Sustainable Building Technical Manual - Etn-presco.net

Active Solar Systems★ S I G N I F I CA N C E .Active solar collector systems take advantage of the sun to provide energy for domesticwater heating, pool heating, ventilation air preheat, and space heating. Active solar systemsshould be integrated with a building’s design and systems only after passive solarand energy-conserving strategies are considered.Water heating for domestic use is generally the most economical application of activesolar systems. The demand for hot water is fairly constant throughout the year, so thesolar system provides energy savings year-round. Successful use of solar water heating systemsrequires careful selection of components and proper sizing. Major components of asystem include collectors, the circulation system that moves the fluid between the collectorsand storage, the storage tank, a control system, and a backup heating system.4An active solar water heating system can be designed with components sized largeenough to provide heating for pools or to provide a combined function of both domesticwater and space heating. Space heating requires a heat-storage system and additionalhardware to connect with a space heat distribution system. An active solar space heatingsystem makes economic sense if it can offset considerable amounts of heating energyfrom conventional systems over the life of the building or the life of the system. The systemequipment, which can be costly, should be evaluated on a life-cycle basis, usingestablished project financial criteria acceptable to the building owner.. ☛ SUGGESTED PRACTICES AND CHECKLISTIGeneral Considerations❑ Determine if the climate and building usage is appropriate for an active solar collectionsystem.The energy savings for active solar systems depend upon the amount of available solarradiation, projected uses of the system, and the proper system design.❑ Determine the financial feasibility of an active solar system.A life-cycle cost analysis should be carried out for the up-front and operational costs, andexpected energy savings, of an active solar system compared with conventional systems.The financial analysis should be performed over the projected life of the system—a minimumof 10 years. Based on the resulting estimated calculations, the project owner canmake a determination of the financial feasibility of investment in the active solar system.❑ Determine an appropriate location for solar collectors on or near the building.– Locate collectors to maximize exposure to sun. Numerous solar engineering textsdescribe criteria for optimizing the orientation (ideally due south) and tilt of the collectoraccording to latitude, climate, and usage. Collectors intended for winter spaceheating have a steeper slope than collectors designed for year-round hot-water heating.Vertically mounted wall collectors and horizontal roof collectors have also beenused in various systems.– Locate collectors to avoid shading from nearby buildings and vegetation. A study ofsun angles and local sky obstructions should help determine the best location on thesite. For large commercial buildings, the most common location for good solar accessis on the highest level of a flat roof.– Locate collectors to avoid vandalism and safety hazards. Collectors can be attractivetargets for vandals. Their flat surface is well suited to graffiti, and glass cover platescan be broken. The more visible the collectors, the more they may attract the attentionof vandals.