Energy and the Human Environment
Toward Better Neighborhood Design
By Judy and Michael Corbett
Published by: College of Human Ecology, Michigan State University
Energy costs are eating up an ever-increasing percentage of the family income today. Home utility bills are doubling and tripling. The price of gasoline for the family car continues to rise. The family budget is impacted both directly and indirectly. Almost every product we use, from food to soap, requires energy to produce, transport and market. When the cost of energy rises, it creates an increase in the cost of everything else.
Not only are utility rates rising, but crime rates and a sense of alienation also seem to be on the increase. The sense of community, once a valued part of urban and rural life, is rarely found in today's neighborhoods. With neighbors no longer looking out for one another, home burglaries have become commonplace. Teenage drug abuse and pregnancy have increased and other signs of an unhealthy society have emerged.
In 1973, we tackled an ambitious project -- to design and build a better place to live, addressing both of these problems by 1) designing a neighborhood which would reduce the amount of energy required to carry out the family's daily activities, and 2) establishing a sense of neighborhood community.
Construction of our dream, Village Homes, began in 1975 and the community is now almost fully constructed. Village Homes is a seventy-acre subdivision in Davis, California. It is comprised of about two hundred and forty living units, including twenty apartments in a mixture of price ranges from small, 600 square foot commonwall homes, to 2,800 square foot detached family dwellings. There are also twenty apartment rental units. The neighborhood includes greenbelts behind every house, agricultural areas, a recreation center for neighborhood use, swimming pool, bike paths, playgrounds and professional offices. Eventually a small inn, restaurant, co-op store and some light industry will complete the neighborhood.
Reducing Neighborhood Energy Use
How do you design a neighborhood community which will significantly reduce energy consumption? To answer that question, one must know how energy is used by a typical family. Some research uncovered for us the following:
Family energy use in Davis:
Obviously, the major use of energy for a typical Davis family is automobile transportation. To reduce this expensive dependence on the car, both in Village Homes and to a lesser extent the City of Davis, a concerted effort has been made to promote walking and bicycling. Bicycles and pedestrians are encouraged in Village Homes by the separate bike and pedestrian paths (running through greenbelts) and the circulation pattern. We deliberately made it easier and faster to walk from one area to another in the development rather than drive there. And the whole network is tied into the city bikeway network. Numerous recreational facilities as well as the provision of jobs for members of the community in a commercial center and in agricultural projects have also reduced the dependence of residents on the automobile.
Space Heating and Cooling: The Neighborhood Site Plan
The second largest use of energy is for space heating and cooling. The very simple steps necessary for solar utilization were among the first made and most vigorously pursued. They included street orientation, lot orientation, setbacks, solar access, and landscaping.
Street orientation was probably the most important step. Streets run predominantly east-west to ensure that houses have their major walls on the south and minimal exposure on the east and west. By itself, this "sun tempering" can reduce energy use for heating and cooling twenty to fifty percent.
The second modification was of the shape of each lot to make sitelines run north - south even on gently curving streets. This minor and important change was unacceptable to FHA loans and thus conventionally financed all the housing.
The third technique used to minimize energy use for heating and cooling involved changes in streetside setback requirements for front, back and side yards. Houses are set comparatively further back from the street when a courtyard is needed to enclose extensive south glass and give privacy. A fence may be as close to the street as ten feet or as close to a parking bay as two feet. The house may be placed within five feet of the back property line.
The fourth step involved protection of solar access and essentially established solar rights for residents for the development. Through the design review process and the covenants of the development, exposure to the sun is carefully protected. Before construction begins, a model of each house is made and placed on a large plan of the development. An architectural review board makes certain that buildings do not shade one another. Shading due to vegetation is prevented by special amendment to the Homeowner's Covenants, Code and Restrictions.
The next change involved better use of landscaping material. Trees, for example, are carefully chosen for maximum shade in the summer with fast leaf drop in the fall and minimum branching to reduce shading in the winter. Winter exposure is also protected by placing trees predominantly on the east and west of houses where their shade is most helpful for cooling.
