Colorado Real Estate Journal -
The market for speculative office buildings has been virtually dead for the last four years, so “mixed-use” projects over that time have largely been euphemisms referring to apartment buildings with ground-floor retail. But it appears that the office market is recovering nicely, and it is likely anticipated that office building construction – even speculative buildings – will begin to pick up in 2013 and 2014. Given the fact that very few office buildings have been built in downtown Denver over the past decade, the question is: What criteria must a Class A (or AA) building meet nowadays? At Davis Partnership Architects, we believe these are some of the important considerations: Planning Factors: • 40’ to 47’ depths from the core to the perimeter walls are ideal in terms of floor plate efficiency. Smaller tenants work well in depths of 35’ to 40’, but there is typically a reduction in rentable efficiency with these reduced depths. While the trend in Europe and in “boutique” offices, in the U.S. it is definitely toward smaller office depths (typically 30’ or less), overall efficiency and cost considerations are motivating most American office developers to maintain greater depths. • Floor plates in the Denver market should ideally range in size from 20,000 gsf minimum, to generally 30,000 sf maximum. Floor plates larger than 30,000 sf can be tremendously efficient for large single-tenant users, but require special attention in planning and design if they are intended to be used as multitenant floors. • For any size of floor plate, multi-tenant floor configurations require a great deal of study to ensure an efficient corridor scheme can be developed which meets new code requirements regarding exiting. Consideration of average tenant size, and an understanding of the optimal placement of tenants on larger floors is critical, particularly for floors in excess of 25,000 square feet. Since the Denver Amendments to the International Building Code preclude the use of the typical floor Elevator Lobby as part of a “Z-Corridor” configuration, this puts more emphasis on core planning to arrive at efficient multi-tenant corridor layouts. • Efficiency of the floor plate is critical, in terms of maximizing rentable and usable areas. Since larger shaft sizes reduce rentable area, consideration must be given to every strategy that has the potential to minimize the number and sizes of shafts through the building. • A dedicated service elevator should be provided in buildings larger than 250,000 sf. For buildings where the top floor is more than 120’ above grade, the code now requires a dedicated “Fire Service Access Elevator Lobby” of minimum 150 sf on each floor above grade, with direct access to the Fire Service elevator and also direct access to one of the stair enclosures. This new code requirement is a major driver of the planning of high-rise building core configurations. • Interestingly, a host of significant new code requirements now apply to buildings more than 420’ in height, requiring an additional exit stair, along with more stringent fire-proofing and fire-suppression requirements. These new requirements will severely constrain the development of new office buildings taller than 30 stories. Marketability Factors: • A 5-foot planning grid is customary in Class A buildings. Ideally, perimeter columns should be spaced at 30’, so they synchronize with either 10’ or 15’ wide offices. • 9’-6” ceiling heights are becoming the expected standard at typical tenant areas. However, many of the sites where new buildings will be developed have strict height limits, which will drive the need for tighter floor-to-floor heights in order to maximize rentable area. This requires creative design solutions to minimize plenum heights and structural depths. • Consideration of views is always exceptionally important. In response, we encourage extensive use of high performance vision glass – with at least some areas of floor-to-ceiling glass expanses. • We try to avoid extensive areas of punched windows, which typically require a 10’ grid in planning, and are not sufficiently flexible to accommodate office widths of 15’. • Elevator service is critical, and more sophisticated controls may now be employed to improve service. These new controls, often referred to as “Destination Dispatch,” are effective on banks of 6 or more elevators, but have little impact on banks of 4 cars or less. • LEED Gold certification appears to be the desired market standard for Class AA buildings. For downtown sites with great access to public transit and surrounding development, LEED certification is not prohibitively expensive. Arriving at an economical yet highly energy efficient mechanical system is always a key issue. • Lighting of tenant spaces is increasingly important. As the industry quickly moves to more energy-efficient lighting solutions, adaptability of lighting to incorporate future conversion to LED sources is critical. While seldom a Class AA building standard today, linear pendant fixtures are increasingly used in tenant areas to allow more efficient and user-friendly lighting schemes. Also, because pendant lighting is not recessed above the ceiling, it may allow higher ceilings within the allowable floor-to-floor heights. • While under-floor air systems are becoming increasingly common, their use in office projects has mostly been limited to build-to-suit projects, or projects where an anchor tenant shapes the building system selections. The majority of the tenant market appears to be more comfortable with overhead VAV distribution, at least for now. • Condenser water loops serving the full height of the building are important to allow tenant-installed supplemental cooling units for computer rooms and also potentially for after-hours HVAC use. The condenser water loop can also be important in providing cooling to street-level retail spaces, without needing to locate large air-handling units in the lower section of the building. Office Buildings are too often thought of as “simple,” probably because the tenant spaces are not fully designed and finish at the outset. But, on the contrary, we find there are tremendous challenges and rewards in designing truly intelligent, state-of-the-art office properties that meet the needs of today’s and tomorrow’s tenants.