What would taller buildings mean for DC's architecture?
Would lifting the height limit lead to better architecture? It's not that simple, say architects. There are many people and forces, both cultural and economic, that shape the built environment, not just height.
Proponents of relaxing the height limit say that it would improve the quality of architecture, but they usually mean that new buildings will be less boxy if there's less pressure to maximize floor area. Yes, this might encourage more setbacks, deeper walls, more varied patterns, and richer textures. It might also lead to buildings that are just taller versions of the same boxes.
We asked several experienced architects to weigh in on the topic. Some oppose revisions and others support them. But they all note how aesthetics, human comfort, and building performance get trapped in between money and the law, and offer tangible ways to improve the urban environment with or without relaxed height restrictions.
Form follows finance
It may be helpful to think of a speculative office building as a machine for making money. In order to provide a very high level of service to a large amount of floor space, modern office buildings are packed with mechanical equipment and consist of highly engineered assemblies from structure to skin. We can see when money has been spent on high-quality finishes and beautiful details, but the real luxury is empty space.
Given the demand for space downtown, developers want to maximize revenue. The high rents enable them to finance the construction of multistory buildings to multiply the rentable floor area. In any location, physics, human needs, and legal restrictions constrain the design of buildings. Since you can't go beyond a certain height, there's a perverse incentive to use every square inch of the zoning envelope, an effect noted by several of the architects we asked.
Marshall Purnell notes that this pressure encourages facades with no depth. A four-inch-thick glass curtainwall assembly opens up a lot more space than a foot-thick cavity wall with insulation. Large windows can make smaller perimeter offices feel bigger. Flat and glassy looks modern, maximizes space, and carries a dubious aura of sustainability. It works well enough for owners, but produces a thin public realm.
Matt Bell of Perkins Eastman notes that the worst offenders in terms of boxiness suffer from bad proportioning and composition. Relatively modest setbacks and architectural texture, combining patterns, recesses, and different materials, can make a world of difference. The Investment Building and 1999 K Street both show how minor massing details can significantly diminish bulkiness.
Left: Photo of 1999 K Street NW from Jahn Architects. Right: Investment Building by NCinDC on Flickr.
In order for greater height to enable better architecture, it would have to change the value proposition of those architectural features. Niches reduce revenue and flexibility, so there is a disincentive to use even little recesses for office buildings. With less of a need to maximize every square inch, developers might agree to increase the facade depth and reduce setbacks. The equation for finishes and detail, which cost the same amount for each floor, would remain unchanged.
Revised limits could make for more sustainable interiors
Robert Peck, who works on office design at Gensler, notes that the height limit contributes to "unusually low ceilings" in Washington. Buildings, he argues might be more efficient with higher floors to let light penetrate deeper into the building. Light enters a window at an angle, so a ray entering higher up goes deeper, especially if it can be reflected with a light shelf.
Shalom Baranes argued a related point a few months back: greater floor-to-floor heights allow ducts to be more efficiently shaped and routed. The efficiency of ducts depends on the directness of the route and the ratio of duct surface to volume. A circular or square cross section is best. But in cramped ceilings, flattened ducts and circuitous routes require air to move at faster speeds. Not only does this waste energy, it's noisier.
Section through One Bryant Park, showing floor heights from CookFox Architects.
I'd also add that higher floor heights allow heat to move away from human bodies. Designers can further this by distributing air through the floor and returning it through the ceiling. Because the fresh air does not mix with the stale air, lower volumes of air can flow at slower speeds and warmer temperatures and still achieve the same level of thermal comfort. And there are still further techniques that can be used when ceilings are less congested.
Interestingly, these requirements suggest that building height might be better regulated by the number of floors, rather than by absolute height. The cost of higher floor heights would remove the incentive for outrageous floor heights in most cases, while reducing the pressure on building systems. Traditionalist architect Lťon Krier has argued that this produces building heights that vary within certain limits, with extreme differences uncommon.
We could shape the height and density
None of the architects support unfettered height increases. Cities are more than just economic engines. Land use is deeply intertwined with transportation, community, and aesthetics, and the purpose of planning is to balance those interests to produce a thriving city. It's in the city's interest to promote a public realm that benefits citizens.
The official statement of the DC chapter of the AIA calls for "A thorough, in-depth study," of the city's height limit, arguing that "well-designed, taller structures will provide an interesting counterpoint and add visual interest and variety to the skyline." The authors, David Haresign, Mary Fitch, and Bill Bonstra, have been working with the Office of Planning and the National Capital Planning Commission to discuss ways of managing the height limit.
They argue that the rationale behind the 1910 law is outdated, so new regulations that reflect modern building standards and aesthetic needs should be the beginning of any conversation. Outside of areas with federal interest, they point out that the DC government should be the organization to determine those needs.
Even if Congress were to change the height law, it would require revising DC's Comprehensive Plan, last changed in 2006. Roger Lewis, architecture columnist for the Washington Post, echoes the DC AIA's call for detailed planning. An insistence on transparent planning, he argues, is the best way to ensure equitable outcomes for a growing city. Analysis of geographical information could enable an approach that replaces a one-size-fits-all approach with one that carefully tunes height for livability.
The city might also look for more specific ways to shape the city's architecture. David Varner of SmithGroup points out that the comparative devaluation of existing buildings could lead to premature teardowns. To prevent this, he suggests a transfer of development rights system, where property owners could sell the windfall development rights to other landowners to offset the costs.
The District could offer height in exchange for design review or mandate a set of design codes in exchange for greater height. Architect Travis Price looks to incentive zoning, allowing buildings to reach higher in exchange for architectural features. Combined with setbacks, buildings in his imagining would reach into the sky with sculptural features most analogous to the towers and setbacks of One Franklin Square, although he'd prefer to do without symmetry.
Even without a formal system of incentive zoning, the regulations could be better tailored to architectural content. The NCPC's modest revisions allow people to occupy penthouses, currently used mainly to store mechanical equipment, and at best hidden by a setback. This might encourage more exciting roof structures, adding interest to DC's skyline.
Architecture isn't determined by economics alone
Residential blocks, the other major kind of multistory building, face slightly different restrictions. Zoning is more restrictive than the height limit in most places. Revising the height limit wouldn't have an effect on the sense of the city for many years. Before any changes actually happen, there will be time to fine-tune plans and settle on an effective regulatory method. DC will never look like Manhattan.
Defenders of the Height Act accurately say that the current law has benefits, such as encouraging developers to build to the lot line. We are fortunate that the height limit discourages the shattered streetscapes of some cities. But it's a side effect of a rule that has many negative side effects, namely increased cost of living. If the city needs strong streetwalls, then those should be required. If a low roofline gets more sun to the streets, then regulation based on solar exposure would be more precise.
The height limit, as it is currently structured, is too crude of a tool to encourage the built environment most people want. Horizontally, the building regulations may permit too much, but vertically there's no flexibility. A careful revision of the height limit could resolve much of the blockishness of DC's architecture, but absent more effective guidelines, there's no guarantee the public realm will reach a higher quality with more height.
One thing the architects reiterated is that good design requires clients to desire it. As Marshall Purnell notes, his ability to realize good design depended on having the good fortune to find clients who want it. No matter how talented an architect is or how much design review there is, the quality of the environment depends ultimately on an owner's desire to contribute to the public realm.
To read the full comments of the architects, click here.
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