Finally, the streets were kept as narrow as possible (twenty to twenty-six feet in width) and guest parking was provided in parking bays. The narrow streets and parking bays can be more thoroughly shaded than a wide street, thereby reducing summer heating demands.
Neighborhoods in Davis with narrow shaded streets have been shown to be a full ten degrees cooler on hot summer days than neighborhoods with wide, unshaded streets.
Space Heating and Cooling: The House
Although the homes in Village Homes use a large variety of solar systems, they all share a few concepts and details of design and construction which make them exceptionally energy-efficient. These general energy conservation features include 1) good insulation, 2) extensive use of south facing glass with overhangs, 3) the incorporation of high mass material and 4) window placement for cross ventilation. Some of these are specifically designed to fit the Davis climate, but most of them are applicable almost anywhere.
The climate in Davis is known as a Mediterranean climate. This describes a fairly temperate climate with strong marine influence. The summer days are hot (reaching 100 degrees regularly), but as the hot air rises over the Sacramento Valley, it draws in the cool air form the Pacific Ocean and nighttime lows are comfortably cool, averaging about 56 degrees over the summer. The Pacific also moderates the winter extremes, and freezing temperatures are a fairly rare occurrence.
Careful insulation is one of the first steps in reducing energy demand in a house. Walls and roofs are almost always insulated now, but thicker insulation is often desirable. Many of the houses in the Village Homes have used two-by-six walls instead of two-by-four walls so that more insulation can be put between inner and outer walls to increase their resistance to heat flow. Roof insulation is typically R30, compared to R19 in standard houses nearby.
Insulating the other exposed areas of a house is also important and often not done. For example, the edge of the floor slab is often not insulated and as a result the slab provides a path for unwanted heat loss in the winter and heat gain in the summer. It is inexpensive and easy to add insulation to the edge of the slab during construction, and all of the builders in Village Homes do so as a standard practice.
Windows are another area where energy conservation must be considered. Although the primary concern is usually radiation gain from sunshine, windows are also an important factor in conductive heat loss in the winter and unwanted heat gain in the summer. A single pane window, for example, has an R value of only 0.9 or only 1/20 that of the typical wall used in Village Homes. The use of thermal pane windows increases the R value to 1.8 which is better, although still not very good. As a result, many of the houses in Village Homes further improve their windows by providing thermal shutters or drapes. These come in many types with widely different costs and vary from R values of only two to three to an impressive nineteen.
Another facet of energy conserving design is the choice of exterior color for the walls and roof, and the choice of roofing and siding material. Unwanted heat gain can be greatly reduced by using light colored walls, and most housed in Village Homes use white or off-white for this reason.
The choice of roof color and materials also affects also affects heat gain. The houses in Village Homes use tile and shakes because they have proven to have the best thermal performance in tests carried out near Davis. Shakes and concrete tile remained the coolest of the six roofing materials tested. Light colored tile and shakes remained 40 degrees below light colored metal roofing or composition roofing on clear sunny summer day.
The final energy conservation measure involves tightening up the house, or weatherproofing it. This involves carefully sealing the many areas where unwanted cold or hot air can enter the house. This is important because in a well-insulated house, infiltration losses may almost equal conductive losses. The construction of the house must be done with an eye to reducing infiltration. The sills are set in mastic to reduce leakage under the walls. Caulking is done around doors and windows where cracks are left between the rough frame and the finished window or door frame.
After all these insulation features and considerations have been included in design, it is time to turn to another design consideration, using the heat of the sun to warm the house. To use solar energy effectively means taking advantage of the position of the sun. In summer, the sun is high in the sky and traverses an arc of 240 degrees from east to west. In winter, the sun is low and traverses an arc from east to west of only 120 degrees. The proper orientation of the houses in Village Homes maximizes heat gain in the winter while minimizing unwanted heat gain in the summer. A house that is longer east - west and shorter north - south with most windows on the south and a modest overhang on the south will receive full sun during the winter, yet be fully shaded during the summer.
