Remodeling an existing home can be the most environmentally sound way to improve one's living situation. The amount of materials and energy saved in reusing existing portions of a home can be very significant. Concrete, wood, plaster, wiring, plumbing, stone, tile, and many more components all contain embodied energy from the initial manufacturing, transportation and construction processes. The re-use of these components essentially can become a gigantic recycling enterprise. This enterprise can be very rewarding financially as well as beneficial to the planet.
When considering a remodel for a reduction in energy use, there is a whole cornucopia of options: from the simple and relatively inexpensive, such as appliance replacement, to the more expensive and complex, such as adding photovoltaic panels and active solar collection. But let's start with the easiest to implement.
If your home is more than 20 years old, chances are you have a furnace (hot air system), boiler (hydronic system) and/or water heater that are inefficient and outdated. New furnaces available today range in energy efficiency from 85% to 92%. Some boilers manufactured today are in the 90% to 98% efficiency range. Old models of furnaces and boilers built between 1930 and 1970 ranged from as low as 40% up to only 75% efficient. As you can see, when adding today's energy rates into the mix, replacement of an old, inefficient unit can result in a tremendous savings in winter energy bills. When it comes time to replace a leaking or worn-out water heater, a tankless unit will pay for itself in reduction of energy costs in a very short period of time. Keeping that old tank full of hot water 24/7, regardless of use, is a real waste of fuel. There are now solar water heaters that have a payback period of less than 6 years available to most homeowners. This seems like a pretty darn good return on investment.
The use of fluorescent lighting can reduce energy consumption for lighting by as much as 80% and can last up to 10 times as long as conventional bulbs. There are a number of products on the market today that make fluorescent use more appealing. These improvements include full-spectrum tubes and daylight tubes, which produce a quality of light previously unavailable in fluorescent bulbs. One downside of this lighting is the fact that there are trace amounts of mercury in all fluorescent bulbs and tubes. Recent changes in urban recycling efforts have made that much less of a concern. We now have the opportunity to recycle these items in a regular hazardous waste pickup provided by the city. New products utilizing LED's (light emitting diodes) are just now emerging on the market. Similar to fluorescents, these products save considerable energy and the diodes themselves, last virtually forever.
Many homes in the Santa Fe area were historically built with little or inadequate insulation. A typical home here today may have an insulation value-or R-value-of 0 to 10 in the walls and 5 to 24 in the roof. R-value is the ability of a material to resist the movement of both hot and cold air. Ideally, the insulation value in an energy efficient home will range from 18 to 40 in the walls and 30 to 60 in the roof. Extra insulation and insulation performance can be achieved by adding rigid or spray-on insulation to both the walls and the roof without tearing up the walls or ceilings.
The envelope of the house refers to the exterior shell and all of its openings or penetrations. These include windows, doors, skylights, utility entry and exit points, etc. The efficiency of that exterior shell is critically dependent on the individual components and their efficiency. A home with well-built insulated windows and doors can offer up to 40% energy savings over a leaky, drafty set of old windows and doors. Here is an area where a well-thought-out remodel and well-researched components, properly installed, can substantially reduce the energy footprint of your home.
There is a story in New Mexico that an adobe structure is warm in the winter and cool in the summer. That myth comes from the old days when all adobe homes would have multiple fireplaces and/or woodstoves burning 24/7 all winter long. The tremendous mass of the adobe walls and dirt roofs were heated and kept heated, not allowing the "thermal flywheel"-or thermal storage-to slow down. The net effect of this was structures that were cozy to live in. Unfortunately, this denuded the surrounding hills of many northern New Mexico towns like Santa Fe, of almost all trees. The air quality in the winter, especially during an air inversion, was abysmal. A much more effective use of thermal mass, whether it be adobe or concrete walls, brick or tile on concrete slabs, is to insulate the outside of exterior walls and under the floors. That way the mass has the opportunity to hold the heat and slow down the thermal release, thus maintaining the thermal flywheel with much less added energy. The reason a passive solar adobe works so well is because the sunlight penetrates the south-facing glazing-or windows-during the day, heats up the mass of the interior adobe walls, thrombe walls and/or masonry floors and contributes to the momentum in the thermal flywheel.
Active solar gain refers to heat gain that depends on assistance from pumps or fans to move the heated medium, such as water and other liquids in a hydronic system and air in a forced-air system. These systems can be the most costly portion of a remodel for energy efficiency. The good news, however, is that with new, more efficient collectors being introduced every year, and federal and state rebates currently available, the payback period for these systems make them a very good investment. As the cost of energy increases in the next few years, the installation of active solar becomes more and more attractive. Considering the current stock market fluctuations, investing in the reduction of our home heating bills seems brilliant.
The technology of silicon wafers for the production of electricity has taken a huge step forward in the last few years. In just the last few months, Ava Solar announced the construction of a new factory that will hire five hundred people and be producing photovoltaic panels for one dollar per watt! This is a huge breakthrough considering the average PV panel right now costs four to five dollars per watt. Thanks to an agreement between the State of New Mexico and PNM, there are not only state rebates available for installing new PV systems, but PNM will buy the electricity back from the home owner/producer for more than you currently pay per kilowatt-hour. Once again, the pay-back period for this sustainable technology is being reduced every year.
Estimates show that the average kitchen accounts for 20% to 40% of a home's total energy bill. If your refrigerator and dishwasher are more than ten years old, you can probably reduce your electric bill substantially by replacing these appliances with high-efficiency models. There is of course, an initial investment with upgrading old appliances, but you'll experience superior, normally quieter performance and lower utility bills. An added bonus for us here in New Mexico is that PNM has just implemented a refrigerator rebate program that picks up your old working but inefficient unit, recycles it, and sends you a check. To find the most energy-efficient electric appliances, you can go to the Energy Star website, or look for the Energy Star label at your retailer. An Energy Star label means that a product meets stringent energy requirements. For tips on cooking appliance selection, see the Rocky Mountain Institute Home Energy Brief.
The well-designed outdoor space speaks to the home and can contribute to the comfort, aesthetics AND energy reduction of the structure. Well-placed trees, shrubs and arbors can be planted to increase shading of windows and thereby reduce summer passive gain. Deciduous trees and shrubs can be used in these areas so their wintertime shading is radically reduced after the leaves have fallen, allowing increased solar gain.
Architecture 2030: www.architecture2030.org
U.S. Department of Energy: www.energy.gov
Rocky Mountain Institute: www.rmi.org
Energy Star: www.energystar.gov
Ava Solar Company: www.avasolar.com
Passive house: www.passivehouse.us
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