Historic preservation conserves resources and encourages sustainable design, making it an environmentally friendly approach to revitalizing a community. Historic structures also tend to be more pedestrian-friendly than modern structures, which increases the walkability and vibrancy of a community.

Resource Conservation and Sustainable Design

Preserving and rehabilitating an existing historic building has less negative impact on the environment than new construction. The rehabilitation of older buildings utilizes existing infrastructure, such as water lines, sidewalks, and streets, and preserves existing building materials and architectural elements. Debris from demolition typically makes up 25 to 30 percent of all materials discarded in landfills. The rehabilitation of an existing structure prevents substantial amounts of building material from becoming landfill. The economic revitalization of a historic main street lessens the demand for another strip mall on the edge of town.

Historic buildings, particularly vernacular designs, are by nature closely tied to the land and are often compatible with the principles of today's sustainable design for environmentally friendly structures. Features of historic buildings such as porches, large windows, and projecting overhangs take advantage of natural ventilation systems and solar heating. Historic properties typically incorporate the use of shade trees in their setting and are often sited to take advantage of natural wind currents. Preservation encourages the use of natural materials, typically generated at the local level.

Conservation of Embodied Energy

Historic buildings embody energy that was expended in the past — the energy put forth to make the bricks, clapboard siding, windows, and other elements of the building. Rehabilitating older structures is a cost-effective reuse of these existing assets. If original elements are removed and replaced with new materials, new energy must be applied to make them. On the heels of the energy crisis of the mid-1970s, the consulting firm Booz Allen Hamilton measured the amount of energy inherent in various building materials. They found that the amount of energy required to manufacture eight bricks, haul them to a construction site, and place them in a wall is equal to the amount of energy in a gallon of gasoline.

This finding was important because it tells us that existing historic buildings — the heart of many communities' Main Streets and neighborhoods — represent a huge energy investment. This investment is lost when these buildings are torn down. For example, the amount of energy inherent in the bricks alone in a typical three-floor, 20-by-100-foot brick bearing-wall main street building is equal to the amount of energy in more than 3,700 gallons of gasoline — enough to keep the average American driving for almost eight and a half years. Multiply this by the structures that make up a downtown or city residential building stock, and the embodied energy is enormous.

Increased Walkability

Historic preservation increases the general walkability of a city, town, or village. Historic structures were built and designed with pedestrians, rather than automobiles, in mind.

Historic commercial buildings, and many historic residential buildings, were built up to the sidewalk. Unlike their modern-day counterparts, historic commercial buildings have large display windows that passersby can see through, and their entryways are designed to be inviting to pedestrians. This welcoming design  encourages interaction, and the more "walkable" a downtown or commercial area is, the more active and vibrant it becomes. And when people can take a pleasant walk to their destination, they may just leave the car at home.

• The Economics of Preservation: Tourism and Jobs
• Smart Growth Community Planning