Best Practices to Build Energy Efficient Crawl Spaces

Contents

• Introduction
• 1. Provide adequate drainage
• 2. Control ground moisture with a vapor barrier
• 3. Chose the proper insulation method.
• 4. Chose the right insulation type
• 5. Control outside air and moisture infiltration by air sealing the crawl space.
• 6. Control moisture from condensation with a dehumidifier
• Sources and Information

Introduction

Crawl Space insulation is one of the hottest topics in home improvement and home efficiency these days.

Homeowners are actively seeking for the best return for their investment, whether they are struggling to diminish the impact of soaring fuel prices in their lives, or racing to cash in government incentives and the Federal Tax Credit for Home Energy Efficiency.

As they try to decrease their home’s energy consumption, lower their utility bills and improve comfort, insulating the home’s foundation is becoming a top priority – especially for homes built on vented crawl spaces that have dirt floors.

Justifiably so: A dirt-floored, vented crawl space is a huge energy waster. For a home with ductwork running in a vented crawl space, HVAC system efficiency can be reduced by as much as 50%.

According to Advanced Energy, energy loss in these homes is so substantial that they might as well ignore all other attempts to save money and energy until the crawl space problem is solved.

That said, it is necessary to understand that effective crawl space insulation can not be achieved without proper measures to control moisture in that environment, or without using waterproof materials to to seal out and remove the moisture.

The following is a step-by-step guide to proper crawl space insulation.

1. Provide adequate drainage

• Grade the terrain around the house to slope away from the foundation. Keep gutters clean or install them if the house has none.
• Extend the downspouts at least eight feet (the typical backfilled area) away from the house.
• Plants and bushes that need regular watering should be kept away from the foundation, and care must be taken to prevent hoses and outdoor faucets from leaking.

Sometimes, the above measures will not completely keep the water from entering the crawl space. Interior drainage pipe combined with a sump pump might be recommended in these cases, as well as the use of drainage mats underneath the ground cover.

Drainage mats, as shown in the picture to the right, will keep water from getting in and provide a desirable thermal break as well.

The ill effects of a vented, dirt crawl space can be felt in many other ways besides high heating and cooling costs. Cold drafts come through the floor in the winter, while uncomfortable indoor humidity enters the house during the summer. Moist atmosphere is unhealthy and destructive – a place where mold thrives and spreads.

2. Control ground moisture with a vapor barrier

A crawl space with adequate drainage will still have moisture problems, coming from two major sources:

the ground and the outside air.

Ground water will evaporate into a dirt-floored crawl space and soak the joists and wooden structures. It will also infiltrate concrete walls and floor causing them to be damp most of the time. It is not possible to effectively insulate a craw space without eliminating these major moisture sources.

Most building codes and contractors will recommend a waterproof ground cover, which will keep some of the ground water from evaporating into the crawl, but will not address the water that seeps through the walls.

To completely control moisture in the crawl space, both the floor and the walls should be lined with a vapor barrier that completely isolates the area from ground and wall moisture. This process is commonly called crawl space encapsulation.

In warmer areas, the entire space, including the walls, can be lined or encapsulated with a flexible poly sheet vapor barrier and, if the space is properly air sealed and conditioned, there will be no need to add insulation.

Drainage mats also provide a thermal break under the vapor barrier.

We will examine this process a bit further in this article, when discussing different insulation approaches.

While the norm is to use generic 6mil poly sheet to line crawl space , better, long-lasting results can be obtained by using a 10mil or 20mil crawl space vapor barrier instead.

These liners were developed specifically for this application. If mechanically fastened to the walls, a sturdier liner will not rip as easily when people crawl on it, during inspections and maintenance visits.

3. Chose the proper insulation method.

The most popular and widespread method of crawl space insulation - applying fiberglass insulation bats between the floor joists of a vented crawl space – is also the main cause of most crawl space mold disasters.

Fiberglass soaks moisture like a sponge, and in contact with water it sags, also supporting mold growth on its paper facing. To make matters worse, damp fiberglass loses it is R-Value, becoming useless as insulation, and as it sags, it opens holes in the insulation blanket, allowing the air to leak into the living area.

