Having a well-insulated home is not only a great way to live toward a greener ideal, but to also save yourself some money on heating and cooling bills.
Increasing the thermal insulation in an existing home doesn’t have to be difficult, and the financial payoff can be substantial in the long run.
This article presents what options you have when improving home insulation, including some small and big changes you can make, as well as how to determine the cost effectiveness of your insulation upgrade.
Why is Insulation Important?
Heat is constantly in movement moving from a warmer to a cooler area, i.e. escaping from within your warm house to the cold outside. Through hot and cool seasons, a significant amount of energy can be transferred through exterior walls, rather than staying in your home to keep you warm or cool.
This heat flow can be reduced with insulation in your walls, giving your home a higher heat flow resistance (also referred to as an R-value). A better R-value means less air is being lost to the outdoors, and the more you save on your energy consumption (and energy bills!).
Consider the following:
Most houses are woefully under insulated
Nearly every home is built with some form of insulation in its exterior walls, but it may not be enough to properly reduce energy loss from your home. The minimum levels of insulation called for in many local building codes aren’t anywhere close to what the U.S. Dept. of Energy recommends for comfort and energy savings today.
For example, many attics have just 6 in. or so of insulation –about R-19. Current recommendations for attic insulation in northern parts of the U.S. are R-49 to R-60.
According to the World Business Council for Sustainable Development, buildings account for 40% of global energy consumption. Clearly, the potential for energy savings through better insulation is huge.
Reducing air leakage and increasing insulation levels results in major energy savings
By sealing air leaks in a typical older house and upgrading insulation levels in the attic and basement (the two most accessible areas for adding insulation), it’s possible to cut heating and cooling costs by 30% or more.
The environmental impact of these savings is significant: fewer carbon emissions from furnaces, boilers and electrical power plants that burn fossil fuels.
Insulation is affordable and accessible
While a solar PV system might easily cost $30,000 or more to install, the cost to upgrade attic and basement insulation in a typical house will probably be $6,000 or less. An insulation upgrade pays for itself in a matter of years.
Nearly any building can be a strong candidate for an insulation upgrade. And insulation materials are widely available no matter where you live.
Insulation is a “once-and-done” improvement
Insulation will last for the life of the house, and it won’t ever wear out or need maintenance. When the right insulation is installed in the right way, it will perform just as well in 50 years as it does right after installation.
Insulation hasn’t been outsourced
All the major types of insulation used today (fiberglass, cellulose, rigid foam, spray foam) are made in the U.S.A. Producing and installing these products means jobs and job security for many thousands of Americans.
Is there anything greener than recycled newspaper?
Cellulose insulation –which can be blown into attics and wall cavities—is made from discarded newspaper. So you’re taking a waste material and converting it into an affordable, energy-saving material. That’s what you might call super-green.
Fiberglass insulation contains up to 30% recycled content, and you can buy “batt-style” insulation made from recycled cotton fiber.
Other eco-friendly insulation options include wool insulation, cellulose insulation, and even recycled denim.
Small Changes You Can Make at Home
Just a few changes and improvements can make a difference to your home.
You may love your home’s windows, but you might love them less when you realize that they raise your heating and cooling bill by 10 to 25% percent every summer and winter.
If you have aluminium windows then you can add draught excluders for better insulation in your home.
You can also apply window film to the interior of your windows. Window film reduces the amount of light and heat allowed into the house through the windows. Homes with low emission window film reduce the amount of heat allowed into the home by 75%.
White blinds, curtains, or weather stripping can be used to increase the insulation of your windows, and can be customized to fit in well with most home décors. If you do not plan on insulating all your windows, you should focus on your home’s south facing windows
Heat can also escape through door gaps, especially at the bottom of doors. Bottom door brush draught excluders are simple to use, discrete, and effective at preventing heat loss. The door draught stoppers made of material are more fun to look at, but can get in the way a bit.
Plants Outside the House
Placing plants and trees in the right areas will create natural shade that will reduce the air temperature around your home by 3-6 degrees. Between the lower temperature, the shade produced by plants, energy loss can be reduced by 25% in your home from plants.
Plants should be placed on the south and west sides of your home. This position will reduce heat gain in the summer while allowing your home to continue to gain heat from the sun in winter.
Deciduous trees will provide shade in the winter and allow your home to receive the benefit of heat in the winter. They should be planted at least 10 feet from your home to prevent foundation damage as the roots spread.
Climbing vines can be allowed to grow up a lattice or trellis to shade windows and offer extra wall insulation. Vines should not be planted directly against homes with wood or composite siding because it will trap moisture and cause rot. It must also be noted that there are rare cases where vines will chip brick and cause structural damage to a building due to excessive weight. If you plant vines, you should carefully monitor them.
The following suggestions are more than a quick DIY project, but the pay-off is substantially more as well.
As heat rises, one of the primary “hotspots” for it to escape is through your roof. The traditional insulation methods for an attic are loose-fill and batt insulation.
