Passive Solar Design

Solar Energy For Homes

Passive Solar Design
    - Passive Solar Design
    - Passive Solar Home Designs
    - Sun Spaces

A "passive" solar house provides cooling and heating to keep the home comfortable without the use of mechanical equipment. This style of construction results in homes that respond to the environment.

For passive heating and cooling, the plan of the house, careful site selection and planning, construction materials, building features and other aspects of the home are designed to collect, store and distribute the sun's heat in winter; and to block the sun's rays in summer. Passive solar houses can be built in any architectural style and in any part of the country.

The following techniques use passive solar strategies to provide heat:

Direct Gain is radiant heat resulting from sunlight admitted directly to the living spaces through south-facing windows, which warms the interior surfaces (walls, furniture, floors, etc.). For direct gain, the south-facing window area must be sized for the climate, the type of window used and the amount of thermal mass in the home.

Graphics courtesy of North Carolina Solar Center.

Indirect Gain In a design that employs indirect gain, an attached sunspace or Trombe wall collects heat from the sun before transferring it to other spaces within the home. The air heated in a sunspace circulates naturally or with the aid of fans to other rooms.

Thermal Mass is any material in the home that absorbs and stores heat. Concrete, brick, tile and other masonry materials are the most common choices for thermal mass in a passive solar home, these materials absorb and release heat slowly and are easily and inexpensively integrated into the house design. They are most effective when dark colored and located in direct sunlight. The addition of thermal mass allows saved solar energy to heat the house at night or on cloudy days. The combination increases the performance and energy-saving characteristics of the home, generally for only a modest cost increase.

The following techniques use passive solar strategies to provide cooling:

Passive solar cooling can reduce or even eliminate the need for air conditioning in homes. At its simplest, passive cooling includes overhangs for south-facing windows, few windows on the west, shade trees, thermal mass and cross ventilation. Some of the same strategies that help to heat a home in the winter also cool it in the summer. For example, with a well-designed overhang, the south-facing windows that admit the low-angled rays of the winter sun are shaded from the high-angled summer sun. Thermal mass, which stores heat in the winter to release in the evening, works in reverse in the summer. The mass cools down in the evening and retains that coolness the next day, moderating the effects of high daytime temperatures.

Passive solar design works by utilizing overhangs to shade a house during the heat of the summer and allow sunlight to penetrate the interior of the house during the winter.

Graphic courtesy of North Carolina Solar Center.

Passive solar design utilizes energy efficiency

Energy efficiency minimizes the need for heating, cooling and electricity, solar or otherwise. Designers of solar homes use insulation levels that are higher than those found in typical construction and energy efficiency appliances and lighting.

Windows are up to twice as resistant to heat loss as those used in conventional construction. Air infiltration is also reduced by carefully sealing and caulking around window and door openings and under sill plates.

Adapted from "Consumer Guide to Solar Energy," K. Sheinkopf and S. Sklar, Bonus Books, Inc. and "Buildings for a Sustainable America Case Studies," Burke Miller Thayer, American Solar Energy Society.

Sources of Passive Solar Home Plans

Affordable Passive Solar Homes
ases@ases.org
2400 Central Avenue, G-1
Boulder, CO 80301
(303) 443-3130

This book by Richard Crowther, is available for $21, including postage and
handling, and includes 49 low-cost designs for passive solar homes.

Operation Solar
Northeast Utilities
P.O. Box 270
Hartford, CT 06141-0270
(860) 665-5000

This book includes designs for nine solar and energy-efficient traditional houses
ranging in size from 1,100 to 2,200 square feet. Available at no charge.

Home Designs for Energy Efficient Living
HomeStyles Publishing and Marketing
275 Market Street, Suite 521
Minneapolis, MN 55405
(612) 338-8155

This book, containing about 200 energy-efficient designs, may be ordered by
sending $8.70 (book+postage+handling) to the above address.

Partnership for Advancing Technology in Housing
http://www.pathnet.org/

Planbook for Low-Cost Energy Efficient Homes
Southface Energy Institute
P.O. Box 5506
Atlanta, GA 30307
(404) 515-7657

This planbook includes five solar and energy-efficient low-cost designs, each about
1,000 square feet in size. This planbook has been used by affiliates of Habitat for
Humanity in the construction of several of their homes. One copy may be obtained
by sending $5 to the above address.

Residential Solar Architecture: A Representational Inventory
Nebraska Library Commission
Interlibrary Loan
1200 N Street, Suite 120
Lincoln, NE 68508
(402) 471-2045

A collection of 51 plans, the designs range from 1,500 to 4,000 square feet. This
book is no longer in print, but a copy may be obtained on loan.