The U.S. Department of Energy recommends that rigid foam board insulation be used on the craw space walls. Rigid foam is waterproof, does not absorb moisture, and will not support mold growth, so it’s an excellent choice in moist areas like basements and crawl spaces. It’s also recommended to install insulation against foundation walls rather than between floor joists, because this extends the “building envelope” to encompass features like ductwork, water heaters and HVAC equipment.

Advantages of insulating the wall, rather than the floor include:

• Although foam board is more expensive than fiberglass bats, less insulation is required for the walls.
• The crawl space becomes part  of the building envelope of the house, so there is no need to insulate pipes and ductwork running beneath the house for energy efficiency or protection against freezing.
• Air sealing between the house and crawlspace is less critical.

The boards should be attached straight against the walls, using the proper adhesives. The ground vapor barrier should overlap the board at the base and taped over with mastic tape.

A protective membrane should cover the the top of the block wall to allow for termite protection and it should also overlap the board a few inches as well. Professionally developed crawl space encapsulation systems include a transparent cap instead of this protective membrane, to facilitate termite inspections.

It is not always necessary to insulate the floors, specially if you are using a drainage mat, which provides a thermal break.

In colder climates, a lower R-Value foam bord can be placed between the mat and the vapor barrier.

4. Chose the right insulation type

Fiberglass insulation:

As we mentioned before, fiberglass insulation is quite popular because it is the most inexpensive insulation

material available. However, it is the worst possible choice for a crawl space, because it absorbs moisture and favors mold growth.

Cellulose Insulation:

Although modern cellulose insulation is chemically treated to be mold resistant and handle moisture better than fiberglass it is still made with organic materials and there is not enough data to support that it can withstand chronic moisture conditions.

Closed Cell Spray Foam Insulation:

Closed cell spray foam, when properly applied is an excellent choice for crawl spaces. It expands after application, air sealing gaps and fitting snugly around pipes, wiring, ducts and fixtures. When incorrectly applied, however, it can lead to problems.

The insulation blanket should, for example, end a few inches before the top of the wall, and include a protective, removable protective membrane, or cap, to allow for termite inspection.

When applied on wood, installers should make sure that the wood is dry and healthy (mold free), otherwise you will seal the problem but the mold and rot can still cause the wood to decay under the insulation layer.

Another problem with spray foam insulation is price. It costs from 2 to 3 times more than any other type of

insulation in the market.

Rigid Foam Board Insulation

The U.S. Department of Energy recommends using rigid foam board to insulate crawl spaces. Less expensive than spray foam, it is impervious to water, inorganic and non absorbent.

There are basically 3 types of foam board insulation with R-Values ranging from 3.8 to 8.7 per inch:  Extruded polystyrene (XPS) , Expanded Polystyrene (EPS) and Polyurethane.

Foam board comes in different thicknesses, and board sizes are typically 2x8ft. or 4x8ft. Polyurethane foam has the highest R-Value per inch.

To find out which is the best R-Value for the area you live in, refer to the DOE insulation guidelines found in this map (zip file). Insulation boards are attached directly to the wall with mechanical fasteners, adhesives or a combination of both.

A vapor barrier, lining the floor, usually overlaps the base of the board a few inches, and is secured and sealed onto it with mastic tape. Any gaps and holes are then sealed with tape, caulk or spray foam.

For improved energy savings, a lower R-Value foam board, can be placed under the ground cover or in between the liner and the drainage mat.

5. Control outside air and moisture infiltration by air sealing the crawl space.

On the warmer days, the outside air, if allowed to enter the crawl space through the vents, will cool down.

As it does, relative humidity levels will increase 2.2% for each degree that the outside air is cooled.

A temperature difference of only 10 degrees will cause an increase of over 20% in RH once the outside air enters the crawl space. When the RH levels in the crawl space rise to or above 60%, mold is likely to develop. And that happens quite often during summer.

During the winter, RH levels are not much of a concern, but if you have ducts and pipes in the crawl, you can have some condensation issues. The biggest problem during cold weather is the infiltration of cold air into the living space. Often homeowners complain of cold drafts that can be felt coming from the floors above a crawl space.

