EXECUTIVE SOLAR ENERGY FOR PACIFIC NORTHWEST RESIDENTIAL HEATING MAY 1978 U.S. D.O.E. U.S. D.O.E. U.S. E.P.fl. SEATTLE RICHLAND SEATTLE ------- SOLAR ENERGY FOR PACIFIC NORTHWEST RESIDENTIAL HEATING EXECUTIVE SUMMARY REPORT An Interagency Report by: The U.S. Department of Energy Region X Office of the Regional Representative The U.S. Department of Energy Richland, Washington Operations Office, and The U.S. Environmental Protection Agency, Region X Office May 1978 ------- This Executive Summary is a condensation of a technical report that examines climatic, technical, economic, legal, institutional, and environmental issues related to development of solar energy for residential space and water heating applications in the Pacific Northwest.* The report provides objective information for those considering installing a solar system. AVAILABLE SOLAR ENERGY IN THE PACIFIC NORTHWEST There is a wide variety of opinion regarding the practicality of solar heating in (for example) Seattle which has a national reputation for dark, rainy winters. Some people believe solar heating is more practical in Spokane or Boise where there is more winter sun. That is not correct. To illustrate this point, a comparison of winter heating requirements and available solar energy for various Northwest and selected other locations is shown in Table I on the next page. 'Throughout this report, "Pacific Northwest" and "Northwest" are used to indicate the geographical area comprising the States of Washington, Oregon, and Idaho. ------- SOLAR RADIATION AND HEATING DEGREE-DAY COMPARISON FOR VARIOUS NORTHWEST AND SELECTED OTHER LOCATIONS Table I (A) (B) (C=A/B) Average Daily Average Monthly Ratio of Solar Energy Solar Radiation Heating Degree— Received to Heating Received During Days During Degree—Days During Location the Heating Season* the Heating Season** the Heating Season*** Richland, WA 720 690 1.04 Seattle, WA 520 660 0.79 Spokane, WA 660 920 0.72 Astoria, OR 560 610 0.92 Corvallis, OR 530 610 0.88 Klamath Falls, OR 810 840 0.96 Medford, OR 750 700 1.07 Boise, ID 810 820 0.99 Twin Falls, ID 840 860 0.98 Great Falls, MT 770 1,000 0.77 Boston, MA 680 800 0.85 Schenectady, NY 640 950 0.67 Chicago, IL 530 880 0.60 Madison, WI 710 1,100 0.64 ~Average daily solar radiation (Btu/ft2 ) rounded to two significant digits, for the months of October through March. ~~Heating degree—days (base 65°F) rounded to two significant digits, for the months of October through March. Heating degree—days are a measure of temperature as it affects energy demand for space heating. For any one day, it is equivalent to the difference between the mean temperature for the day and 65 F. The greater the number of degree—days, the greater the heating demand. ~ ~~This ratio is calculated by dividing the amount of solar radiation received, column (A), by the heating degree days, column (B). For Richland, Washington, for example, C=A/B=ggQ=1.04. The higher the number, the better the location for solar heating. -1- ------- In summary, the following are conclusions of the report concerning available solar energy in the Pacific Northwest: • Based only on climatic factors, the attractiveness of solar space heating is relatively uniform throughout the Northwest. This uniformity is due to two related conditions. West of the Cascade Mountains, it is cloudier, but more temperate; east of the Cascades, there is more available solar radiation, but the winters are colder. These conditions roughly balance each other. The Richland, Washington area and the Medford, Oregon area appear to be the most attractive areas for solar heating applications. • Based on climatic factors, the attractiveness of solar space heating is better for all Northwest locations studied than for a variety of other representative Northern U.S. locations surveyed: Chicago, Illinois; Madison, Wisconsin; Schenectady, New York; and Great Falls, Montana. • Based on a consideration of available solar radiation, solar water heating, which is not usually affected by outside air temperatures, appears to be more attractive in clear-sky eastern portions of the region. • Solar collection in Northwest latitudes is improved significantly during winter months by