With the current emphasis in MILCON projects being Sustainment, Restoration and Modernization (SRM) how can the need for adaptability, primarily related to new building design, be applied?
First, there is a lesson here about how important it is to design for future renovations similar to what is being done under the SATOC program. In most cases the same characteristics that make buildings adaptable are what wise clients look for in those scheduled for renovation, modernization or repurposing.
PREVIOUS APPROACHES
Historically, two somewhat radical approaches have been employed to achieve adaptive building status. The first is the temporary building, often used by the military when barracks and sometimes other building types were designed for limited life spans. The temporary building has become less favorable due to its level of sophistication and cost when compared against short life spans and early demolition.
The second approach to adaptable buildings is standardization. In the 1960s the School Construction Systems Development project (SCSD) funded by the Ford Foundation took progressive ideas in K-12 educational programming and combined them with standardized construction components to make it easy to build good schools quickly as demand expanded rapidly. The system was designed to maximize the ease of internal modification to changing enrollments and teaching needs.
SCSD, like the temporary building approach, was successful in some ways but was not a lasting solution to the issues of flexibility and adaptability. Its one size fits all approach had limited application due to locational factors, changing educational philosophies and technical advances combined with a lack of commitment to the system by clients.
CURRENT STATUS
We have accepted the idea that each building needs to be unique to its program and to fit reasonably into its context. Even when government agencies produce detailed programs and design guidelines, buildings often differ significantly from one to another. From the most general to the most detailed guidelines, there is seldom any guidance on how to design for flexibility and adaptability in the buildings we produce.
Yet we know a building’s structure and skin will outlast its original use by several times. This means major internal modifications and modernizations and eventually renovation of the building for a new use. Therefore, the wise client commits to making the building adaptable in the initial design phase.
IS ADAPTABILITY ACHIEVABLE?
Can a client design-in adaptability while providing for the initial program and working within the project budget? The answer is yes, if that client is skillful and committed to buildings as long-range investments. The result is a building with a longer life span and reduced overall costs.
Etegra has identified building characteristics that support these goals. They include the site and building configuration, building size, structural and mechanical systems. These parameters give clients a guide to design for future adaptation.
There are other factors that go into the design of a building or the selection of an existing building for acquisition. These factors, among which are location, context, architectural design quality, sustainability and construction cost, may be more important than adaptability. The objective then should be to include as many of the factors contributing to flexibility as possible while fulfilling the basic programmatic and design requirements of the project.
CHARACTERISTICS OF FLEXIBILITY AND ADAPTABILITY
These characteristics affect the potential for modification, adaptation and reuse of buildings. The relative importance of each is dependent on the intended future use.
Site: Level, open, with extra land area. Flat, open, regularly shaped sites can accommodate a variety of what might be required for a new use. Equally, if not more important, is a site that is perhaps 30 percent larger than what is required by the original program. Such a site can accommodate the unknown requirements of a new use and changes over time. Examples are building additions, increased parking, changed land use regulations and more rigorous storm water runoff and security requirements.
Access: Multiple points. Vehicular access from more than one point. It allows for the separation of parking and service access, two uses in the same building, or a secure and an unsecured entry.
Building Footprint and Configuration: Single story 30,000-ft2 rectangle. Having up to 15 percent more building square footage than needed is a bonus for future use and adaptation.
The greatest single characteristic of flexibility is having a single-story building. While this is not always an option, adaptation is complicated by additional stories. Note, however, that LEED as well as architectural best practice criteria favor multi-story buildings to promote energy and building material conservation.
A building with a rectangular footprint in about a 2:1 ratio is beneficial. Floor areas of 30,000- ft2 and a maximum of 50-ft from outside wall to the center of the building are preferable, allowing for daylight entry and views to the outside.
Structure: Steel with 30-ft bays and a generous floor to structure dimension. A structural grid with 30-ft bays and a 12-ft floor to bottom of structure avoids column conflicts and allows for above ceiling HVAC and data distribution. A steel structure provides adaptability and a capacity 10 percent above program requirements allows for additional loads such as special mechanical units, a green roof or a mezzanine. Minimizing the interior locations of shear walls and structural bracing increases flexibility substantially.
