House as a System
Technology Snapshot & Benefits:
When building new energy-efficient houses or making existing houses more efficient significant energy gains can be realized, just by treating the "House as a System". You cannot make changes to one part of a house without affecting the many other parts that make up the house system. The house system is made up of the building envelope (foundation, walls, ceiling), the heating and cooling system, the water heating system, the lighting system, the appliances, and a fireplace if present.
Estimated Cost Savings:
Making the home as tight as possible has an incredible impact on your heating and cooling bills.
Issues:
Tight homes need sealed-combustion furnaces and water heaters or outside air for combustion in wood-burning fireplaces. Common mistakes include putting non-sealed combustion furnaces and water heaters or wood-burning fireplaces in tight energy-efficient homes. With a tight house, something as simple as turning on your dryer or a down-vented range can pull the ashes and combustion by-products right out of the fireplace or down the chimney of the furnace or water heater and back into the house.
Increasing the insulation in a wall or attic without sealing the air leaks from the inside into that space can lead to mold and rotting problems.
Proper roof insulation is important to prevent ice damming on roofs.
Regional Issues:
In cold climates, sealing penetrations on the inside into walls and attics is important in keeping the moist inside air from getting into the cold spaces and condensing. In warm climates, it works the other way around. You need to keep warm moist outside air from reaching the back of the drywall that can be colder due to air conditioning.
Sealed combustion appliances are a must for any climate region.
Installation (Getting It Done):
With a new house, you want to build it as tight as possible. Install sealed combustion gas appliances and a controlled ventilation system.
More Information On This Topic
Building Science Corporation: House Design Recommendations by Climate Region
Building Science Corporation's guidelines for quality energy-efficient design and construction.
The Energy and Environmental Building Association Criteria
The Energy and Environmental Building Association (EEBA) has developed goals, objectives and criteria for energy and resource efficient buildings. They provide guidance for design, construction and comprehensive rehabilitation (gut-rehab) of low-rise residential and small commercial buildings less than 20,000 square feet (1,900 m2) floor area.
Low-Flow Toilets
Technology Snapshot & Benefits:
Low-flow toilets are specifically designed to use less water during each flush. This is an important feature in an increasing number of areas throughout the country where water is limited. In all parts of the country, low-flow toilets make simple sense by conserving a natural resource used for routine and mundane tasks. To gain an appreciation of what a low-flow toilet can mean to you and your community, take a field trip to your local sewage treatment plant and look at the effort and expenditure required to treat sewage and reclaim water. Low-flow toilets make sense, particularly in water-constrained areas.
Estimated Cost Savings:
Water is still an under-valued resource but general understanding of its importance is growing. Mark Twain may have had it right when he commented "We know the worth of water when the well runs dry." A state-of-the-art low-flow toilet may consume less than two gallons of water per flush compared to five or more gallons with "old" technology toilets. The new toilets can cut your expenditure for flushing in half, or more. Yet flushing is only part of your annual water budget and you should pay some attention to the performance of your clothes washer and dishwasher as well.
Issues:
For new homes, getting a low-flow toilet may not be an option – it may be required by local building codes. Like most consumer items, retrofit models can vary in their design and effectiveness. For a good coverage of issues, see Consumer Reports, October, 2002, page 52.
Regional Issues:
Toilet options may depend on local building codes and sources of supply.
Installation (Getting It Done):
Be sure to get bids from two or three (or more) plumbers to gain immediate perspective on the true value and costs of low-flow toilets in your area.
More Articles on This Topic:
U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy: Toilets and Urinals
U.S. Department of Energy's Federal Energy Management Program: Energy Cost Calculator for Urinals and Toilets
Sealing the Existing Home
Technology Snapshot & Benefits:
Most people aren't aware that air leakage amounts to 30-40% of a home's heating and cooling bills. Stopping air leakage is important not only for energy savings, but also for protecting your home from the damaging effects of moisture. Air, leaking into walls from the interior of the home, carries humidity with it. This moisture hits a cold surface and condenses, causing the insulation and surrounding wood to get wet. Eventually, the air leakage can lead to mold growth and wood rot.
