Warming With Windows--Passive Solar Primer
How solar energy is used in houses
|Type||Collector Efficiency||Collector Cost||Maintenance||Primary Purpose/ Applications||Energy Storage||Storage cost|
|Photocells (usually on rooftop)||low (less than 20% of incident solar energy)||high||medium to high||Generates DC electrical power which must be converted to AC power for most home applications.||Requires batteries. In some cases the excess energy can be fed back into the power grid.||high for batteries. medium for feed back to grid|
|Active Thermal Collectors (usually on rooftop)||high (depends on many conditions but can exceed 50%)||moderate to high||medium to high||Water and space heating. Uses pumps or blowers to circulate water or air from the storage system to the collector and back.||Water tanks or other thermal masses such as gravel filled containers or phase change materials.||medium|
|Thermo Siphon Thermal Collectors (usually on rooftop)||high (depends on many conditions but can exceed 50%)||moderate||low||Water heating. The tank is placed above the collector in an attic or on a roof. No pump is required.||Water tank||low to medium|
|Passive Solar Design (whole house is the collector)||high (depends on many conditions but can exceed 50%)||low||low||Space Heating||Heavy building materials such as concrete slabs, brick or stone walls.||low to medium|
Passive Solar: In a passive solar house, the house itself acts as the collector and storage system for solar energy. Properly designed, passive solar features will warm a home in the winter and lower air-conditioning bills in the summer without significantly adding to the home's original cost or ongoing maintenance.
5 Key Features of Passive Solar:
- In walls not roofs--roof windows or skylights are hard to shade in the summer and tend to lose heat rapidly in the winter.
- Only south facing windows are effective--By minimizing windows on the other walls it's possible to have more windows on the south wall without a significant increase in a home's cost. East and west facing windows provide little warmth in winter but significantly heat up a house in summer.
- The Sun must shine on the thermal mass.
- The thermal mass should have a dark color.
- The thermal mass has to be in contact with the room's air.
- At night time the thermal mass warms the room's air.
- Aside from heating the air, thermal mass with a lot of surface area located in a room will increase the feeling of warmth due to radiant heat transfer.
- Windows are the major source of heat loss in winter. Movable insulation on large windows greatly reduces this problem.
- Wall, ceiling, and floor temperature is as important as air temperature for comfort level. A degree change in the temperature of these surfaces has about the same impact on comfort as a degree change in air temperature. insulation keeps these surfaces warmer.
- Plantings to act as wind breaks on the East, West, and north sides of the house. These can be deciduous or evergreen.
- Deciduous trees and vines to shade the South side.
Assessment --Investigation of a solar home design
Specifications: Use Google Sketchup to design a 3D solar home with the following features:
Drawing 1:Shows how the house will look. Surfaces must be textured and windows transparent. Furniture and landscaping is not required. Thermal mass must be apparent and positioned so that the sun shines on it. The orientation of longest wall and majority of windows should be to the South. Overhangs must be included and properly designed to block the sun in the summer and let it through in the winter. This drawing includes:
Drawing 2:has no furniture or textures but shows the dimensions on the walls, roof, and floor plan required to build the house
Deliverable:Two 3D Sketchup file stored in your student drive labeled Passive Solar House 1 <your name> and Passive Solar House Dimensions <your name>.
Work Group: individuals.