Energy-Efficient Home Plans for Kentucky, and
Kentucky Solar Design Awards
Division of Energy
663 Teton Trail
Frankfort, KY 40601
(502) 564-7192

Energy Efficient Home Plans contains 10 plans varying in size from 1,000 to 2,500
square feet. Kentucky Solar Design Awards publishes award winning designs of
various solar projects, including 6 single-family homes.

Sun-Inspired Home Plans
Energetic Design
18250 Tanner Road
Citronelle, AL 36522
(334) 866-2574

suninspired@earthlink.net Debra Rucker Coleman, Architect

http://energeticdesign.homestead.com/

This book includes four sets of designs, each with numerous options for changing size, facade, number of rooms, etc. It also contains an excellent section on energy considerations for those building their own home. Copies of new home plans that have been designed since the original printing are included too. To order this planbook, send $16 to the above address. This price includes shipping.

Solar Homes for North Carolina
North Carolina Solar Center
Box 7401
North Carolina State University
Raleigh, NC 27695-7401
(919) 515-3480
in NC, (800) 33-NC SUN

Published by the Energy Division of the N.C. Department of Commerce, this group
of twelve designs ranges from 1,200 to 2,400 square feet. The plans were
designed to fit well with North Carolina's climate and have been constructed
throughout the state. The planbook is available free from the Solar Center for residents of North Carolina and there is now a second book available. blueprints may be ordered for $7-9. For more information or to order call the NC Solar Center or visit their website at http://www.ncsc.ncsu.edu

Solar Homes for South Carolina
S.C. Energy Office
1201 Main Street, Suite 820
Columbia, SC 29201-3227
(803) 737-8030

This booklet includes eight sketches (1/2 page max.) ranging in size from 1,100 to 2,000 square feet. Please note that these are not full size blueprints.
Available at no charge.

Sunterra Homes
www.homesbysunterra.com

On this website, persons interested in passive-solar home design can view many of our plans and can obtain free information on building science and conservation covering energy efficient design, solariums and alternative energy, air-tight construction with controlled ventilation, radiant floor heating, and low-maintenance products.

The New Florida Home,
The Florida Cracker-Style, and
The Expandable Affordable Home
Public Information Office
Florida Solar Energy Center
1679 Clearlake Road
Cocoa, FL 32922
(407) 638-1000

Each of the above books, available at no charge, contains three or four plans
ranging in size from 900 to 2,100 square feet.

Material taken from North Carolina Solar Center, the Energy Division, N.C. Department of Commerce, and N.C. State University.

Sun Spaces

Homeowners with a sunspace frequently cite it as their favorite room of the house. Sunspaces provide light, warmth, aesthetics, and a healthy environment for plants and people. Sunspaces can also save money on home heating costs. In fact, well-designed sunspaces can provide up to 60% of a home’s winter heating requirements.

Elements of Sunspaces

Sunspaces contain the following elements:

Glass panels, or "glazing," permit light to enter a room, but prevent infrared heat from escaping. This process warms the interior space.
Thermal mass, such as masonry or water, absorbs heat and releases it into the room during extended cloudy weather or at night.
Insulation in ceilings, walls and windows retard heat loss at night and during cold weather.
Climate control features such as operable windows, vents, and fans keep the sunspace from overheating and move warm air to other parts of the house.

Design Considerations

When designing a sunspace, there are several important factors that must be taken into consideration. Your planned primary use of the sunspace will influence some planning decisions:

A sunspace must face south. Due south is ideal, but 30 degrees east or west of south is acceptable. If the south side of the house faces the street, the sunspace must be integrated into the house to avoid a "tacked-on" look.
The sunspace must receive direct sunlight between the hours of 10:00 a.m. and 3:00 p.m. Any object over 10 feet tall within 15 feet of the south glazing is likely to block solar gain.
If the primary function of the room is to provide heat, you can maximize heat gain by using sloped glazing, few plants, little thermal mass, and insulated, unglazed end walls. However, compared to vertical glazing, sloped glazing loses more heat at night, can be covered with snow in the winter, and can cause overheating in warmer weather. Vertical glazing can maximize heat gain in winter, and yields less heat gain in the summer. A well-designed overhang may be needed to shade the glazing in the summer.
If the space is to be used as a greenhouse, remember that plants require lots of light, fresh air, water, and protection from extreme temperatures. Plants consume energy that would otherwise be available as heat. Plants require overhead glazing, which complicates construction, and glazed end walls, which are net heat losers.
As most homeowners wish to use their sunspaces year-round as living areas, the rooms should be designed to have minimum glare and moderate humidity. Carefully sized thermal mass materials will improve comfort levels by stabilizing temperature extremes.

Adapted from: "Sunspace Basics," by the US Department of Energy’s Energy Efficiency and Renewable Energy Network (EREN). There is other good information on sunspaces on the EREN website. In addition, see the North Carolina Solar Center (http://www.ncsc.ncsu.edu/fact/21sunspc.html) for a comprehensive overview of sunspace design.

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