Home Science: August 2010

Thursday, August 26, 2010

200,000 Homes and Counting...

By Douglas DeMers - Working with the Weatherization Assistance Program here in Philadelphia has given me an enlightened, community-level perspective on the initiatives of state and federal groups striving to help make America's homes more energy efficient for its low income residents.

Weatherization and energy efficiency is essentially the foundation of all green building retrofit work; it comes before implementation of more advanced alternative energy concepts and sets the path to a truly greener world.

But even at this base level, training people to be good weatherization energy auditors can be a slow process. Converting the old workforce to a new way of thinking is necessary and inevitable, but it isn't going to happen overnight. Likewise, there are plenty of challenges when offering to do such work in places that might not be as tranquil as imagined.

One valuable lesson I've learned in the WAP program is that good communication, customer service, and community outreach skills are a necessity. As an energy auditor trained to work in some of the more poverty stricken areas of urban Philadelphia, cultural sensitivity is key, as well as learning how to cope with adverse situations. The job is part tradesman, part educator, and perhaps, part social worker.

The mission of the program, which has been in place in Pennsylvania since the 1970's, is not simply to seal homes and tune-up appliances, but to advocate good habits of energy efficiency to folks who could benefit from them most, and thus save money for themselves, the government, and help the planet too.

Perhaps the advice might be simple things like not blocking heating air vents or radiators with furniture, or making the living zone more comfortable and cooler in summer by shutting window blinds or draperies on the southern exposure of a home during a sunny afternoon. Maybe it's a quick talk about how air circulates through a building, and which way to run window and ceiling fans to adjust the indoor temperature and comfort level. Whatever the case, if the message is communicated in a friendly manner and with sensitivity, people will greatly appreciate your recommendations.


	Oil burning residential heater.

But the real job satisfaction of being a WAP auditor goes beyond gratitude given for finding ways to save people money on their ever-soaring energy bills. The golden reward is the notion that you can turn folks around, that you can inspire people to become enthused with home science and energy efficiency, and essentially, contribute to making a better world.

The positive impact of that on the big picture is tremendous. It helps the economy, people's social well-being, and the environment. I've seen clients from low income housing communities become so interested in the work done on their homes that they, themselves, have joined WAP training programs and gone on to become expert weatherization workers. Thus the feedback loop revolves, and brings with it hope and knowledge to communities struggling to rise from the grips of adversity. These are the inspirational and often untold stories about plight of urban life that need to be told - not the usual bleak, cliche, dark sides, that our newspapers seem all too eager to sensationalize and exploit.


	Diagram showing methods of heat transfer.

So while you can see that many of us are enthusiastic and working hard to make this little known sector of the green jobs economy a great success, one might ask, exactly how are we doing?

Well recently Vice President Biden announced some pretty ecouraging statistics regarding the nation's weatherization goals and accomplishments in a press release from the Department of Energy's Energy Efficiency and Renewable Energy website:

At an event with homeowners and workers who benefited from the program, today in Manchester, New Hampshire, Vice President Joe Biden announced a major Recovery Act milestone—the weatherizing of 200,000 homes under the Recovery Act. As a result of the Administration's unprecedented commitment to energy efficiency, more than 200,000 low-income families have been able to save money on their energy bills while saving energy, and thousands of people have been put to work.

Vice President Joe Biden

"Thanks to the Recovery Act, thousands of construction workers across the country are now on the job making energy-saving home improvements that will save working families hundreds of dollars a year on their utility bills," said Vice President Biden. "From replacing windows and doors to adding insulation, these are small changes that are making a big difference for American workers, manufacturer and consumers. We've hit the accelerator on the weatherization program, making over 200,000 homes more energy-efficient already, and are now full speed ahead to meet our original target of weatherizing 600,000 homes nationwide. "

"The weatherization program under the Recovery Act—one of our signature programs—is successfully delivering energy and cost savings for hundreds of thousands of American families while creating thousands of clean energy jobs in local communities," said U.S. Energy Secretary Steven Chu.

Auditor flue gas analyzer.

Vice President Biden today visited the Manchester, New Hampshire home of the Dumont family to announce the milestone. The Dumont family is expected to save over $600 a year on their utility bills once their weatherization project is completed and Southern New Hampshire Services, the local organization weatherizing their home, has already hired 7 new full-time employees and an estimated 68 subcontractors as a result of the Recovery Act weatherization funding.