The homes in Village Homes all have very few windows on the east and west sides where summer heat gain is the worst. The south side, in contrast, has many windows with overhangs or arbors to shade them in the summer. Arbors covered with deciduous vines are used often because they provide shade when it is most needed, the summer and fall. If springtime weather is cool, the leafing is delayed allowing the house to stay warm, while a warm fall will keep leaves on the vines, providing needed shade.
Passive solar homes are designed to store the sun's heat through the incorporation of high mass materials. The massive adobe walls of the old missions are a classic example of this principle. The adobe absorbs and stores heat and cool to bring the temperature extremes within the comfort zone. Other materials with the ability to store heat include water, concrete, stone, brick and tile. We have incorporated these materials in a variety of ways within the houses of Village Homes. Water is stored in water tanks camouflaged as walls, barrels or culvert pipes sealed at both ends.
A passive solar home not only stays warm in the winter, but is cool in the summer. South winds come from the ocean in Davis in the evening providing cool breezes cool nighttime temperatures. Homes are designed to ventilate well and the cool breezes cool down the thermal mass of the house. During the day, the house is kept tightly closed. The well insulated walls and ceilings keep the coolness inside. All windows are designed either with overhangs or shade screens to prevent the sun from providing unwanted solar heating. Most residents do not even have an air conditioner, saving seven percent on their overall family energy use.
Solar Water Heating
Five percent of the energy used by a typical Davis family is devoted to water heating, yet solar water heating can provide up to eighty percent of those energy needs. Solar water heating makes sense. It provides lower cost hot water, increases one's feeling of self sufficiency, and helps conserve needed high grade energy for more important uses. As Amory Lovins has said, "Heating water with electricity is like cutting butter with a chainsaw."
The solar water heating systems are installed along with reasonable water conservation measures. These include such inexpensive and readily available equipment as constrictors on the shower and water faucet, pressure reducers, aerators, better pipe insulation, and others. Strict application of all possible conservation measures can reduce hot water consumption to ten percent of existing use.
A poor refrigerator may use 200 kWh per month, and this can add 600,000 unwanted BTU's of heat to the house in the summer. Although it will help heat the house in the winter, using the refrigerator to heat the house makes about as much sense as burning down a house to stay warmer. An efficient refrigerator may use only one-fourth as much energy and will also reduce unwanted heat gain. It also helps to do without appliances that are not necessary, and many of the Village Homes residents have chosen to live without dishwashers, clothes dryers, garbage compactors, and other appliances which often provide very limited benefits at very high cost both in money and energy to purchase and operate.
Of all the energy consumed in the United States, nine percent goes toward food production. Large scale agricultural methods require the consumption of enormous amounts of energy. Large farm equipment used in planting and harvesting literally gobbles up fossil fuels. More energy is burned in transporting, refrigerating and packaging the foods. It has been calculated that the large scale methods of agriculture utilized in the United States require more energy than they produce. In other words, it requires more calories to produce a can of corn than you gain when you eat it. Obviously, this kind of inefficient production is going to see some drastic changes in the future. The home vegetable garden seems to be a new trend all over the country. It is a much more energy-efficient method of food production, requiring no automized harvesting, little packaging and no transportation.
Village Homes is located on some excellent agricultural land and we are taking maximum advantage of the fact. Seven acres of our land is set aside for small scale agriculture production. In addition, here and there we have excluded houses and planted a mini orchard. An almond orchard of 300 trees screens houses on the periphery of the development from a main road. There are common areas adjacent to every house which are often planted and maintained as a home vegetable garden. Several years ago we surveyed thirty-six potential homeowners and asked them what portion of their yard they would like to use for food production. Nineteen replied ten to forty percent and twelve said more than forty percent. They viewed the incorporation of agricultural land and the availability of vegetable gardening space as some of the most desirable features of the subdivision. We feel that if the greatest potential is realized, about ninety percent of the residents' fruit and vegetables will be grown within the subdivision. Some nuts, honey, poultry and grain are also produced within the community so that it might be possible to produce a quarter of the residents' total food requirements within the neighborhood, reducing energy required for food production by Village residents by one quarter.