It is a common misconception that the majority of a home's air leakage comes through windows and doors, but in actuality, only 10-15% of air leakage is through windows and doors. That is why window replacement is seldom a cost-effective means to save energy. There are lots of ways to greatly improve the efficiency of windows without replacing them.
The use of a blower door can make locating and sealing air leaks much easier. A blower door is simply a large door with a fan in it that allows you to pressurize a home so you can use smoke sticks to find air leaks.
Estimated Cost Savings:
Properly sealing your home can save you 30-40% of your heating and cooling costs.
Issues:
Sealing up the outside of your home without sealing up the inside, traps moisture in your walls and can lead to mold growth and wood rot. Sealing up your home without providing outside air for combustion in gas furnaces, water heaters, and wood burning fireplaces can lead to air quality problems and could even allow carbon monoxide to build up in the home.
Regional Issues:
Reducing air leakage is something that needs to be done for homes in all regions of the country.
Installation (Getting It Done):
Most people think that tightening up the home means caulking around the outside of the home. This prevents rain water from getting into your walls and that's important, but does very little to stop air from leaking into your home. Tightening up an existing home begins on the inside. The greatest areas of air leakage in a home are around the top of the foundation and around penetrations into the attic. You can seal the top of the foundation (rim joist) with caulk or expanding foam. To seal the penetrations into the attic, the easiest way is to push back the insulation, and seal the holes around wiring and plumbing stacks and caulk along to tops of interior walls. To seal the inside of the house, use a clear caulk around the window frames where the trim meets the wall and all cracks in the window that aren't operable. Add weatherstripping to the windows if necessary. Install foam gaskets on outlets and switches on exterior walls. Use clear caulk along the basement where it meets the floor. Seal around all ceiling fixtures, heat registers, medicine cabinets, bath tubs, kitchen cabinets, drain and water pipes where they enter the wall in kitchen and bath and any other interior wall penetrations. There are many things you can do to reduce air leakage in your home. However, keep in mind that professional with the proper training and equipment is best suited to pinpoint air leakage and to identify and deal with combustion safety problems.
More Information On This Topic:
Iowa Energy Center: Energy Saving Ideas
Complete checklist of what you can do to save energy in your home and the order that you should do it in.
Air Seal and Insulate with ENERGY STAR
Iowa Energy Center: Home Tightening, Insulation, and Ventilation
Geothermal Heating Systems
Technology Snapshot & Benefits:
Geothermal heating systems, also known as geo-exchange, ground source pumps, or earth-coupled pumps, take advantage of the earth's nearly constant temperature (45-75 degrees Fahrenheit, depending on latitude) to heat and cool buildings. They work by pumping water and antifreeze or a refrigerant under the ground to be heated or cooled by the earth and then pumped back through piping in the house. In the winter, the earth is used as a heat source, and in the summer as a heat sink. These systems are effective in any climate. The systems pollute less than traditional fuel-burning systems and are about three times more efficient. They are also more efficient than air-to-air exchange heating/cooling systems because water can transfer a greater amount of heat than air. They also have a longer lifetime than either system because almost all system components are indoors or underground. The average lifetime is 25 years for outdoor components and 50 years for parts that are installed indoors or underground.
Geothermal systems reduce the probability of a fire or carbon monoxide leak in a home because they do not require any combustion. Another huge benefit is the reduction of pollution. According to the Geothermal Heat Pump Consortium, geothermal systems reduce CO2 emissions by about 1.1 million metric tons over 20 years, which is "the equivalent of converting about 58,700 cars to zero-emission vehicles, or planting more than 120,000 acres of trees." Geothermal systems have the EPA ENERGY STAR® label, which not only indicates that using these systems benefits the health of our planet, but also that there may be incentives associated with installing the system, such as tax benefits or lower mortgages. Geothermal systems are also better at controlling relative humidity in buildings compared with other systems.
