Notes on Passive Solar: Chapter 6

• Structures designed with local climate.
• Natural lighting to decrease electric loads.
• Attributes
  • Simplicity in design
    • No plumbing or control systems.
  • Increased livability
    • Brighter
    • Warm floors and walls
    • Quieter
  • Good performance record.
  • Longevity
    • Nothing to breakdown.
  • Economics
    • Costs are increased some but not appreciably to add passive solar on new construction.
• Design Factors
  • Large area facing south
  • Well insulated
  • Thermal mass for heat storage.
    • Limits temperature swings
  • Open space on the inside.
  • Glassed in porches or sun rooms.
  • Roof overhangs
    • Lets winter sun in
    • Blocks summer sun
  • Double glazed windows, heavy drapes.
    • Limit heat loss at night
  • Adjusted window angles.
    • In Oregon, more orientation towards southwest due to morning fog
  • Reflectors
    • Not a great idea because of glare.
    • Can provide some extra solar gain.
• Direct Gain: Living space is directly heated by the sun. Outside Picture
  • Thick walls and floor to gather heat.
  • Walls and Floors made from materials that have Large specific heat.
  • Roof overhand provides full shade in the summer when sun elevation is 78 degrees above the horizontal.
  • Deciduous trees provide shade on the windows during the summer.
  • Window glazing, 1 sq ft - 4 sq ft floor space.
  • Storage: 150lb of masonry for each square foot of window.
  • Example in Book: Secondary school in Wallasey England
  • Sante Fe Solar House
    • Front solar
    • Back earth berms
    • Insulate windows at night
    • Back up: head wood stove and fireplace
• Passive Solar Pictures
• Indirect Gain: Heat stored somewhere else and transferred to the living space.
• Thermal Storage Walls
  • Massive wall to absorb heat Trombe Wall. The interior of a Trombe Wall in a house
  • Utilizes natural convection, conduction, radiation.
  • Not Utilized often Spoils Southern View.

Outside Temp = Daily Average Temp

Heating Load = BTU / DD - degrees F

Compare Cleveland Ohio to Seattle Washington in January: Heating a Building that requires 20,000BTU/ DD-⁰F

Cleveland (1159DD-⁰F )* (20,000 BTU / DD-⁰F ) = 23.2x10⁶BTU

Seattle (738DD-⁰F) * (20,000 BTU / DD-⁰F ) = 14.8x10⁶BTU

Other stuff:

• Super insulated house: Modern building codes have increased insulation in construction.
• Better windows: Low emissivity (low e) windows, double glazed, filled with argon gas.

• Buildings consume 36% of national energy supply.
• Solar energy and energy efficient technologies could cut 30-80% of energy operating costs.
• Before 1973 - few solar homes in the US (a dozen!), but number increased appreciably in the late 1970's.

Building Integration

• Look at whole building
• Automated energy systems
• Update system
• 30-40% savings in energy costs, which can pay for initial costs

Passive Solar Basics

• Sun facing side of the building for heating
• Light wells, sky lights, or atrium, for natural lighting.
• Roof line designed for solar collectors.

• Suntempered Building
  • Increase the number of windows on the sunny side
  • No extra thermal mass - can save 25% of energy use
• Solar Architecture
  • Increase glazing
  • Add thermal mass
  • Strategies to circulate heat
  • Backup systems
• Cooling
  • Shading
  • Overhangs
  • Ventilation
  • Night flushing
    • Hot dry climates (even Oregon!) nights are 60-70 degrees. Less than 70% humidity. Ventilate building at night to cool off thermal mass and buildings furnishings.
• Improved Window Technology
  • 1976: Inner glass has a low e. metallic oxide. Lower radiation losses. 1995: 1/3 of all window sales. Eugene building codes require low e.
  • Filling with argon adds insulation equal to a layer of glass.
  • Windows can be customized to different climates.
• Design Software
  • Builder Guide Software to design solar houses.
• Daylighting
  • Save on electrical usage
  • Brighten up areas: health and psychological and aesthetic benefits
  • Skylights - 10% of roof area
  • Solar pipe or solar light
  • High tech - taking mirrors and optic fibers
  • Daylighting Energy Saving Potential
  • Daylighting Lillis Hall
  • Solar Megaphone?
  • Other Pictures Lighting and Daylighting
• Other Pictures Passive Solar

Active Solar Space Heating Systems

• For space heating this is currently not used much. Excessive Cost and maintenance.
• Heat water just as making Domestic Hot Water but circulate the water to radiators in the house (Figure 6.29)
• Heat Air with a Flate Plate Collector and circulate through the house. Cold climates with a lot of sun.
  • Fans cost electricity to operate
  • Air not as good a heat transfer mechanism. Low specific heat
• Example on page 188 shows why this is not utilized very often.