This is why air sealing is fundamental, if the goal is to increase energy efficiency. Crawl space insulation

without air sealing is not as effective. The encapsulated crawl space should be thoroughly air sealed and the access to the crawl space should be through an outside entry that can be effectively air-sealed when not in use.

Note: in areas in which radon is a concern, such a crawl space encapsulation system acts as a passive mitigation system, but tests should be conducted to determine if there is the need for an additional radon mitigation system, which can be easily installed to work with the vapor barrier.

6. Control moisture from condensation with a dehumidifier

With the space is completely isolated from ground and outside air, some condensation may still occur due to temperature differences between the crawl space and its surroundings. That moisture should be addressed with a crawl space dehumidifier. A dehumidifier will draw any moisture present in the air before condensation happens.

Good crawl space dehumidifiers are energy efficient and require little maintenance, as they monitor RH levels, turn on and off as needed, and empty the collected moisture into the sump pit.

An encapsulated and properly insulated crawl space can significantly decrease a home’s energy consumption, protect its structural integrity and improve the lives of its inhabitants.

Crawl space insulation is one of the home improvements that bring the best results and the most savings per each dollar invested.

Good dehumidifiers for crawl spaces, discharge the collected moisture into the sump pit , saving homeowners the trouble of emptying the trays regularly.

Sources and Information

Advanced Energy

http://www.crawlspaces.org

US. Department of Energy – Energy Efficiency and Renewable Energy

Crawl Space Best Practices – Consider the Crawl

Crawl Space Insulation

US DOE – Energy Savers

Insulation and Air Sealing

Forest Products Laboratory

Crawl Space Ventilation

SouthFace.Org

Radon Resistant Construction

Crawlspace Insulation

RLC Engineering

The Fallacies of Venting Crawl Spaces – Craig DeWitt, PhD, PE

Best of Building Science

Closed Crawl Spaces do Double Duty

Building Science Corp

New Light in Crawl Spaces

Basement Systems Inc

Crawl Space Learning Center

Doctor Energy Saver

Crawl Space Insulation

Choosing the right type of insulation for every room in the house.

Beefing up a home’s insulation is always a great way to save energy. Insulation slows the transfer of heat, keeping the living area of your home comfortable and your HVAC system from working too hard.Yet, according to the Chicago Tribune more than 60 percent of U.S. homes are underinsulated, especially when it comes to attics and foundations.

Before you tackle a home insulation job, however, you need to keep in mind that not all insulation materialsare created equal, and the success of any insulation retrofit depends largely on the choice of materials and the quality of the installation work.

In other words, consider the room or space you want to insulate. An attic that is not used, for example, can be filled with blown-in insulation, while one that will be used as living space or storage, often needs a different type of insulation. An insulation type that works above grade, can be a disastrous choice for your basement, due to moisture and mold concerns.

Choosing wisely will allow you to meet your insulation needs, within your budget, and provide you with the comfort and savings you expect.

Below are the main factors to be considered when choosing the right insulation type:

R-Value

“R” stands for resistance to heat transfer, so the higher the R-Value, the better the insulation capability. The R-value per inch of a given insulation material will determine how thick the insulation blanket needs to be to achieve the recommended total R-Value of insulation for the area.

Some types of polyurethane rigid foam board insulation, for example, have an R-Value of over 7 per inch, while fiberglass batt insulation is rated at just R- 3.8 per inch.  You would need a thicker layer of fiberglass to achieve the R- 25 insulation value recommended for floor insulation by the U.S .Department of Energy for many areas of the country.

The map below shows the U.S. DOE R-Value recommendations for different areas of the country.

 Fire Resistance Rating & Combustion Safety

The behavior of insulation materials in the presence of fire is a crucial to ensure success and safety of the application. Some insulation materials are highly combustible and can’t be used without being covered with a fire-resistant material like gypsum board. Other types of insulation like cellulose are treated with fire-retardant chemicals, and don’t require a protective covering. ,

Also, some materials, when in combustion, release toxic fumes so building codes forbid using them without a fire retardant cover as well, especially in basements, where these toxic fumes can reach lethal concentrations rather quickly.