Before choosing one of these home insulation types, the attic must first be air sealed, meaning using a tightly constructed box to cover fan housings on the attic side of a duct and covering openings such as dropped ceilings, soffits, and bulkheads with plywood and sealing them towards the attic side of the ceiling.
Loose-fill insulation is cheaper than batt, and – if done right – loose-fill can provide better coverage.
If you have vermiculite insulation in your attic, there’s a danger of it containing asbestos. Do not disturb it and instead hire an insulation contractor to handle it.
Loose fill is generally blown into the attic above the ceiling joists by an expert, while batts, which are mineral wool fibre sheets, can be placed in a criss-cross pattern between the joists yourself, if you feel up to it.
Wall insulation differs between wood frame and solid brick frame walls. Wood frame wall insulation uses loose fill or sprayed foam, which is blown into the cavity of the wall via holes drilled into the drywall or siding.
As a cavity of a solid brick wall is often 25 mm and therefore too small a fill to gain any insulation benefits, a professional must create a cavity. A new cavity wall is built on the interior side of the wall while board stock and new siding are applied to the exterior of the wall.
Basement insulation is advantageous but also a bit controversial as there are many factors that influence it. The energy savings and cost savings are dependent on the local climate and the type of heating system you have.
Once you’ve checked if insulating your basement is the right thing for you and your home, you can then decide between wall or ceiling insulation. Wall insulation is easier and more common, and includes rigid insulation, like extruded polystyrene or rigid fibreglass being installed to the exterior of the walls.
Ceiling insulation in an interior insulation, and can be costly depending on which material you opt to work with.
Calculating Your Energy Savings
For most homeowners, installing new insulation is all about reducing utility bills and saving money in the long run, though it can also be about comfort and environmental awareness.
But how do you calculate the energy savings of a particular insulation upgrade? How can you actually calculate the return on investment of your energy saving upgrades?
It’s certainly not easy to calculate the energy savings of new insulation. Because your energy usage may fluctuate over the year, as well as year to year, it can be difficult to get a percentage estimate in terms of energy savings.
If you’re insulating a home that has little to no insulation, you will certainly notice major reductions in energy costs – approximately 25% – 30% after insulating an attic and 30 – 35% after insulating the walls. You can use these rough numbers to estimate the cost savings you would experience after installing installation.
However, every house and its current level of insulation is unique, so these numbers can vary greatly depending on your home, as well as the quality of the insulation installed on your home.
While it may be difficult to get a specific number in terms of energy savings before installing insulation, you can get a better sense of the energy savings of your insulation install after you have some utility bills post-insulation to compare.
Comparing Current Energy Usage with Old Utility Bills
The first step to calculating your energy savings is to take a look at your utility bill, and find out how much heat you’ve used in the year prior to installing the insulation. All of the heat you used last year had to exit your house somehow. It may have exited through the roof, through windows, through walls, doors, etc.
Once you’ve had your insulation for a year, you can compare your previous year’s consumption with your most recent year’s consumption to get a rough sense of the energy savings you experienced by installing new insulation.
This is certainly easier for those with gas bills, where all of your gas consumption will generally go towards heating (and perhaps the water heater). At this point, you could take the total cost of the insulation installation and divide it by the difference between the cost of the previous year’s energy consumption and the most recent year’s energy consumption to find the number of years it will take to start gaining a return on your investment.
The method above might not work as well for those with electric heating. While it’s certainly more difficult to get a base load to compare with if you have electric heating, it’s certainly possible to get an estimate. For those with electric heating, the best way to determine the amount of energy consumed from heat is to compare your electricity bills during the colder months with your electricity bills from the warmer months of the year. By comparing the differences in energy usage with the local temperature, you can get a rough estimate of the percentage of your electric bill that goes towards heat.
By comparing the warm/cold months during the prior year to the year after you installed insulation, you can get a rough estimate of your energy savings. Keep in mind however, that the comparing and testing method will only give you relatively accurate numbers if you haven’t made other changes to your heating/energy system. If you’ve installed electric underfloor heating or had solar panel installers overhaul your energy system, then it will be extremely difficult – if not impossible – to accurately determine the energy savings of your insulation.
Of course, many homeowners want to estimate their energy savings prior to making the decision to install insulation. Unfortunately, there is no exact way to do this, other than taking the average cost-savings for specific installation areas and applying it to your home. Additionally, you could request an audit from an energy auditor in order to get an estimate of future cost-savings. While this estimate could be fairly accurate, this estimate would simply be an educated guess based on experience.
Should You Install Insulation?
In general, good insulation will pay for itself after approximately 5-9 years, though of course this will vary from home to home.
Either way, by upgrading the insulation in your home, you’ll experience the comfort of an evenly heated home, and the knowledge that you’re doing your part to reduce your carbon footprint.
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Header photo byJeffrey Bell via Flickr creative commons license