Manhattan’s Green Giant

Environmental building techniques define the largest commercial building being constructed in the U.S. and the first major office development in the revitalization of New York’s Times Square

by Daniel Kaplan, AIA
September 1997 Issue

Four Times Square, the first speculative office tower to be built in Manhattan since 1988, occupies a pivotal site at the intersection of Broadway and 42nd Street. Beyond embracing the essence of Times Square and meeting the complex needs of its corporate tenants, it is the first project of its size (48 stories and 1.6 million square feet) to adopt standards for energy efficiency, indoor ecology, sustainable materials and responsible construction, operations and maintenance procedures. This case study will reveal what lessons we have learned about applying environmentally responsible design, especially as it relates to speculative office development-and the implications for office building design in the future.

The building, located at the northeast corner of Broadway and 42nd Street in Manhattan, straddles several urban spaces with diverse identities -- the unfettered commercialism of Times Square, the urbanity of Bryant Park, and the composure of the midtown business district. The new 48-story office tower is designed with two distinct and significant orientations. The west and north exposures assume the character and liveliness of Times Square and are to be clad primarily in metal and glass with super-scaled commercial signage integrated into the facade, while along 42nd Street and the east facade a textured and scaled masonry treatment presents a more composed personality, appropriate to the corporate context of midtown Manhattan and the refined style of neighboring Bryant Park. This design, which celebrates the character of the city around it has received acclaim from both the general public and the design community. It has been called a "million and a half square foot building that everyone likes."

Throughout the process we have had the good fortune to be part of an extremely talented team. The developer, The Durst Organization, has lent vision and leadership to both the urban design and environmental thrusts. We have had a real partner in the Tishman Construction Corporation, the construction manager, and we have relied on the expertise of many organizations including Cosentini Associates, the project's engineer, the National Resources Defense Council, the Rocky Mountain Institute (RMI), Steven Winter Associates, Kiss + Cathcart Architects, Eley Associates. Ambient Labs and independent consultants Dr. Asher Derman and Pamela Lippe. This project has also received the financial support necessary to employ the most sophisticated computer technology for energy analysis -- the DOE-2 energy simulation modeling software- which was used as a primary basis for the selection of all HVAC and lighting systems, and exterior cladding materials and techniques. The DOE-2 analysis was performed under two grants: one from the Rocky Mountain Institute and one from the New York State Energy Research and Development Agency (NYSERDA).

Why Attempt an Environmentally Responsible "Spec" Office Tower

When thinking of green architecture, one usually associates smaller scale. Regionally inspired projects such as the Rocky Mountain Institute's home in Snowmass, CO. A 48-story, 1.6-million-square-foot glass and steel "spec" office tower bristling with super-scale commercial signage in the heart of Times Square is hardly the first image which comes to mind. It is a tribute to the efforts of groups such as RMl that we can begin to apply green principles to large scale commercial developments, and it is vitally important to do so.

Commercial office buildings have an impact on the environment proportional to their pervasiveness. Office buildings consume about 27% of the nation's electrical supply (Annual Energy Review, DOE, 1993). In the decade of the 1980s, approximately 5.3 billion square feet of office space was constructed in this country, the vast majority by developers. Tenants who lease space in their buildings are the large and small enterprises which comprise a vital sector of our economy, employing approximately 25% of the work force (Statistical Abstract of U.S.). Furthermore, with the well documented economic and population growth in Asia, the modern high rise office building is becoming a global reality. In short, this is where the action is.

Special Constraints of this Building Type

Two essential characteristics of Four Times Square had the greatest impact on the application of environmentally responsible design (sometimes referred to as "green" design): the vertical nature of the building and the economic constraints of the project, particularly those growing out of the developer/tenant dynamic.

A myriad of issues arise from the tall building type. Highrises, with their large core-to-wall depths and corresponding low ratio of perimeter envelope to interior space, create special mechanical and lighting challenges. There is a limited amount of roof space. There is an economic penalty for multi-story spaces, thick exterior walls and additional height. Energy and space are required for the elevators, without which the building cannot function. These conditions influenced the design process.