Behavior when in contact with moisture

.Bill Loden, a Madison, Ala., home inspector, tells Consumer Reports that “If there are 10 things that can go wrong with a house, 15 of them have to do with water”, and he is right on the money.When choosing insulation types, especially for basement and crawl space areas where moisture is present, it’s important to select insulation that isn’t affected by water. Fiberglass batt insulation is a bad choice for moist areas because it can absorb moisture and lose its R-value. Damp fiberglass also compresses and sags, creating voids where no insulation is present. The paper facing used on some fiberglass batts encourages the growth of mold when moisture is present. All of these factors make fiberglass unsuitable for basements and crawl spaces.

Rigid Foam board is recommended for basements, crawl spaces and any moisture prone areas, by the U.S. Department of Energy because it is virtually impervious to water.

Application Method.

Application details can also determine the suitability of insulation for a particular use.

Fiberglass batts work well above grade, installed between studs or joists. A skillful installer and can cut and fit batts around plumbing and wires to keep the insulation layer continuous. This fitting work is essential to eliminate insulation voids that will waste energy.

Rigid foam board insulation also needs to be cut in order to fit around wires, plumbing pipes and other objects. This typically results in voids or gaps that are filled by applying expanding spray foam –a material that seals as well as insulates.

Blown-in insulation, be it cellulose or lose-fill fiberglass, can be used to fill in small spaces, cavities or close insulation gaps inside walls.

Spray Foam, although more expensive, is perfect to insulate tricky surfaces like sill plates, and around pipes, wires and fixtures, because it sticks to the surface. Its expanding capabilities also make it ideal to air seal and close gaps left by other insulation types.It is good to keep in mind that with the exception of spray foam insulation, insulation materials slow heat transfer but can’t stop energy loss through air leakage.  The best insulation work in the world will not help you save much if your house hasn’t been properly air-sealed.

If you are serious about making your home energy efficient, call in an energy conservation expert who can  test the home for air leakage, then recommend a whole-house strategy that combines air-sealing with additional insulation.

According to the U.S. Department of Energy, homeowners can reduce their homes’ heating and cooling costs by as much as 20 percent through proper insulation and air sealing techniques.

Committing to a more energy efficient lifestyle is one of the greenest things you can do for the environment. Every little step helps!

It’s time to think GLOBALLY & act LOCALLY to help preserve our planet

by Tim Snyder

Some history buffs might argue that the environmental movement began in 1962 with the publication of “Silent Spring,” Rachel Carson’s bestselling book exposing the ecological hazards posed by pesticides and other chemicals. But environmentalism truly became a global issue 8 years later with the first-ever Earth Day demonstrations. This year, Earth Day (April 22) will be celebrated by a billion people around the world.

Earth Day stands alone as the only event to rise above the countless political, economic, religious and cultural allegiances that prevail around the world. Regardless of our ethnicity, sex, geographic location, economic status or religious affiliation, we all share a single planet. More than ever, this spinning orb needs our help to maintain clean air, potable water and healthy ecosystems. If you haven’t decided how make an Earth Day difference yet, here are a few actions to consider:

Get the light right.
The environmental impact of LED (light-emitting diode) technology is HUGE. If our country converted to LED lights, we’d cut electrical use for lighting by 33% and decrease annual greenhouse gas emissions by over 650 million tons. LED lights are still too expensive to totally replace incandescent and compact fluorescent lights (CFLs). But buying these lights incrementally is a good idea. Since an LED light can easily last for 25,000 hours, it provides many years of financial and environmental benefits. And unlike CFLs, LED lights contain no toxic mercury.

Schedule a home energy audit.
Comprehensive energy audits like those performed by Dr. Energy Saver provide you with a complete master plan for energy savings. This “whole-house” assessment includes specific recommendations on a wide range of energy-saving upgrades. You’ll also learn what upgrades to perform first, to ensure the best return on your “green” investment. Cutting your home’s energy consumption doesn’t just help the environment by reducing carbon emissions; it reduces your monthly utility costs.

