Illustration based on modified EnergyStar.gov image

Residential heating requires about 55% of residential energy consumption.  Natural gas and fuel oil are almost always used for heating, and in some regions of the country, electricity is a major source of heat, either through heat pump technology or direct heating.  The energy consumed in heating is a function of the thermostat settings, the external temperatures in the region, the type of heating equipment installed, and the insulating quality of the space you are heating.  This article will discuss a variety of methods to reduce your heating costs that generally can be accomplished quickly and at a low cost.  In last week’s article, we suggested that a 20% reduction in energy consumption might be a good target for residential and commercial energy, and  improving heating efficiency is a major factor in achieving that goal . 

The chart below illustrates the residential energy consumption across the four major U.S. geographical regions (2005 was the most recent year with detailed regional data for energy consumption). 

The table below provides a more detailed breakout of the electricity used in each of the four regions.  It shows that the heating requirements in the northeast are significantly higher than the other regions.  Likewise the cooling requirements in the south are higher than the other regions.

The table below shows the cost of energy in various regions of the U.S. in 2005 and the costs per Btu of energy for the three most predominant forms of heating.  Natural gas provides the least  expensive heat source from fossil fuels (even with an 80% efficiency factor), and direct heating with electricity is the most expensive.

Two important principles of heat and energy:

1. Heat flow (gain or loss) is proportional to the temperature difference between hot and cold environments  (e.g. indoor room temperature versus outdoor temperature).
2. There is an efficiency loss converting fossil fuel energy to heat.  It always takes more Btu’s of energy to replace the Btu’s of heat you have lost.

Keeping these in mind will help you understand the basics of conserving energy in the following examples.  A quick look at your monthly or yearly energy costs will allow you to determine your savings for many of the cost saving measures discussed below.

Opportunities to save energy: 

Many of the following opportunities can be implemented quickly. 

Thermostat Temperature Settings:

The savings obtainable from a small reduction in temperature set point can be significant (remember points 1 & 2 above).  If you are operating at a temperature set point of 70°F in your home when the outside temperature is 30°F, the temperature differential is 40°F.  Reducing the inside temperature to 66°F will result in a reduced heating requirement of 4°F.  This will result in a 4ºF / 40°F = 10% reduction in heat requirements.

For a typical heating efficiency of 80%, it would have taken 12% more energy to deliver that 10% heat (10% reduction / 80% efficiency = 12% energy required to realize 10% heat). 

Programmable Thermostats:

Programmable thermostats allow the user to set different temperatures during the course of the day and for each different day of the week.  This allows for the automatic control of temperatures without the need for constant adjustment.  Let’s look at a simple example of a home where the thermostat is constantly maintained at 70°F, with an outside temperature of 30°F.  If that same home had a programmable thermostat set to lower the temperature to 55°F during the sleeping hours, 70°F from 5am to 8am, 55°F between 8am to 4pm (when the family is working and at school), and 70°F from 4pm to 9pm the heating savings would be approximately 15%.

Programmable thermostats are generally battery operated, can be obtained at any home improvement store, and are easily installed and set by the homeowner. 

Multiple Zone Heating:

Many homes built during the last 20 years incorporate more than 1 heat zone (there is 1 thermostat for each zone, so it’s easy to determine the number of zones in your home).  The multiple zone approach allows you to keep the unused areas of your house at lower temperatures than the highly occupied living areas and can be set independently.  Setting your programmable thermostats accordingly would save additional heating costs.  If your home has multiple zones for heat control, you’ll need a programmable thermostat for each zone that you want to automatically control.

Inspirated Air & Drafts:

Inspirated air is a major source of heat loss.  When cold air is inspirated into a house (at 30F in our example) the air must then be heated to the thermostat setting.

The simple approach to identifying air inspiration is to go around your home and feel for drafts, especially around windows, doors, wall outlets, fireplaces and walls going up to the attic.  Minimizing the inspiration of air can be as simple as replacing weather stripping, caulking air gaps, covering holes, and adding insulation to open wall studs in the attic, but can also be as complicated as replacing windows and doors.

The most comprehensive approach is to hire an energy specialist to come to your home where he/she can establish a slight negative pressure within your house and identify all of the inspiration locations more completely.

Heating savings by reducing air drafts can easily be 10%².