There are two different types of geothermal heating and cooling systems: open-loop and closed-loop. Open-loops systems require a body of water, and work by pumping water from this source through the house and then back into the body of water. In closed-loop systems, closed-loop piping through which water flows is buried under the ground. The piping for closed-loop systems may be installed vertically or horizontally, with vertical piping requiring a deep but thin trench and horizontal piping requiring a wide but shallow trench.
Geothermal systems are very popular among people who have used them. In fact, the California Energy Commission's Consumer Energy Center reports that 95 percent of people who have installed these systems would recommend them to others.
Estimated Cost Savings:
Geothermal heating systems can save between 30 and 70 percent on heating and cooling costs compared to traditional fuel-burning systems, and are estimated to use an average of 25 to 50 percent less electricity. These systems are often able to generate excess heat in the summer or even the winter, and a device called a desuperheater can use this excess heat from the system's compressor to heat water at no additional cost. These systems are expensive to install, costing about $2,500 per metric ton of unit, which works out to about $7,500 for the average-sized American home. This is nearly double the price of installing a traditional air conditioning unit. Closed-loop systems require an additional cost for drilling the trench in which the piping is laid, which can cost $10,000 to $30,000, although the costs of installation have decreased in recent years and are expected to continue falling. Overall, the long-term monetary benefits of transitioning to a geothermal system outweigh the initial cost. The U.S. Department of Energy estimates that the installation costs will pay for themselves in five to ten years, and then building owners will actually profit from the system for the remainder of the system's life. Schools and businesses, which will probably be using the system for a long time, could take special advantage of this profit to purchase new school or business necessities.
Besides saving money on monthly energy bills, geothermal heating systems are usually more durable and require fewer maintenance and repair costs compared with other units. Having a geothermal system adds value to a property proportional to how much monthly energy bills are reduced. Some states also offer monetary incentives for installing these systems.
Property owners who want some of the benefits of a geothermal system but simply cannot afford installation can consider an air-geothermal hybrid system, called a dual-source system. These systems are less efficient than a pure geothermal heating and cooling system, but more efficient than a pure air-based or fuel-based system. Also, dual-source systems are cheaper to install than pure geothermal ones.
Issues:
It is very important to get a qualified contractor to look at the building and land around the building to determine the best kind of geothermal system to maximize comfort, efficiency, and savings. All systems should be customized to a particular situation. It is very important to make sure the contractor is knowledgeable and qualified.
Open-loop systems are initially cheaper to install because they do not usually require drilling; however, it is important to note that these systems work only where there is a sufficient amount of fresh, relatively clean water available. If this is the case and an open-loop system may be used, you must research local regulations on discharging water and make sure these regulations are met.
Regional Issues:
Geothermal heating systems work in all climates, even extreme ones. Good contractors should be able to give advice on specific regional issues that affect drilling and installation, for example, very hard ground.
Installation:
Installation and installation costs of geothermal systems vary, depending on the type of system installed and the availability of a water source. All installations, however, involve installing some type of piping and units for converting and distributing heat. The ductwork used in these systems is the same as that used for traditional systems, so no change is required during installation. The most important thing about installation is finding a good contractor.
More Information On This Topic:
"Geothermal Heating/Cooling Systems" - Residential Environmental Design
"Geothermal Heat Pumps" - U.S. Department of Energy, Energy Efficiency and Renewable Energy
Geothermal Heat Pump Consortium
"Geothermal or Ground Source Heat Pumps" - California Energy Commission, Consumer Energy Center
Heating - Central Location for Heating Unit
Technology Snapshot & Benefits:
Combustion units for heating buildings may often be advantageously located centrally within the floor plan of the building. Such placement offers extra radiant heat recovery from a furnace or boiler proper and most importantly from the entire length of the chimney as it progresses upward throughout the house. A centrally located chimney typically provides better "draw," since the chimney walls are not chilled by outside temperatures. This design is easy to accomplish in new construction, and a bit more challenging, but still possible, in existing structures.