Cut down on electricity-wasting “phantom loads.”
You don’t have to wait for an energy audit to stop wasting electricity because of phantom loads. Cut this unnecessary electricity use by COMPLETELY turning off computers, TVs, printers and battery chargers instead of allowing them to consume power in “sleep” mode.

Adopt a local cause.
With a little creative thinking, you can take on a challenge that promotes sustainability and environmental quality in your neighborhood. Here are a few ideas:

• Promote two-wheel travel. Drum up support for bicycle-friendly features like bike lanes, bike paths or bicycle stands.
• Jump-start backyard vegetable gardens. Ask your local hardware store to start a “grow your own” program by donating free seeds when people buy gardening supplies.
• Put plastic in its place. Enlist local businesses and citizens to stop using disposable plastic shopping bags that pollute oceans, kill wildlife and consume petroleum products.
• Start a green blog. Talk up environmental issues, preferably on a website (see Patch.com) devoted to local issues & events.
• Hit the trail. Taking more walks and hikes improves your health as well as your environmental awareness. Aim for an “Earth Day” frame of mind: gratitude for the great outdoors, and a desire to protect our incredible (and fragile) planet.

What does your home have to do with world news?

by Tim Snyder

“Look, honey! Our house is on TV. We made the 6:00 news!”

OK, I’ll ‘fess up. I used the exclamation above to get your attention. We both know that the chances of seeing our house in a news broadcast are pretty slim. But now that we’ve started this conversation, I’d like a chance to prove that my bogus headline has a lot more truth to it than you may believe.

Let’s start with some events that really ARE in the news –like the political instability that’s sweeping through the Middle East. Major oil-producing countries in this part of the world are in the throes of revolution. Whether these upheavals will have positive or negative results remains to be seen. But what we know right now is that petroleum production and transport could easily be disrupted in major ways. The embargo on Iranian oil complicates matters further, as does China’s growing demand for fossil fuels to power its fast-growing economy. Even the promise of abundant (and cheap) natural gas supplies from our own shale deposits is far from a sure thing, because hydraulic fracturing (“fracking”) has been associated with water pollution and possible earthquake activity.

Today all fossil fuels are commodities in a highly competitive global marketplace. When a supply source in one region suddenly diminishes or gets cut off, the ripple effect is quickly felt on the other side of the world, presenting us with the double whammy of higher prices and more limited supplies. This explains the connection between our houses and the ongoing Arab Spring that’s receiving so much news coverage. The volatility of energy resources around the world is leading many homeowners here in the U.S. to place a high priority on home energy efficiency.

The good news about the uncertainty of energy resources is that we can do something about it, one home at a time. It’s a simple formula: Making your home more energy efficient means you’ll have less financial hardship when energy costs increase. Energy-saving upgrades like air sealing and additional insulation are especially attractive because you only pay for them once; they never require maintenance and they never wear out. These two improvements alone can cut your heating and cooling costs by as much as 40%.

Investing in home energy savings starts paying off right away; you don’t have to wait for the next oil spill or oil embargo. In addition to having more money in the bank, your more efficient home will also be more comfortable. So what are you waiting for? Your home will probably be in the news again tonight.

by Tim Snyder

7 reasons NOT to insulate with fiberglass

Fiberglass insulation (and its main mascot, the Pink Panther™ trademarked by the Owens Corning Corp.) has dominated the home insulation market for generations. Since its invention by Owens Corning in 1938, fiberglass has been the go-to material for insulating just about any building assembly. Glass fibers have been made into batts, blankets and loose-fill insulation for use in walls, floors, ceilings and attics.

But this long run as the dominant insulation material may be coming to an end. Interest in energy efficiency continues to grow due to rising energy prices and the popularity of “greener” living. As a result, building scientists, insulation contractors and consumers are finding alternative insulation materials that outperform fiberglass in significant ways.

Fiberglass is still less expensive than most other types of home insulation, and will probably retain its price leader status for some time to come. But poor performance compared to other types of insulation shouldn’t be ignored. Whether you’re choosing insulation for a new house or upgrading existing insulation levels to increase interior comfort and decrease utility costs, here are 7 reasons why fiberglass insulation might not be the best choice.