Cleaning:

This simple, but all too often forgotten efficiency improvement can’t be over-emphasized.  If your furnace filters are clogged, or your baseboard heaters are covered with lint, your heat transfer will be restricted and you will require more fuel to achieve the level of heating you desire.  Any equipment used for heating or cooling should be cleaned routinely.

Heating Duct Losses:

Insuring that the heated air (and cooling air during the cooling season) is getting to where you want it to go is another opportunity for significant heating/cooling savings.  Check all of your ducts for tight seals at the joints, re-taping them if necessary.  Check the insulation on the ducts also.  Insulating the ducts will insure that the heated air is delivered to your rooms at a higher temperature than through non-insulated ducts.

However, a word of caution here.  If your ducts run through areas where you want or need heat, insulating them will result in lower temperatures in those areas.  If you insulate ducts in areas under your main floor, make sure your floor is well insulated so the room doesn’t lose heat through the floor.

It has been estimated that duct losses can be a high as 15%.  You probably will not be able to recover all of that loss, but 5% – 10% savings is possible.³

Heating Pipe Losses:

Insulating the hot water pipes in a basement or crawl space is quite easy, and is an inexpensive way to deliver hotter water to your radiators.  It will reduce your fuel costs, but at the expense of lower local temperatures in the spaces where the pipes are located.  Therefore, if you need heat in the areas of the piping or ducting, do not insulate them.

Windows:

Most new homes have gas filled double pane windows, and some homes may have triple pane windows and doors.  These windows and doors provide significantly better insulating properties than the single pane windows in older homes.  If your home still has single pane windows, you should make sure that you also have storm windows installed to help improve the insulating quality.  If that isn’t possible, you can also purchase and install a plastic shrink film to reduce drafts and improve the insulating quality.

Insulation:

Insulation is a key and inexpensive means to reduce heating and cooling costs in all residences.  The recommended insulation thickness will vary depending on the geographical region under consideration.  The map and table below (courtesy of U.S. Energy Information Administration) will give you an idea of the recommended insulation levels for your home.
Installing plenty of insulation during construction is always cost effective.  Installing additional insulation to an existing building ranges from the not too difficult – like attics – to the very difficult – such as finished walls.  If you can easily add insulation, it’s probably cost effective.  If it’s difficult, you should contact a contactor in your area to evaluate the cost benefit of adding insulation.

Aquastat Settings:

Hydronic heat systems work by delivering heated water through pipes to radiators in each room of your house.  The heating of the room is dependent on several factors.

1. The temperature of the water in the radiator.
2. The length of time the radiator is ‘on’.
3. The cleanliness of the radiators – free of dirt, dust and lint.
4. The ability of room air to circulate around the hot water radiator to convect heat into the room. 

In addition to insuring your radiators are clean and that air is free to circulate around them, you may want to reduce the temperature of the aquastat on your boiler.  The hotter the water temperature, the less time the water needs to be circulated through the radiators to achieve your thermostat set point temperature.  However, when the hot water is not circulating, it’s sitting in your boiler losing heat (energy).  Depending on your boiler’s insulation and water capacity, this may be a large or small heat loss.  Generally, the newer and more expensive boilers are more efficient in this regard.

The boiler installation temperature is often set at 180ºF – 190ºF, and you may be able to reduce that to 160ºF-180ºF if you do not live in one of the extremely cold climate areas.  Reducing the set point temperature on the aquastat can be done in small increments, perhaps 5ºF, and running the system for a few days to insure you are comfortable with the heating (the newest and most efficient boilers can measure the outside air temperature continuously and automatically modulate the heating water temperature accordingly).

Summary:

All of the actionable items discussed above can reduce your heating energy consumption with a very low cost of implementation (some also reduce your air conditioning costs in the summer).  Many of them can be completed by homeowners, and in a relatively short time with material available at most home goods retailers. 

In the next article we’ll discuss efficiency improvement possible with the newest technology hot air furnaces, water boiler systems and heat pump technology.  The savings with these new technologies can also be significant, but the equipment and installation costs are substantially higher, and the investment decision is a more difficult. 

¹ courtesy of U.S. Energy Information Administration

² courtesy of U.S. EPA / U.S. DOE

³ courtesy of Home Energy