Saving Energy With Fluorescent Lighting

June 29th, 2010

QUESTION

I am trying to find some info regarding the power usage of fluorescent ballasts. I was told that it takes more electricity to energize a ballast initially than to run the light for a few hours. I don’t know if that’s true with the new rapid-start/electronic ballasts. Is it going to save any energy to turn off office lights for an hour, then turn them back on?

ANSWER

Great question! Most folks don’t realize all the modern changes in fluorescent lighting. The ballasts are now electronic and this dramatically changes performance and efficiency. Remember the days of the old “starters” (the little aluminum can inside the fixture)? Modern fluorescents have a starter built into the ballast. The ballast is used to energize the lamp and start the flow of electrons.

In studies I have read, you should always turn off the lights when they are not needed, even if only for a few minutes. The calculations show that the energy used to start the lamp is saved in a few minutes of operation. The on-off cycles really do not affect the life of the newer florescent lighting. Sometime a “few minutes” can turn into a few hours, so always turn the lights off.