Estimated Cost Savings:
Cold chimney walls inhibit the upward flow of exhaust gases. In practice, this retarding effect is often overcome by furnace adjustments that send more heat up the flue with an attendant loss in fuel, economic and environmental efficiency. Locating a furnace or boiler centrally in the building may yield savings on the order of 5-10%. For a monthly heating bill of $200 dollars, this equates to an estimated savings of $10-20 per month. For a new building, centrally locating the heating unit may incur no (or very low) additional costs, yet the savings will be permanent. For an existing structure, moving a heating unit to a central location is most cost-effective when the old unit reaches the end of its useful life and it is time for replacement. If these alterations cost $1,000, an improvement of this nature pays for itself over 9-10 years. At the same time, monthly cash-flow improves immediately.
Issues:
Existing building architecture may inhibit centrally located combustion unit. Wood-fired units may present a housekeeping challenge due to small bits of bark, leaves and other debris often associated with the movement of wood fuels. Costs to modify an existing structure may be prohibitive unless coupled with other planned renovations.
Regional Issues:
The value of this modification depends upon the annual heating requirement of your furnace or boiler. The National Climatic Data Center provides an historical record of departures of average daily temperatures from a reference temperature of 65 degrees F. This information is available as "Heating Degree-Days per Year" and provides a very useful estimate of how often your heating plant will run.
Installation (Getting It Done):
Masonry chimneys on outside walls are prohibitively costly to move unless coupled with a planned renovation. An additional triple-walled chimney may be used to advantage after checking with local fire codes.
Heating - High Combustion Efficiency (equal to or greater than 90%)
Technology Snapshot & Benefits:
There are easy savings to derive with improved combustion efficiency. Many buildings are heated by burning fuels imperfectly in furnaces or boilers. Owners and occupants benefit from high efficiency equipment and modern designs that efficiently convert energy contained in the fuel into useful heat for building occupants. The more efficient this conversion, the less fuel is required for a given level of comfort with corresponding cost and pollution savings.
Estimated Cost Savings:
Frequently, tests of existing heating units reveal operation at 50-60% combustion efficiency. High-efficiency replacement units (with combustion efficiencies of 90% or greater) reduce fuel costs (and corresponding pollution) by 30-50% over existing units, depending upon site-specific particulars. It is not unreasonable to achieve improvements of 30 cents on the dollar in heating costs for residential and commercial buildings. For a monthly heating bill of $200 dollars, this equates to an estimated savings of $60 per month. If the upgrade to higher efficiency costs $2,000, a improvement of this nature pays for itself in substantially less than five years, and improves cash-flow immediately.
Issues:
Some units extract so much heat from the flue gas that water vapor (a normal product of combustion) condenses in the chimney before it can be vented to the outside. Special drainage means may be required with high efficiency units, but this is frequently an inconsequential consideration.
Regional Issues:
Depending on your heating degree days per year, combustion efficiency improvements are as big a winner as you can find.
Installation (Getting It Done):
We encourage you to get two or three bids from HVAC and/or plumbing contractors as you move to take advantage of this savings opportunity. Obtaining a range of bids will provide you with immediate perspective on the true costs of equipment and installation in your area.
More Information On This Topic:
U.S. Department of Energy - How to Buy an Energy-Efficient Residential Gas Furnace
U.S. Department of Energy - How to Buy an Energy-Efficient Commercial Boiler
Energy Star - Guide to Energy-Efficient Cooling and Heating
Heating - Outside Source for Combustion Air
Technology Snapshot & Benefits:
Combustion units for heating buildings benefit from drawing combustion air directly from the outside using sealed and insulated ductwork. The advantages of this are two-fold: 1) conservation of warm indoor room air; and 2) reduced infiltration of cold outside air through cracks in windows, doors, and elsewhere in the building envelope. When combustion air is drawn from a heated basement room, it returns to the outside via a chimney after supporting combustion in the firebox. This loss of air slightly depressurizes the interior of the building, and pressure recovery is most likely through leaks to the outside. Bringing combustion air to the firebox through an insulated and sealed duct solves this problem.
