Healing Appalachia: Sustainable Living through Appropriate Technology

5. Solar Heating Applications

When we redesigned and remodeled to incorporate into our new passive solar addition overall improvements in insulation, airtightness, daylighting, appliance and lighting efficiency, we also added as many efficiency upgrades to the older parts of our home as possible, including a new more efficient heat pump. My office, like my household, prefers and uses as much used, refurbished, and high-recycled-content products and materials as possible. Many of our waste materials are recycled or composted. And yes, we do hang-dry our laundry when outdoor conditions permit, since each avoided use of the electric dryer saves 4–5 kWh, associated with over 10 pounds of carbon dioxide emissions when kilowatt hours come from burning coal. John F. Robbins, certified energy manager, Morningview, Kentucky Sunshine is in plentiful supply in Appalachia much of the year. As of now, solar energy is free for all to use. It warms the Earth and delights our souls, allows plants to grow, and gives us light by day. In solar heating applications, the basic methodology is to capture the sun’s rays, convert them to heat, and retain that heat as long as possible through heat-storage systems and specific conservation measures. Solar energy offers several general advantages: Once the application is built, there are no additional fuel bills, for solar energy is free. CHAPTER 5 Solar Heating Applications The energy is renewable and comes at no cost to the environment , whereas nonrenewable fossil fuels result in air and water pollution. There are no worrisome long-lived toxic waste products as in nuclear power generation. The process offers opportunities for decentralized energy sources and is not dependent on sometimes fallible centralized utility systems. Solar applications make users continually aware of the need for conservation and prudent use of natural resources. Additional advantages are listed in the appropriate sections. SOLAR WATER HEATING A majority of the world’s population does not bathe with domestic heated water but washes with cold or tepid water. Domestic hot water, regarded as a necessity in the developed world, is considered a luxury by many. Water heating accounts for an estimated one-tenth of domestic energy consumption (some estimate upward to one-quarter) depending on use patterns. The developed world uses enormous amounts of heated water, often wasting it by needlessly running faucets and showers before and after use. While avoiding pollution and at the same time building economic infrastructure, much domestic water heating could be achieved by solar heating devices. Certainly, solar hot water systems are a proven long-term application. Photographs of the April 18, 1906, San Francisco earthquake show damaged buildings with solar hot water systems on their roofs. Solar heating of water began long ago when people set containers of water in the sun to warm. Many of the world’s people could obtain their domestic hot water through Solar Heating Applications ❖ 71 easy-to-build simple devices. In all respects, solar hot water is the premier solar application, the one that experts regard as having the fastest payback and using the least amount of natural resources. The basic question for a household is how much hot water is needed. In households where not everyone showers at the same time of day, a domestic water system could have far less storage capacity, and cost less, than if much hot water is demanded within a short period. Electric or gas-fired units that heat on demand can be integrated into the domestic water system; these units save energy when compared to gas or electric water heater storage tanks. However, because they use nonrenewable energy, they are not nearly as friendly or efficient as solar water heating systems with storage tanks of any size. Solar water heaters must be located on or near the portion of the building that faces south or slightly southwest or southeast, and the site should be accessible for initial construction and for later maintenance. The design should be visually pleasing and in harmony with the building’s architecture, and the heater should be constructed to withstand typical wind speeds. To avoid leaks, care must be taken in combining metal and plastic materials for piping. Since water-storage systems are heavy (a 100-gallon system could weigh half a ton), placing large systems on roofs or in lofts could require substantial reinforcement of roofing or flooring systems. For retrofit situations , the system can typically be positioned on the ground next...