tilting collector surfaces 45° to 60° above horizontal, facing south. Available solar energy on such inclined south-facing surfaces is approximately twice that of horizontal surfaces during November, December, and January. TECHNOLOGY AND ECONOMIC ANALYSIS The systems studied in this report include active and passive space and water heating applications as well as solar heating for swimming pools. Passive solar space heating systems collect energy through direct heat gain without use of pumps, fans, or other mechanical equipment. In effect, the building itself becomes a live-in solar collector. Considerable research on passive space heating systems suitable for the Northwest has been performed at the University of Oregon. Initial results are impressive, suggesting that a properly designed passive system can perform as well as or better than active* systems, although there is no §imple or set way to calculate "years-to-break-even" because of the wide number of variables in passive solar system design. ~An active solar system is one that uses coliectors, pumps, piping, fans, and other mechanical equipment to move the heat collected. -2- ------- For example, the performance of a well-insulated house with a 12-inch thick concrete thermal storage wall equal in area to 1/2 the house floor area has been computer simulated for different cities in the Northwest. The results are as follows: Percent Space Heating City Supplied by Passive Solar Eugene, OR 59 Medford, OR 71 Seattle, WA 60 Spokane, WA 61 Boise, ID 71 To estimate the "years-to-break-even" for an active solar heating system: 1) Determine the cost of conventional heating energy by calling your utility or 2) Determine the approximate installed cost and collector area of the are considering either from a solar system company estimate or a estimating guide. 3) Divide the estimated solar system cost by the number of square feet of solar collector area. 4) If you use gas or oil, convert to an equivalent electricity price using Table II below. TABLE II Equivalent Energy Costs Oil,* Natural Gas,* Electricity, $/gal $/therm $/kwh 0.28 0.23 0.01 0.43 0.35 0.015 0.57 0.47 0.02 0.71 0.59 0.025 0.85 0.70 0.03 1.00 0.82 0.035 1.14 0.94 0.04 1.28 1.05 0.045 1.42 1.17 0.05 5) Select the appropriate Figure (I, II, III, or IV below) representing the city nearest to your home,** draw a vertical line from your equivalent electricity cost to the estimated solar system cost curve, and from that point draw a horizontal line over to the vertical axis. This is the approximate "years-to-break-even" for an active solar heating system in your area. ~Assumes average furnace efficiency. **For a more accurate result if you are not located near any of these cities, refer to the full technical report which includes charts for 12 different Northwest locations. heating fuel dealer. solar system you reliable published -3- ------- NEW CONSTRUCTION COST OF ELECTRI CITY cents/kWh This example illustrates how to find estimated "years-to-break-even" periods. Assume that you are buying oil at $.57 per gallon, and that you have received a quote for an active solar system of $20 per square foot of collector. The electricity price equivalent (from Table II) is H per kwh. The vertical dotted line is drawn up from the 2^/kwh and the horizontal line shows that it would take slightly less than 13 years to "break even", that is, it would take 13 years for the system to pay for itself. -4- ------- 14 - 12 - 10 - 8 - 6 - 4 - 2 - 0 - 14 - 12 - 10 - 8 - 6 - 4 - 2 - 0 - BOISE, ID HOT WATER SYSTEM NEW CONSTRUCTION ADDED TO EXISTING STRUCTURE COST OF ELECTRICITYcents/kWh COST OF ELECTRICITY cents/kWh HOT WATER AND HEATING SYSTEM ADDED TO EXISTING STRUCTURE NEW CONSTRUCTION COST OF ELECTRICITY cents/kWh COST OF ELECTRICITY cents/KWH FIGURE I Economic Analysis for Boise, ID ------- 14 - 12 - 10 - 8 - 6 - 4 - 2 - 0 - 14 - 12 - 10 - 8 - 6 - 4 - 2 - 0 - CORVALLIS, OR HOT WATER SYSTEM ADDED TO EXISTING STRUCTURE NEW CONSTRUCTION COST OF ELECTRICITYcents/kWh COST OF ELECTRICITY cents/kWh HOT WATER AND HEATING SYSTEM NEW CONSTRUCTION ADDED TO EXISTING STRUCTURE COST OF ELECTRICITY cents/kWh COST OF ELECTRICITY cents/kWh FIGURE II Economic Analysis for Corvallis, OR —6— ------- SEATTLE, WA HOT WATER SYSTEM NEW CONSTRUCTION 1 2 3 4 5 COST OF ELECTRICITY cents/kWh 14 12 10 5 ct m e un CtL s > ADDED TO EXISTING STRUCTURE X _L 1 2 3 4 5 COST OF ELECTRICITY cents/kWh HOT WATER AND HEATING SYSTEM NEW CONSTRUCTION 5 > UJ s az ca 6 ADDED TO - EXISTING STRUCTURE - \$io/ft2c . ¦ -,1 1 i 1 i 1 2 3 4 5 COST OF ELECTRICITY cents/kWh 1 2 3 4 5 COST OF ELECTRICITY cents/kWh FIGURE III Economic Analysis of Seattle, WA 7 ------- 14 _ 12 - 10 - 8 - 6 - 4 - 2 - 0 - 14 - 12 - 10 - 8 - 6 - 4 - 2 - 0 - SPOKANE, WA HOT WATER SYSTEM ADDED TO EXISTING STRUCTURE NEW CONSTRUCTION COST OF ELECTRICITY cents/kWh COST OF ELECTRICITY centslkWh HOT WATER AND HEATING SYSTEM ADDED TO EXISTING STRUCTURE NEW CONSTRUCTION COST OF ELECTRICITY cents/kWh COST OF ELECTRICITY cents/kWh FIGURE IV Economic Analysis of Spokane, WA ------- In summary, the following are major conclusions of the report concerning Northwest solar economics: • Passive solar heating can often be integrated into new buildings as part of the architecture at minimal additional cost. According to a University of Oregon study, some passive systems can meet 60 to 70 percent of a residence's space heating needs in the Northwest. Passive systems can be, dependent upon the design used, the most cost effective application of solar heating. • Currently, the most effective residential application of active solar heating in the Northwest is a swimming pool heater. Typical "years-to-break-even" periods for solar swimming pool heaters are less than ten years. • Currently, active solar space and water heating systems are less cost effective than the other solar applications studied. Typical payback periods for active solar space and water heaters are longer than ten years. • It appears that the solar/heat pump combined cycle studied by the Northwest Energy Policy Project group has typical "years-to-break-even" periods longer than 15 years. LEGAL ASPECTS OF SOLAR ENERGY DEVELOPMENT There are various private and public law doctrines which may affect a solar user's right to sunlight, and which may have an effect on the widespread use of solar energy. Briefly: • In general, present law does not adequately protect access to sunlight for users of solar energy. • Under present law, restrictive covenants can be a primary method for protecting access to sunlight for new real estate developments. However, restrictive covenants do not usually provide adequate protection for solar energy users in areas that are already developed. • The adoption of a "solar skyspace easement" law, under which easements negotiated between private parties could be recorded in a standard format, would appear to offer improved legal protection for many solar energy users in developed areas. • The use of restrictive covenants and solar skyspace easements can offer increased legal protection for many users of solar energy while minimizing the need for modification of the present legal system. — ------- • Any major modifications in the legal system, such as allocation of sunlight under the prior appropriation system currently used for water allocation in the Western States, or under some form of permit procedure, must be carefully considered to determine whether the resulting increase in regulation can effectively solve the problems presented without creating serious negative effects, such as over-restriction of adjacent property. ENVIRONMENTAL CONSIDERATIONS There are minor potential air, water, solid waste, and health impacts of widespread solar development. Both positive effects (reduced air and water emissions from conventional energy sources) and negative effects (disposal of toxic fluids, increased glare, potential contamination of potable water systems) exist. Air pollution was also found to affect the availability of received solar radiation. Thus, air pollution could impair the performance of solar heating systems. The full report describes all the above issues in more detail. The report may be reviewed at the Public Reading Area, U.S. Department of Energy, Room 1902, Federal Building, 915 2nd Avenue, Seattle, Washington. A limited number of copies are available for distribution to interested parties. -10- ------- |