Estimated Cost Savings:
A typical home furnace, rated at 80,000 Btu/hour, may operate at a duty cycle of 50% (it is operating about half of the time). To support this combustion, X cubic feet of air per hour are required, or 24X cubic feet of air per day, more or less, depending upon how much your furnace runs. Savings accrue from retaining warm indoor room air and particularly from reduced infiltration of cold outside air. Drafts, particularly annoying to occupants, are eliminated or greatly reduced. In dollars, this translates to a potential savings of 5-10 cents on the dollar for the heating costs of the typical home or building owner. For an average heating bill of $200 per month, this translates into a savings of $10-20 per month, directly to the bottom line.
Issues:
Enabling ductwork may present logistical issues to rooms that are already finished. These are often easily overcome.
Regional Issues:
The value of this modification depends upon the annual heating requirement of your furnace or boiler. The The National Climatic Data Center provides an historical record of departures of average daily temperatures from a reference temperature of 65 degrees F. This information is available as "Heating Degree-Days per Year" and provides a very useful estimate of how often your heating plant will run.
Installation (Getting It Done):
The air intake source should be covered with a screen to prevent access by rodents and pests.
Heating, Ventilation, and Air Conditioning
Technology Snapshot & Benefits:
HVAC (heating, ventilating, and air-conditioning) refers to the equipment, distribution network, and terminals that provide either collectively or individually the heating, ventilating, or air-conditioning processes to a building.
Estimated Cost Savings:
HVAC accounts for 40% to 60% of the energy used in U.S. commercial and residential buildings. This represents an opportunity for energy savings using proven technologies and design concepts.
Issues:
HVAC systems have a significant effect on the health, comfort, and productivity of occupants. Issues like user discomfort, improper ventilation, and poor indoor air quality are linked to HVAC system design and operation and can be improved by better mechanical and ventilation systems. In existing buildings, envelope upgrades are often necessary to maximize comfort and energy efficiency, such as reducing envelope leakage. (Click on the link below to read the complete article.)
Residential Buildings
More Information On This Topic:
Energy Star®: A Guide to Energy Efficient Heating & Cooling
Kansas State University: Selecting a Home Heating System
Energy Efficiency and Renewable Energy Clearinghouse: Cooling Your Home Naturally
Energy Efficiency and Renewable Energy Clearinghouse: Programmable Thermostats
Energy Efficiency and Renewable Energy Clearinghouse: Cooling Your Home with Fans and Ventilation
Energy Efficiency and Renewable Energy Clearinghouse: Energy Efficient Air Conditioning
Radiant Floor Heat
Technology Snapshot & Benefits:
Radiant floor heating can be extremely cost-effective and comfortable. There are three types of radiant floor heat: radiant air floors, electric radiant floors, and hot water radiant floors. Hot water radiant floors, or hydronic systems, are the most cost-effective systems for homes or buildings in heating-dominated climates. Hydronic systems heat water in a boiler and pump the heated water through tubing underneath floors. Most find radiant floor heat to be one of the most comfortable types of heating, because heat is evenly distributed from the floor, warming up the feet and body first. The benefits to radiant floor heating are numerous and include increased levels of comfort due to the silent operation of the system. Radiant floor heat eliminates drafts and dust problems associated with forced air systems. Additionally, radiant floor systems areinvisible. There are no heat registers or radiators.
Estimated Cost Savings:
The estimated cost savings associated with the use of radiant floor heating range from 10-40% on utility bills. Due to the fact that radiant heated floors distribute heat evenly, homeowners can set their thermostat 2-4 degrees less than in a forced air heating system, which leads to reduced energy costs. Contact your local utility company to confirm what a 2-4 degree temperature decrease would equal in savings.
