Passive Solar Buildings.pptx

Contents • • • • • • • • • • • • • • •

What are passive solar buildings? Constructional Elements for residential buildings How does passive solar design use the sun’s power? How does it work? Systems involved Radiant panels Thermal storage walls Trombe walls Concrete walls Concrete block walls Water walls Material considerations Benefits Levels of application Conclusion

Introduction •

Industrial and technological innovations, population growth, and rapid urbanization lead to an increase in energy consumption. • Dependency on foreign sources of energy and their negative environmental impact have made energy efficiency and conservation critical issues. • 35–40% of our energy is consumed by buildings, and 85% of that is need solely for heating.

What are passive solar buildings? • “In PASSIVE SOLAR BUILDINGS, windows, walls, and floors are made to collect, store, and distribute ’SOLAR ENERGY’ in the form of heat in the winter and reject solar heat in the summer.

Elements considered for residential buildings construction • Placement of room-types, internal doors & walls, & equipment in the house. • Orienting the building to face the equator. • Extending the building dimension along the east/west axis • Adequately sizing windows to face the midday sun in the winter, and be shaded in the summer. • Minimising windows on other sides, especially western windows. • Using thermal mass to store excess solar energy during the winter day (which is then re-radiated during the night).

How does passive solar design use the sun’s power? • Procedures for design of buildings to passively use solar energy for heating buildings may typically involve: • Use of shading devices to reduce heating by radiant (solar) energy in the summer and allow it in winter, • Utilize thermal convection (i.e. hot air rises) to maximize heating by convection in winter, and • Utilize thermal storage (mass-effect) to transfer excess heating capacity from daylight to night time hours.

How does it work? • Passive solar buildings are designed to let the heat into the building during the winter months, and block out the sun during hot summer days. This can be achieved by passive solar design elements such as shading, implementing large south-facing windows, and building materials that absorb and slowly release the sun’s heat.

Systems Direct Gain Indirect Gain Day lighting

Direct Gain

Indirect gain

Day lighting

Radiant panels Radiant panels are simple passive solar systems that are inexpensive and well suited as retrofits to metal buildings.

Thermal storage walls • A thermal storage wall is a passive solar heating system in which the primary thermal storage medium is placed directly behind the glazing of the solar aperture. • Heat transfer to the living space is sometimes augmented by the addition of circulation vents placed at the top and bottom of the mass wall.

Trombe Walls In summer The density of the materials in the Trombe wall acts as a method of slow heat absorption and transfer.

Continued… In winter • In the winter, when the sun is allowed to shine on them, they can be ‘charged’ up to help to warm the house by transferring the sun’s heat inside. • In the winter, when the surrounding outside air temperature drops as the air cools after the sun has gone down, the object with thermal mass will continue to release its stored heat energy. • When all the heat is discharged, it is ready to once again ‘charge’ up or absorb heat again.

Concrete Block Wall: • Concrete block buildings are very common they may offer opportunities for passive solar retrofits. • Concrete floor slabs and massive partitions between zones help prevent overheating and otherwise improve the performance of concrete block thermal storage walls • For new construction, superior performance of solid masonry walls by filling the cores of the block in the thermal storage wall with mortar as it is erected.

Water walls •

Water walls are thermal storage walls that use containers of water placed directly behind the aperture glazing as the thermal storage medium. • It is more advantageous than a trombe wall by using half the space and being effective at much higher heat capacities. • The advantage over masonry walls is that water has a volumetric heat capacity about twice that of high density concrete; it is therefore possible to achieve the same heat capacity

Material Consideration •

When designing energy-efficient buildings, it’s necessary to know the solar heat gain of materials used on the structure’s exterior Glass and plastic blocks Patterned glazing Skylights Sunshades Roof structures Tubular daylighting devices Solar screens Electrochromic and photochromic glazings Translucent or solar-absorbent product.

Skylights Skylights are a simple way of introducing light to rooms right below roof level. Both fixed and operable skylights are available. Angled (splayed) walls broadcast the most light, and placing skylights near a wall creates a pleasant light-washing effect on the wall surface. . Skylights also can produce unexpected glare and uncomfortably warm indoor temperatures unless they have shades. With this in mind, in most climates it is wise to limit skylights to north roof slopes

Windows and glazing • In terms of energy efficiency, glazing is a very important element of the building envelope. • Glazing transfers both radiant and conducted heat • Daytime heat gain must be balanced against night time heat loss when selecting glazing areas. • Window frames can conduct heat. Use timber or thermally separated metal window frames in cooler climates.

Working method of following: 1. 2. 3. 4. 5.

Trombe wall Water wall Solar chimney Earth bunding Earth ship

Passive solar buildings for study: 1. Druk white lotus school 2. Environmental sanitation institute