PASSIVE SOLAR DESIGN ALTERNATIVE ENEGRY SOURCES Solar Design

PASSIVE SOLAR DESIGN ALTERNATIVE ENEGRY SOURCES

Solar Design The Sun and Solar Radiation provide energy for… § Heating and cooling a building § Water heating § Daylighting § Electrical generation via Photovoltaic cells We will focus on how we can use the sun to aid in the heating of water.

Solar Design Here a few reasons why solar hot water systems make good environmental sense: • On-site energy generation: Reduce the need to extract and transport fossil fuels. • Increased boiler and water heater efficiency and life expectancy • Reduced greenhouse gas emissions: • A 50 -collector solar hot water system can offset over 50 tons of CO 2 per year, or 5, 000 tons over the life of the system. • A 100 -collector pool-heating system can offset over 80 tons of CO 2 per year

Solar Design Passive solar design § Solar energy is collected, stored, and distributed without the use of mechanical equipment

Solar Design § Sun charts can be used to determine the best design for rook overhangs and other shading devices

Solar Design Direct Gain Systems § Collect heat through South-facing glass and store the heat in high-mass materials such as concrete floors or masonry walls. § During nighttime hours the high-mass material slowly release the heat gained during the day Indirect gain Systems § Similar to direct gain systems except that thermal mass is not in direct sunlight. § Heated during the day by room air temperature and reflected sunlight. § Less efficient then direct gain systems Trombe Wall § Vents at top and bottom to allow thermocirculation

Solar Water Heater

Passive Solar Water Heating Systems Passive solar water heaters rely on gravity and the tendency for water to naturally circulate as it is heated. There are two basic types of passive systems: q Integral collector-storage passive systems q Thermosyphon systems

Passive Solar Water Heating Systems Integral collector-storage passive systems q Consist of one or more storage tanks placed in an insulated box with a glazed side facing the sun. q These work best in areas where temperatures rarely fall below freezing. q They also work well in households with significant daytime and evening hot-water needs. q They do not work well in homes or buildings with predominantly morning draws because they lose most of the collected energy overnight.

Passive Solar Water Heating Systems Thermosyphon systems q Rely on the natural convection of warm water rising to circulate water through the collectors and to the tank (located above the collector). q As water in the solar collector heats, it becomes lighter and rises naturally into the tank above. Meanwhile, the cooler water flows down the pipes to the bottom of the collector, enhancing the circulation. q Indirect thermosyphons (that use a glycol fluid in the collector loop) can be installed in freeze-prone climates if the piping in the unconditioned space is adequately protected.

Passive Solar Water Heating Systems Backup Systems Solar water heating systems almost always require a backup system for cloudy days and times of increased demand which a conventional water heater serves as.