1. Low numbers. The universal measure for insulation is R-value, and fiberglass insulation scores pretty low on the R-value scale when compared to other types of home insulation. For example, a standard 3½-in.-thick fiberglass batt designed to fill a 2×4 wall provides just R-11 of insulation value. Filling the same space with spray polyurethane foam (SPF) achieves R-21.

2. Installation errors. One reason for the popularity of fiberglass insulation has been easy installation. But research by building scientists has shown that it’s nearly impossible to install fiberglass batts perfectly, and installation errors are costly in terms of energy performance. A void (missing insulation) that represents just 5% of the total insulated area for a wall assembly can diminish the wall’s insulating performance by as much as 50%.

3. Mold & moisture problems. Fiberglass insulation (especially batts faced with kraft paper) can absorb and hold moisture. While this won’t degrade the glass fibers, it dramatically diminishes R-value, while also encouraging mold and rot in surrounding building materials. Mold grows easily and abundantly on paper-faced fiberglass batts, and on wood and wallboard in walls that remain damp.

4. Air movement. Fiberglass insulation can slow heat transfer by conduction, but it can’t stop heat transfer by air movement or convection. The numerous gaps, cracks and openings in the “building envelope” allow conditioned inside air to escape (exfiltration) and outside air to enter the building (infiltration). To ensure maximum R-value with fiberglass insulation, these leaks must be sealed in a separate air-sealing step.

5. Bad below grade. Over the years, fiberglass batt insulation was used extensively to insulate framed walls in finished basements and to insulate crawl space ceilings. It is no longer recommended for these uses because of the moisture-related problems explained in #3, above.

6. Stellar competition. Most of the limitations of fiberglass have been overcome by other types of insulation. Closed-cell spray foam and rigid foam are two insulation materials that don’t absorb moisture and are preferred for use in basements and crawl spaces. What’s more, these materials positively seal the spaces they insulate, significantly diminishing energy losses due to air infiltration and exfiltration.

7. Not so green. Yes, all insulation has “green” value because it helps to save energy and reduce our consumption of fossil fuels. But fiberglass insulation isn’t nearly as green as cellulose insulation, the other “fluffy” insulation option. Cellulose insulation contains about 85% recycled content and doesn’t require a lot of energy to manufacture. Fiberglass insulation typically contains 20%-30% recycled glass, and requires furnace temperatures in the 2500degrees F range –a very energy-intensive process.

by Tim Snyder

We’re all caught up in the excitement, celebration, anticipation and (let’s be honest) exhaustion of the Holiday Season. It’s challenging to fill in the blanks on your gift list and manage a schedule that crams work, parties and holiday travel into such a short span of time. No wonder so many of us breathe a sigh of relief when January 1st rolls around.

Don’t be angry with me for suggesting one more gift. Look, the recipient isn’t expecting anything, and this present can actually be given at any time over the next year. All that’s required right now is a commitment to bestow the gift –perhaps in the form of a reminder note pinned to a bulletin board or posted on your refrigerator door. The cool thing about this gift is that it will pay for itself many times over in the coming years. You and other family members will benefit greatly, and by following through on this commitment, you’ll be setting an example for others to follow.

The gift I’m talking about is a home energy audit for your house. Performed by a certified home energy analyst, this basement-to-attic assessment has the thoroughness of a tax audit, but instead quantifies all the ways that your house uses and loses energy. The audit compares your home’s insulation levels with those recommended by the U.S. Dept. of Energy. It establishes the efficiency levels of major energy-consuming appliances like your furnace and water heater, benchmarking them against highly efficient ENERGY STAR® models.

A master plan for saving energy

Just as a tax audit identifies your financial weak points, an energy audit reveals the areas where your house is underperforming in terms of energy efficiency. You’re likely to discover that your utility costs are hundreds of dollars more per year than they should be due to inadequate insulation levels and excessive air leakage (common problems, according to DOE findings). Other common energy problems include poorly insulated basements and crawl spaces, missing insulation on hot water lines, and older water heaters that consume excessive amounts of electricity, propane or natural gas.