Consider building bays with 50-ft or greater column spacing in part of the building to accommodate unique future uses. In warehouse buildings consider going to 50-ft spacing throughout.
Floor to floor height in office buildings should be 15-ft to 16-ft and in warehouses 28-ft to 30-ft for good adaptability.
Exterior Walls: Non-load bearing masonry or metal panels over steel framing. Many military base buildings are pre-engineered steel frame with metal siding and pitched metal roofs. If designed without windows, be aware of vertical spacing between steel girts allowing window installation in the future.
When used, brick and block walls allow more flexibility than curtain wall systems. No more than 20 to 40 percent window area using punched openings is energy efficient and, if placed on a 5-ft planning grid allow for effective partition locations. Greater levels of openings may allow for effective daylighting design and/or lead to sustainability credits. There is a trade off between future programs, energy and construction costs that should be considered.
Energy: Extra mechanical and electrical capacity. Multiple air handling units are more flexible than central systems. Electrical power 20 percent above code requirements provides flexibility. Mechanical system capacity should also be 20 percent above initial needs. With variable volume systems this future capacity can result in substantial energy savings. In multi-story buildings, wet stacks with drains should be installed at 100-ft intervals for future use. Confirm that drain piping can be minimally sloped in the plenum to accommodate future plumbing requirements.
Space above ceilings should be 30-in rather than the minimum 18-in. This allows for practical and economic adaptation of systems. Extra space in electrical closets allows for increased electrical and communication capacity.
Data and Security: Allow for expansion. Recent experience reveals planning for increased data and security systems is critical. The 300-ft maximum run from server room to desktop computer will govern for some time and should be respected in locating server rooms. Provide server rooms or locations for them. Provide pathways for future fiber optic cable installation at least vertically between floors. Avoid small turning radii in pathways initially designed for copper cabling.
If future use requires building level pathways for cabling, to support building program including digital signage, conference rooms, AV, multiple desktops, security system closets (or locations) and lobby areas big enough for the installation of security equipment will be needed. Numerous entrances and doors may require security wiring in the future.
Floors and Roofs: Reinforced slabs or raised floors. Concrete floors with 6-in reinforced slabs allow for unplanned loads. Raised floors 6-in provide increased flexibility for power, data and special mechanical needs.
GOOD MATCHES AND LIMITATIONS
It is important to keep in mind that no building can be made adaptable to all future uses. Some building types are more adaptable to prevalent reuse types than others. The typical warehouse or large floor office building is the most adaptable.
Here are some adaptations or repurposing efforts that will work reasonably well:
- Warehouse (also big box retail or supermarket) to office, lab, R&D and possibly school or child care center. The larger the building the more costly the changes that will be needed to bring light and contact with the outside to the internal spaces.
- Office Building to lab, R&D or possibly school.
- School to office, lab or possibly R&D.
- Hospital and retail buildings have some adaptability (buildings originally designed for residential, entertainment or recreation may be limited to current uses).
CHOICES FOR THE FUTURE
During the design phase of a project a level of adaptability can still be achieved by making wise choices. Some adaptable features will cost little or nothing, while others will require more significant investment.
The right time to consider adaptability is during the master planning of base areas and during the programming and budgeting of MILCON or SRM projects. Setting 5 to 10 percent of the budget aside for future adaptability can accomplish the goal.
Generally, flexibility in the form of more site area, square footage and column-free area within the building provides adaptability. This margin for accommodating the unknown or the unplanned for is the key to the future reuse of most buildings. Recognizing and achieving this margin is the challenge that knowledgeable clients work to accomplish; they are concerned with the future as well as the present.
William Albinson, AIA, is Architect, Etegra Inc.; 314-533-2200 or by contacting Rebecca Thomas at rebecca.thomas@etegra.com.
