Germán Saavedra Prado, miembro del Ejército colombiano

The choice of an appropriate building site is an important decision in cre- ating a sustainable library. Several criteria should be considered in choosing the site. How will library users get to the site? Will it be by car, bus, or by walking in the neighborhood? Sites that require that all patrons arrive by car represent less sustainable options than sites that are well served by bus, light rail, and other forms of public transport. In many suburban communities, where there is no practical alternative to driving to the library, the site should be close to other destinations such as supermarkets, drugstores, and schools, so that single-purpose trips can be minimized. Future demographic trends should be considered. Many formerly central libraries are now inconveniently situ- ated. The creation of smaller neighborhood branches, especially in established pedestrian-oriented areas, should be considered. With the increasing use of computer networks, these local branches serve many of the same information needs as regional branches. Even smaller information stations, located in malls and in major shopping districts, can provide library services with minimal in- frastructure requirements.

Adaptive Reuse Versus New Construction

Cities and, increasingly, suburban districts are filled with derelict and under- used buildings that could find new life as libraries, often at substantial cost sav- ings over new buildings, and with the environmental benefit that substantially fewer resources are required for rehabilitation than new construction. Some of the most successful public libraries are found in converted commercial lofts, city halls, and even large houses.

It is important that a potential structure be carefully analyzed before any de- cision to reuse it is made. Among the questions to be asked are the following:

• Does the building allow for an efficient layout of program spaces, both cur- rent and projected?

• Is the structural system capable of supporting book stacks, typically de- signed to carry 150 pounds per square foot, or compact shelving, which can weigh up to 300 pounds per square foot?

• Will the structure readily accept conduits for wiring?

• What is the condition of the existing heating, ventilating, and air- conditioning (HVAC) system? If it needs to be replaced, are ceiling heights sufficient to add supply and return ductwork?

• Are electrical, plumbing, telecommunications, and other services ade- quate, or will they need to be upgraded?

• What is the condition of the building shell? Will significant restoration or replacement be required?

• Are there any potential environmental problems on the site such as as- bestos, PCBs, mold, or other hazards that will require potentially expen- sive remediation?

• Is there sufficient area for parking?

• Is the building in a secure neighborhood that will be viable in the long term?

Even if substantial rework must be done to an existing structure, it may still be more economically and environmentally beneficial than building a new building. Also, many older buildings are in central, desirable locations, close to public transportation and other amenities.

Demolition and Recycling of Existing Buildings

Even if it is not appropriate to save an existing building on a proposed li- brary site, environmental and economic benefits can be derived by recycling and reusing as much of the old building as possible, as opposed to carting the entire building off to a landfill. Many parts of a building can be recycled, in- cluding steel, aluminum, glass, and certain forms of asphalt, bricks, and stone. There is a developed secondary market for architectural ornamentation, hard- ware, fixtures, and fittings. Rather than hand these potentially valuable items

over to a demolition contractor, owners may wish to work directly or through a broker with recyclers and resellers.

Site Planning and Landscape Design

Once a building site has been selected, the orientation and shape of the building must be determined. Proper orientation toward the sun and prevailing winds can have a significant impact on energy usage over the life of the building. In a rectangular building, it is preferable for the long axis to run in an east- west direction. This is because it is more difficult to control east light in the morning and west light in the afternoon than to control north and south light, which trace symmetrical arcs through the day.

In cool and moderate climates, southern sunlight can help to heat the build- ing during the colder months but is undesirable during the warmer months. Be- cause the sun is lower in the sky in the winter than in the summer, sunscreens can be designed that allow low winter sunlight to enter the building but reflect summer sunlight (see fig. 3.1). In hot climates, direct solar heat gain into build- ings is rarely beneficial, so limiting the amount of south- and west-facing glass and screening windows with porches, verandas, or awnings is desirable. In hot climates, making a building more compact will lessen the amount of surface area through which heat will penetrate. Direct penetration of sunlight onto collec- tions can also lead to deterioration caused by ultraviolet radiation.

Site microclimate can be adversely affected by the creation of large, un- shaded heated surfaces, or heat islands. Heat islands raise ambient air tempera- ture. Heat-absorbing surfaces include large expanses of flat roofing and asphalt roads and parking lots. Large surfaces of asphalt, concrete, and other imperme- able materials also disrupt natural site drainage and can require expensive engi- neering solutions to channel water away from the library. Trees should be used to shade parking lots. Permeable materials such as gravel should be considered as an alternative to asphalt. Parking lots should be broken down into manageable areas, and site drainage should be allowed to follow natural courses.

Prevailing wind direction also affects building energy usage. Unshielded winter winds infiltrate buildings and increase winter heating requirements, but in the summer months, operable windows can take advantage of cooling breezes, thus lowering summer cooling loads. Orienting buildings to capture prevailing breezes in temperate and hot climates can lower mechanical cooling loads.

If possible, the site should connect to a system of walking or biking routes separated from automobile traffic. A bike rack should be placed near the main li- brary entrance, and biking to the library should be encouraged as one of the most environmentally sustainable forms of transportation.

Library landscaping should be designed to minimize the need for artificial ir- rigation. In hot and dry climates, drought-tolerant plant materials should be used. Designers should specify native materials that have evolved along with the regional climate and require less care and upkeep. The landscape design should consider the preservation and even reconstruction of animal habitats. There is

growing interest in the design of constructed wetlands in place of traditional re- tention basins. Though more complex to design and construct, these wetlands can function as viable ecosystems with genuine biological diversity. Such ele- ments can also help to support the educational mission of the library.