While highrise design precepts are somewhat familiar, the developer/tenant dynamic is not widely understood and warrants further explanation. Under the "spec building" construct, the often competing needs of the developer and the tenant have resulted in a design and construction process which is contractually divided into two camps: the "core and shell" (also referred to as the "base building") under the developer's purview, and the "tenant work" (also referred to as "tenant improvements" or "TIs") under the tenant's purview. In New York City this division is so extreme that the project proceeds with separate teams of design and construction firms, separate schedules and separate budgets. This division of responsibilities is not only limited to interior office planning but to the retail spaces and commercial signage as well.

This functional and contractual separation presents particular constraints in the design, construction and occupancy of an environmentally responsible project, most notably the ability to integrate and coordinate building systems for efficiency and comfort. For example, a proven approach such as simple daylight dimming must survive the following Byzantine line of contractual responsibilities between the base building architect selecting the glass and the tenant work engineer specifying the daylight sensors and ballasts:

1) Base Building Architect > Developer

2) Developer > Tenant

3) Tenant > Tenant Work Project Manager

4) Tenant Work Project Manager > Tenant Work Architect

5) Tenant Work Architect > Tenant Work Electrical Engineer

In developing the "green-ness" of Four Times Square, various strategies were employed that ran the gamut from working within the accepted status quo to reaching across the divide to educate and guide the building's tenants and their teams.

Specific Features of the Design and Process

The following descriptions of the salient features of the project are meant to be case studies illustrating the limitations and opportunities encountered in the process. This is not an exhaustive listing of all the green features of the building but rather the richest examples in terms of "lessons learned." They are presented by outlining the: 1) Objective, 2) Constraints, 3) Solution, and 4) Opportunities for Future Development.

Objective: To provide the greatest amount of daylight penetration into the space as possible, balanced with the need for high shading coefficient to minimize solar gain.

Constraints: Little control over tenant's selection of daylighting strategy, if any. No control over tenant's interior layout. Architect's intent to create a fairly monolithic appearance for much of the facade (i.e. a medium reflective glass). Light shelves projecting significantly beyond the building line would violate existing codes.

Solution: Since light shelves were a considerable expense to the owner for an un-guaranteed implementation by the tenant, they were discarded. The solution was a strategy of very large windows (7 feet high out of a 9-foot ceiling height) very high visible light transmittance glass (0.4 and 0.66) and a demonstration to the tenants (using DOE-2) of the savings resulting from daylight dimming. Approximately 25% of a given floor could be effectively daylit, with payback of 14 months. Architectural glass coatings are becoming more and more sophisticated, and the glass selected has a shading coefficient of 0.30 even with a visible light transmittance of 0.4 and 0.66.

Opportunities: A light refracting glazing or even a thin film located at the "transom" zone of the window, integral to the curtainwall and available at minimum expense borne by the building owner.

Objective: To provide energy efficient, low emission, CFC-free chillers for the heating and air conditioning system's central plant.

Constraints: Locate in building so that the plant's long fit-up schedule will not impact overall schedule. Traditionally lower floors, i.e. the cellar, are better.

Solution: Natural gas-fired absorption chillers/heaters located on the roof of the building. Due to the source fuel profile in the northeast, natural gas was selected instead of electrical and steam driven chillers. This decision follows the same rationale as The Audubon Society Headquarters and National Resources Defense Council Headquarters, both in New York City. The gas-fired plant was also more efficient, with a payback of approximately three years. It is important to note that the tenant benefits directly from the lower operating cost of this system. However, it is the developer who incurs the increased first costs, so it is false to speak of "payback."

While the roof is not the optimal place in the building for the central plant from a schedule point of view, this additional risk was borne by the owner because of their environmental commitment and the lower operating costs to their tenants. As a side benefit, the added weight at the building top acts as a "mass-damper," actually improving the structural performance of the building.

Opportunities: Not every developer has the same level of environmental commitment to make the up-front investment of a lower emission, more efficient plant. Indeed the vast majority of speculative buildings incorporate the most inefficient, lowest first cost systems. To insure that every future installation takes into account its impact on the environment, the environmental and architectural communities must push hard to institute some form of emissions-based legislation or incentives.