Some energy audits are more thorough and more useful than others, so it’s important to shop around. The end result you’re looking for is a master plan to make your home more energy efficient. A good energy audit tells you exactly what to do, and what order to follow with your improvements. For financial and logistical reasons, you wouldn’t want to perform all recommended upgrades at once. An experienced energy auditor can help you optimize your investment in energy savings by making improvements in the right order.

A present that keeps on giving

There’s everything to gain and nothing to lose by having an energy audit performed on your house. This audit isn’t going to downgrade your credit rating or force you to pay a late fee. There is a penalty, however. Allowing your house to operate as it always has means that its inefficiencies will continue. Your utility costs will continue be high, while your comfort level remains low. Your home deserves the gift of an energy audit, and so do you. The benefits of this gift increase with every improvement you make.

Historic preservation vs. energy-saving renovations 

by Tim Snyder

I’ve lived most of my life in New England, and like many Yankees, I’m proud of our historic buildings. There’s a very special feeling when you drive through the center of a town and see houses that were built two centuries ago, still standing tall and proud today. It’s good to know that we have state and local organizations devoted to the preservation of these venerable structures. This public support is backed up by local historic district regulations and a strong national organization –The National Trust for Historic Preservation.

Despite such widespread support, or perhaps because of it, many people disagree about the type and scope of work that can be done to make an historic house more livable according to present-day standards. There are some obvious “no-no’s,” of course –like covering original wood clapboards with vinyl siding or installing wall-to-wall carpet over a 200-year-old pine board floor.

But once we dispense with these blatant violations of historic character, the water gets murky. Modern plumbing and electrical wiring are essential upgrades. But careful planning and good craftsmanship are required to unobtrusively integrate these amenities into the historic fabric of an antique house. Hopefully, the same careful considerations will go into selecting the cabinetry and appliances to create a modern kitchen in space that’s two centuries old.

Insulation meets historic preservation
Of all the alterations that can and should be done to ensure the survival and preserve the character of historic buildings, energy-saving upgrades should be given a high priority. I’ve recently come across negative comments with regard to filling empty wall cavities in an historic house with injection foam insulation, and it’s this kind of criticism that prompted the blog you’re reading.

Anyone who owns an antique house will tell you it’s a labor of love. But for all the pride these folks take in their historic home, they aren’t museum curators. They don’t sleep on straw mattresses or heat their bath water on a woodstove. They shouldn’t have to shiver through the winter or pay thousands of dollars in extra heating expenses just to preserve a home’s historic integrity. Making the home more energy efficient with modern insulation materials also makes it more affordable to own. Or perhaps more accurately: Spending less on heating and cooling the structure means there’s more money for making historically appropriate repairs to masonry, siding and roofing.

If it’s important to leave finished wall surfaces intact while upgrading insulation levels, injection foam and dense-pack cellulose insulation are your best options. Both materials are injected into wall cavities through holes that are later plugged and finished. Injection foam would be my first choice in an older house because of its superior ability to flow around obstructions, fill voids and seal the huge number of air leaks typically present. Instead of trapping moisture like 2-part spray polyurethane foam would (a characteristic that can damage adjacent wood), injection foam has an open-cell structure that can absorb and release moisture, enabling the wall to “breathe” while significantly improving the home’s comfort and energy performance. It’s also important to note that injection foam doesn’t outgas harmful chemicals as it cures. You won’t see technicians wearing hazmat suits when installing this insulation.

Other modern air-sealing and insulation strategies are equally useful elsewhere in an historic house. Rigid foam won’t sustain water damage or mold growth; it’s also got high R-value and air-sealing ability. Fiberglass batt insulation certainly has a longer history, but rigid foam has some admirable characteristics for old houses, and like any insulation, it can be kept out of sight.