In Village Homes we have incorporated a natural drainage system for runoff water to prevent the need for manmade, energy-consuming pumping systems. Drainage pipes have not been used in Village Homes. Instead, the subdivision is crisscrossed with small, creeklike channels which hold water and absorb it. These channels are landscaped as small creeks, are very attractive, and are a focal point of the greenbelts. The absorbed water is hopefully helping to replenish Davis's diminishing groundwater supply.
Creating a Neighborhood Community
A sense of community is an unknown in most of the recent suburbs and developments in America. Anonymous neighbors, fences and commuter jobs encourage the development of alienation and anxiety that threatens to corrode our society and greatly diminishes the satisfaction in many people's lives. One of the dominant factors in the design of Village Homes was a realization of the importance of community, and many features were included to encourage the development of a strong sense of community.
To establish this sense of community, people must know their neighbors, and they will get to know them only if they have reasons to get together. In Village Homes, we have made it easier by setting up common areas of greenbelts which are controlled by eight families, who were in most cases involved from design through to construction. After completion, most of the maintenance is also done by the cluster members. This has not always been easy for those of us unused to sharing responsibility, but it has been very effective in establishing community.
Working together on community projects has also been encouraged, both to reduce costs and let people get to know one another. Work parties have been held to build retaining walls, bridges, play areas, the pool complex, and community center. This has the added benefit of giving people the pride of ownership and has resulted in much better care and protection of community projects.
Village residents not only own a substantial amount of acreage in common, they also own some significant sources of revenue. Their income properties include ownership of ten apartment units within the subdivision and a commercial center (currently made up of small offices). The decisions which must be made about the uses of revenue and resources give community members more important reasons to come together as a group and provide money for the common economic and social welfare of the community.
Too much through traffic can disrupt and eventually destroy a community. Village Homes has very definite boundaries and internal roads are made up of long, dead-end cul de sacs. As the residents know each other, they can maintain careful watch on the street. This "defensible space" is a key element in reducing crime rates.
Finally, a community is weakened if most or all of the employment opportunities are outside the neighborhood. Village Homes includes several features to provide as many jobs in the community as possible. These include setting aside commercial space for community job development, agricultural areas for community farmers, and the greenbelts and community facilities that are maintained by members of the community, providing income for some residents. In addition, some of the residents work at home. Much more should be done to encourage professional workers to work at home most of the week.
We have found it very satisfying to live in a community where on an evening walk you can see and talk to your neighbors as they putter in their garden or walk and visit friends who are close and accessible.
The Success of the Village Homes Experiment
Several statistical studies have been performed by others, comparing Village Homes with other Davis neighborhoods. They indicate that we have begun to achieve those goals we originally set for ourselves: reducing energy consumption and creating a safe, satisfying community.
Dr. Janice Hamrin found that Village Homes residents consume half as much energy as those living in neighboring Davis subdivisions. This statistic is even more significant because the City of Davis has its own stringent, energy conserving building code and behavioral energy consciousness.
Statistics from the police department show that crime rates in Village Homes are ninety percent below those of other Davis neighborhoods.
The Village Homes experiment very clearly illustrates that substantial improvements can be made in patterns of development and building, while still working within the current institutional setting. Village Homes was constructed using conventional financing and building practices and conforming to current regulations, proving that it can be done.
We do not view Village Homes as an ideal. We see it as a practical step in the right direction. Just as houses and the quality of life within Village Homes have been improved as we have gained experience, we hope that future developments will be improved to become largely self-sufficient neighborhoods.
Most of the necessary techniques, equipment and knowledge are now available to do this. The challenge is to combine these many simple, practical, and economical steps so they work together and will meet the often archaic and illogical development and building codes. This will be easiest to do in a new development, but retrofitting existing developments should also receive more extensive consideration along these lines. In working toward becoming a more energy-efficient, healthier nation, we should be working on a comprehensive approach to increase the energy efficiency of our neighborhoods and communities. We feel certain that it is at this scale that the maximum can be accomplished.
Village Homes Bibliography
(A list of books which provide information about Village Homes)