Objective: To minimize the amount of transmission loss and to offset the huge electrical load of the Times Square signage by generating electricity on site with fuel cells. Fuel cells are large natural gas "batteries" which generate extremely clean power on site via chemical reaction. No combustion is involved and the by-products are hot water and CO2. On-site generation is a worthy objective as little energy is lost in transmission as compared to a remote plant

Constraints: Finding a location in the building for the units. Each fuel cell requires approximately 700 square feet of floor space. No open land was available as the building is built up to the property line. It was not advisable to locate within the building as the units give off heat and CO2. The units need a major overhaul every five years requiring replacement of a 9,000-pound part. Once the units are turned on, it is inefficient to turn them off, but the building cannot use all of the power generated during very late night hours. Economic use of the excess power is an issue.

Solution: Eight, 200 kW fuel cells located on roof. Provisions for a maintenance crane will be built into the project to allow for replacement parts to be hoisted to the roof (700 feet above the ground). Yearly output of all eight units is 12 million kWh, approximately equivalent to the signage load. Payback is approximately 10 years, depending on gas prices. At this point the building team is struggling with how to use the excess power generated during the night. Discussions are ongoing with the utility and other energy services companies.

Opportunities: These units need to be made smaller, especially the required clearances (currently 8 feet all around). The weight of the replacement part needs to brought in line with standard service elevator capacities, about 5,000 pounds. Otherwise this technology seems ripe for general application.

Objective: To further offset the electrical load of the Times Square signage by generating electricity on-site with PVs. On-site generation is a worthy objective, as little energy is lost in transmission as compared to a remote plant.

Constraints: To achieve a reasonable payback, only integrated solutions, i.e. part of the building's skin, were ultimately considered -- the cost of the "replaced" area of the skin is credited to the cost of the PVs. Roof pave-integrated PVs were discarded due to the rolling loads of window washing rigs. The design of the upper, un-shaded portions of the building made for well defined areas where PVs would be acceptable architecturally: i.e. urban orientation, rather than solar orientation, generated the building's form.

Solution: PV's integrated into the spandrel -- the area of a facade between the top of one window and the bottom of the window above -- in a 60-foot-wide area at the center of each face, at the upper 19 floors of the building. The yearly output of the installation will be 48,000 kWh, about 1.6% of the base building load. A "thin-film" type of PV was selected because the paybacks were far better than the crystalline type. These would be laminated into tempered glass and structurally glazed into the facade. We are currently awaiting the results of structural tests and required city approvals.

Opportunities: A limited area of the facade was selected, since the design team saw

this as a demonstration of an untested application and wanted to limit the economic risks. If PVs were installed on all of the available spandrel area, the yearly output would have been 1.3 million kWh, or 50% of the base building load. If the use of building-integrated PVs is to mature to the level that installations of this scale are feasible, architects need to have the confidence in the economics of the system so they become an integral part of the design concept from the outset. For this to happen, the PV industry needs to become more like architectural glass suppliers, able to easily produce custom sizes and configurations easily and cost effectively.

Objective: Provide superior indoor air quality in the office spaces. Avoid sick building syndrome.

Constraints: Operable windows are not practical at building height (wind loads in excess of 60 psf), nor desirable from an energy standpoint. Developer could not force a "smoke free" building on the tenants. Tenant's finishes and furnishings are not under developer's control.

Solution: Outside air is ducted into building at high elevations (80 feet and 700 feet above the ground), avoiding as much street exhaust as possible. Outside air is filtered and monitored. Outside air is delivered to floors at 0.20 cfm per square foot, with an additional 0.05 cfm available at the tenants' discretion. There is additional capacity in the system to purge any three given floors simultaneously with 100% outside air. A dedicated exhaust shaft is provided for smoking and copy rooms. A network of tubes in the plenum allows for centralized monitoring of air quality. including tracer gas tests. The exterior wall is designed to allow for up to 30% relative humidity in winter, without the risk of condensation forming. Finally a set of tenant guidelines were written encouraging the installation of the most benign furnishings and finishes, and the building management has committed to using only low/no V.O.C. cleaning products.

Opportunities: With this design, we have probably reached the limit of the central air supply model. The next step would be to develop a "smart" operable window or a semi-permeable facade where an occupant could control the amount of tempered, outside air directly.