I’m going to let Carl Elefante do the closing for this piece. The principle architect and director of Sustainable Design at Quinn / Evans Architects, Elefante coined the phrase “The greenest house is the one that’s already built.” His essay in the summer 2007 issue of the Forum Journal of the National Trust for Historic Preservation contains the following words:

“To fully capture the value of the existing building stock requires merging two disciplines: historic preservation and green building. It requires an understanding of how to respect and renew what is already here and a vision for where and how to transform the legacy of the past into the promise of tomorrow.”

by Tim Snyder

“I’m tired of paying high utility bills every month. I know my house could be more energy efficient, but I’m confused about what to do first. Will a solar energy system solve my problems? Do I need a new furnace? Maybe new windows are the answer. I can’t afford do it all; that’s for sure, and I don’t know where to begin.”

Making a house more energy efficient is a common objective and a good one, too. Who can dispute the value of spending less on utilities so you can spend more on other stuff? But it’s not easy to figure out what to do first. Contractors who sell replacement windows want to convince you that this is the first energy-saving upgrade to make. The HVAC contractor is certain that a new air conditioning system will net some major savings. Or maybe the plumber has it right, blaming high utility bills on an outdated water heater.

The reality is that improving home energy performance is complicated. A house is a complex collection of different components and systems that interact in different ways. But don’t get discouraged about all the factors, decisions and dollars involved in energy-efficient upgrades.
Believe it or not, there is a logical sequence to follow if you want to improve home energy performance. It’s worth paying attention to these priorities, because making upgrades in the wrong order often causes problems. It can waste money and diminish the savings you’re trying to achieve. For best results, you’ll want to follow the 5 steps explained below.

Step 1: Learn how your house uses & loses energy.

You’ll find plenty of useful information about energy efficiency right here at Dr. Energy Saver. And you can find out even more by contacting the Dr. Energy Saver franchise in your area. One of the things you’ll learn is that every house (and every homeowner) deserves an energy audit — a complete, top-to-bottom look at the systems, features and conditions in and around your house that affect energy performance.

A home energy audit performed by Dr. Energy Saver technicians is more thorough than the audits performed by other companies or agencies. You’ll not only get a detailed “report card” that grades your home in 10 distinct areas of energy performance; you’ll also get a prioritized list of recommendations to improve energy performance.

Step 2: Make building envelope improvements first.

“Building envelope” is a term used by building scientists to describe the shell of a building that surrounds the “conditioned” living space. The condition of the building envelope — how airtight and how well-insulated it is — has a huge impact on home energy performance. Most houses have too many air leaks and too little insulation. As a result, air that you’ve paid to heat or cool can leak out, while unconditioned air leaks in from the exterior. Air-sealing and additional insulation are building envelope improvements that will minimize energy losses and improve interior comfort.

Step 3: Repair & adjust existing systems.

This step can include a wide range of improvements. If your house has a ductwork system, it’s important to seal leaky ducts so that your forced-air heating and cooling systems can work more efficiently. Adding duct insulation is a smart improvement if you have ductwork that is located outside the building envelope (above the attic insulation or in an unconditioned crawl space, for example).

Step 4: Upgrade older systems & products.

An older furnace or boiler may only be able to operate at 65% efficiency even when it’s properly maintained. Replacing this unit with a new 90% efficient model is a smart upgrade. Water heaters, washing machines and dishwashers are other appliances to consider replacing if they’re consuming too much energy. One of the most affordable upgrades you can make is to replace an old-style thermostat with a programmable model that saves energy by automatically letting your HVAC system “rest” at night or when the house is empty. Your energy audit (Step 1) should identify the major “energy hogs” that you can target for replacement.

Step 5: Harness renewable energy.

By the time you get to this step, you’ll already be saving serious money; your house will also be much “greener” than when you started. Steps 1-4 are about conservation; Step 5 moves into renewable energy generation. By installing a solar photovoltaic (PV) system or a solar thermal system, you’ll actually put the sun to work at your house, using clean solar energy in place of energy that consumes fossil fuels. Not all houses are properly situated to take advantage of solar energy. If you have suitable solar exposure and if you’re planning to stay in your house for more than 5 years, this investment is worth considering.

Dr. Energy Saver of Connecticut helps make a beautiful, historic 250-year-old house more energy efficient, by beefing up attic insulation and injecting foam in the existing wall cavities.