New Hampshire has been one of the nation's weatherization leaders, ramping up quickly and effectively to reach their goals ahead of schedule. Through June, New Hampshire has weatherized a total of more than 1,000 homes under the Recovery Act. New Hampshire was also recently selected to receive an additional $3.1 million to complement and expand their existing weatherization program, drive innovation, and deliver even greater energy bill savings for local families.

New Hampshire's efforts are contributing to the success of the program nationwide. After ramping up last year, the Weatherization Assistance Program is now weatherizing homes at its optimal rate—approximately 25,000 homes per month. With 200,000 homes weatherized nationally, states are more than a third of the way to reaching the President's goal of weatherizing nearly 600,000 homes under the Recovery Act. This summer alone, more than 80,000 homes are being weatherized nationwide versus 3,000 last summer. Including homes weatherized with annual program funding, more than 300,000 homes have now been weatherized since the Recovery Act began.

US residential electricity consumption through 2008.

The weatherization program is also creating thousands of jobs locally—putting carpenters, electricians, and factory workers back to work installing insulation, upgrading appliances, and improving heating and cooling systems. According to state reports, the Recovery Act Weatherization Assistance Program supported more than 13,000 jobs in the second quarter of 2010, including approximately 120 jobs in New Hampshire. These workers are receiving training in energy upgrades that will help form the foundation for a sustainable energy efficiency industry in America that can extend to the more than 100 million middle-class homes that stand to benefit from weatherization.


	Philadelphia green jobs training center.

The U.S. Department of Energy's Weatherization Assistance Program helps lower-income families save energy and money by improving the energy efficiency of their homes. According to a recent study by Oak Ridge National Laboratory, weatherization services save families an average of more than $400 in energy costs during the first year after home retrofits are installed. Overall, the Administration is investing about $90 billion through the Recovery Act in clean energy and energy-efficiency projects that cut costs, reduce energy use and create new jobs.

Now that's some good news for a change. America, let's keep up the nice work!--D.A. DeMers.

Wednesday, August 4, 2010

Sealing the Envelope

Home Energy magazine. Source: Flicker

Sealing the envelope of the home is at the core of weatherization and home energy science. Before moving on to more advanced measures in green-building, air sealing and insulating the thermal boundary of a home must first be achieved. The US Department of Energy, through its Energy Efficiency and Renewable Energy office, recently published some very useful information regarding these essential weatherization tactics on their Energy Saver's blog (shown below).

Weatherization and energy efficiency in homes and other buildings has become a significant area of study and concern as energy rates continue to soar, and the depletion of natural resources and degradation of the environment remains considerably problematic. Weatherization programs are in place throughout many states, in both private and public sectors, and retrofit installers, crew chiefs, and energy auditors are rapidly becoming fast-track career fields in the home-building trades.--D.A DeMers

Your Home

Air leakage, or infiltration, occurs when outside air enters a house uncontrollably through cracks and openings. Properly air sealing such cracks and openings in your home can significantly reduce heating and cooling costs, improve building durability, and create a healthier indoor environment.

It is unwise to rely on air leakage for ventilation because it can't be controlled. During cold or windy weather, too much air may enter the house. When it's warmer and less windy, not enough air may enter. Air infiltration also can contribute to problems with moisture control. Moldy and dusty air can enter a leaky house through such areas as attics or foundations. This air in the house could cause health problems.

The recommended strategy in both new and old homes is to reduce air leakage as much as possible and to provide controlled ventilation as needed.

For more information from the Department of Energy, see the following resources:

Note that air sealing alone can't replace the need for proper insulation throughout your home, which is needed to reduce heat flow.

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In addition to the DOE's air sealing article above, here are some insights I've included on insulation issues for specific climates, as well as other weatherization related situations:

Climate Map of the US. Source: Google Maps

Cold Climates

In cold conditions, the main aim is to reduce heat flow out of the building. The components of the building envelope - windows, doors, roofs, walls, and air infiltration barriers are all important sources of heat loss; in an otherwise well insulated home, windows will then become an important source of heat transfer. Heat loss can be reduced by good weatherization, bulk insulation, and minimizing the amount of the building's non-insulative glazing. Some insulated glazing systems can greatly increase R-values, the industry's measure of thermal resistance.