Compared to other hydronic heating systems, radiant floor heating allows for lower boiler temperatures, saving energy and increasing boiler life expectancy. A 45-year life is not unusual.
Issues:
With radiant floor heat, some floor coverings perform better than others. Ceramic flooring is the most common. If you want carpeting, install a thin carpet with dense padding and use as little carpeting as possible. Some floors take longer to heat than others. If a floor is allowed to cool completely, make sure to give adequate time for the floor to heat-up.
When working with a hydronic system, it needs to circulate water continuously using valves and manifolds. These valves and manifolds can be prone to mechanical and maintenance issues as well as sedimentation. If a hydronic installation develops a leak, it can be challenging to repair.
Regional Issues:
Radiant floor systems can also be used to cool spaces. Currently, the available systems are only appropriate for dry climates.
Installation (Getting It Done):
The three types of radiant floor heating breakdown further when installed into "wet" or "dry" installations. During the older form of installation, a "wet" installation, cables or tubing are inserted within a solid floor. The solid floor can be a layer of slab concrete, gypsum, or any other material that is installed on top of a subfloor. When applying a "wet" installation consult a professional to determine the floor's carrying capacity. In a "dry" installation, cables or tubing run in the air space beneath the floor. "Dry" installations are increasing in popularity due to the fact that they are cheaper and faster.
Be sure to get two or three (or more) bids from designers and/or contractors to gain immediate perspective on the actual costs of radiant floor heat equipment installation in your area.
More Articles on This Topic:
U.S. Department of Energy' Office of Energy Efficiency and Renewable Energy: Radiant Heating
U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy: Building Technologies Program - Radiant Floor Heat
Oregon Department of Energy - Radiant Floor Heating
Radiant Panel Association
Water Heating - Instantaneous Water Heaters
Technology Snapshot & Benefits:
Easy economic savings can accrue from instantaneous or the "on-demand" type of water heaters. In contrast to the traditional method of keeping 40 to 80 gallons of hot water at-the-ready in an insulated tank, "on-demand" heaters produce hot water only when it is needed. Since hot water is generally required for less than a few hours each day instead of 24, owners and occupants can easily benefit from high efficiency modern designs that provide hot water on demand. Less fuel is required for a given volume and temperature of water, with corresponding cost savings and pollution savings. Some manufacturers claim 50% savings when compared to conventional hot water tanks.
Estimated Cost Savings:
Assuming that you consume the same amount of hot water at the same temperature as before, you can save a lot of energy and money by eliminating the slow leakage of heat from the hot water tank and piping. Actual savings will depend upon how much water you use, how far it must be piped from your existing heater, and the extent to which that piping travels through unheated spaces. It is reasonable to expect improvements in your hot water bill of 20 cents on the dollar. For a monthly water-heating cost of $50 dollars, you may expect savings of $10 per month on your energy bill. If the switch to "on-demand" water heating is made when your old hot water tank conks out, the effective net cost of change will be much lower and your monthly cash-flow will improve immediately.
Issues:
Installation will be required in the immediate vicinity of bathroom, kitchen and/or laundry room. Space may be a concern.
Regional Issues:
If the new units are electric, you may wish to consider the stability of the electrical grid in your part of the country. Additionally, electricity is most often produced by large central-station plants and is delivered to you at an overall efficiency of about 30%. Unless your electricity is produced with renewable energy equipment, natural gas or LP gas are the fuels of choice for hot-water heating (just as with traditional hot water tanks). These fuels provide total system efficiencies of 80-90%.
Installation (Getting It Done):
If the new water heaters are fueled by natural gas or LP gas, there may be some fuel delivery piping and exhaust venting issues to be addressed by the installer. If the new units are electric, expect some minor rewiring and the installation of new circuit breakers.
Be sure to get bids from at least two or three installers and/or plumbing contractors to gain immediate perspective on the true costs of equipment and installation in your area.
More Information On This Topic:
U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy - Demand (Tankless or Instantaneous) Water Heaters