Hot Climates

In hot conditions, the greatest source of heat energy is solar radiation. This can enter buildings directly through windows or it can heat the building shell to a higher temperature than the ambient air, increasing the heat transfer through the building envelope. The process is called solar heat gain, a measure of heat transmittance via sunlight in a home.

Central Air Conditioners. Source: GNU

Solar gain can be reduced by adequate shading from the sun, light colored roofing, heat-reflective paints and coatings and various types of insulation. Specially coated glazing can reduce SHG to around 10%. Thermal insulation is material specifically designed to reduce the flow of heat by limiting conduction, convection, or both.

Radiant barriers are materials which reflect radiation and therefore reduce the flow of heat from radiation sources. Good insulators are not necessarily good radiant barriers, and vice versa. Metal, for instance, is an excellent reflector and poor insulator. Radiant barriers are highly effective for attic spaces in hot climates. In this application, they are much more effective in hot climates than cold climates. For downward heat flow, convection is weak and radiation dominates heat transfer across an air space. Likewise, radiant barriers must face an adequate air-gap to be effective for the rest of the envelope.

If air-conditioning is utilized in a home in a hot, humid climate, then it is particularly important to seal the building envelope. Dehumidification of humid air infiltration can waste significant energy. On the other hand, some building designs are based on effective cross-ventilation instead of air-conditioning to provide convective cooling from prevailing breezes.

Building Envelope

The thermal envelope defines the conditioned or living space in a house. The attic, basement, or any porches may or may not be included in this area. Reducing airflow from inside to outside, or "tightening the envelope," can help to reduce convective heat transfer significantly.

The less natural airflow into a building, the more mechanical ventilation will be required to support human comfort. High humidity can be a significant issue associated with lack of airflow, causing condensation, rotting construction materials, and encouraging microbial growth such as mold and bacteria. Moisture can also drastically reduce the effectiveness of insulation by creating a thermal bypass.

Thermal Bypass

Thermal bypasses or "bridges" are points in the building envelope that allow heat conduction to occur. Since heat flows through the path of least resistance, thermal bridges can cause reduced energy efficiency. A thermal bypass is created when materials create a continuous path across a temperature difference, in which the heat flow is not interrupted by thermal insulation. Common building materials that are poor insulators include glass and metal.

A building design may have limited capacity for insulation in some areas of the structure. A common construction design is based on stud walls, in which thermal bypasses are common in wood or steel studs and joists, which are typically fastened with metal. Notable areas that most commonly lack sufficient insulation are the corners of buildings, kneewall in attic spaces, chimney chase-ways and voided areas where insulation has been removed or displaced to make room for system infrastructure, such as electrical boxes, plumbing, fire alarm equipment. Utilizing proper insulating materials for such spots or limiting the cross-sections can minimize the bypass.

Materials

Insulation Matthew Bisanz

There are essentially two types of building insulation - Bulk Insulation and Reflective Insulation. Most buildings use a combination of both types to make up a total building insulation system. The type of insulation used is matched to create maximum resistance to each of the three forms of building heat transfer - Conduction, Convection, and Radiation.

Bulk insulators block conductive heat transfer and convective flow either into or out of a building. The denser a material is, the better it will conduct heat. Because air has such low density, air is a very poor conductor and therefore makes a good insulator.

Insulation materials to resist conductive heat transfer, or radiant barriers (see above), use air spaces between fibers, inside foam or plastic bubbles and in building cavities like the attic. This is beneficial in an actively cooled or heated building, but can be a liability in a passively cooled building where proper provisions for cooling by ventilation or radiation are needed.

Some radiant barriers are particular to specific spectral frequencies and will, for example, reduce the flow of infra-red radiation in comparison to other wavelengths.

Likewise, low-emissivity windows will transmit light and short-wave infra-red energy into a building but reflect back the long-wave infra-red radiation generated by interior furnishings. Similarly, special heat-reflective paints are able to reflect more heat than visible light, or vice-versa.

Thermal emissivity values probably best reflect the effectiveness of radiant barriers. Some manufacturers give an equivalent R-value for these products. However, these numbers are sometimes difficult to decipher, since R-value testing measures total heat loss in a lab and does not necessarily include situations involving radiation, conduction, or convection.--D.A DeMers (in collaboration with documented sources).