Objective: To achieve an integrated base building and tenant fit out in terms of energy efficiency, indoor ecology, sustainable materials and responsible construction, operations and maintenance procedures.

Constraints: The contractual and functional separation between the base building and tenant efforts as documented above. Tenants who were initially unaware of the benefits of environmentally responsible design.

Solution: Two strategies were employed. The first was educating the tenants' top decision makers to the benefits of green design. The architects conducted informational presentations to the tenants' senior executives and to the leadership of their design and construction teams, highlighting the environmental imperatives and potential economic benefits. Included were sample DOE-2 runs of their space, demonstrating the energy savings of various strategies. Key to this audience's 'buy-in" was communicating the spirit of the project. The second strategy was publishing a set of guidelines, written by the base building team, which illustrated ways in which the tenant fit out could take advantage of the building's infrastructure as well as various items for implementation independent of the base building. The guidelines were organized to address several audiences: the executive, the managerial and the technical readers.

Opportunities: The benefits of communicating the spirit of the project should not be underestimated. Architects are uniquely positioned to assume leadership in this area.

Making an Impact

In looking back on the process of "greening" this 1.8-million-square-foot speculative office building in midtown Manhattan, one conclusion can be drawn: although the constraints inherent in this type of project are great, the opportunities for making an impact are correspondingly great.

The biggest constraints we faced were economic and contractual, arising out of the developer/tenant construct. The best tools we had at our disposal to bridge this gap were: a) hard economic analyses, such as the DOE-2 runs, and b) leadership in educating the tenants and their teams.

While leading, cajoling, educating and pushing the tenants goes a long way, there is no substitute for concrete economic analyses in this era of bottom-line-driven decisions. For energy issues, the DOE-2 runs make a very believable case, providing the basis for payback or "rate of return" models; these resonate with decision makers. To demonstrate the value of interior environmental quality, fewer tools are available. (However, from a qualitative standpoint, rendering programs such as Radiance are helping considerably.) Since employee costs are an overwhelming proportion of occupancy costs, nothing would advance the cause of environmentally responsible design more than believable office worker productivity studies. To this end, the developer of Four Times Square has approached its two major tenants to participate in a productivity study. Since the tenants will be in their existing spaces for two more years while the building is constructed, this presents a unique opportunity for a "before and after" study. Other projects need to seek out similar opportunities so that there is a convincing body of evidence.

I'd like to conclude by acknowledging once again the vision of our client. The Durst Organization, who is leading the way in bringing environmental issues to the forefront of commercial real estate.

author’s box:
Daniel Kaplan, AIA, is Principal of Fox & Fowle Architects, P.C. in New York.

sidebar:

Tenants Follow Environmental Lead

To make sure tenants maintain the environmentally sound building practices employed in the base building of Four Times Square, the architects prepared a set of tenant guidelines encouraging the installation of the most benign furnishings and finishes and the building management has committed to using only low/no V.O.C. cleaning products:

Lighting

1. Partition layout concepts for maximizing daylight and minimizing artificial lighting

requirements.

2. Suggestions as to how lighting loads can be reduced to 1.0 watts per square foot from the conventional 1.5 to 2.0 watts per square foot.

3. Suggestions for more efficient lighting fixtures, fixture layouts, and reflective surfaces.

4. Technological data on sensors for controlling lights based on daylight, occupancy and design light levels.

Office Equipment

1. Data relating to computer equipment that meets EPA Energy Star specifications.

2. Suggestions as to how the plug load can be reduced to 1.0 watts per square foot in lieu of the conventional 4.0 watts per square foot.

3. Benefit analysis for use of occupancy sensors in computer screens.

4. A list of equipment and appliance top performers from the American Council for an

Energy Efficient Economy (ACEEE).

Interior Air Quality (lAQ)

1. Resource information on furniture, carpeting, materials and finishes relating to odor, fumes and VOC (Volatile Organic Compound) emittance and the use of non-toxic sealants, adhesives, sealers and finishers.

2. A listing of products for which healthier alternatives are available at comparable or near comparable cost. These include carpet and carpet padding, wall covering, paints/stains/finishes, adhesives/caulking/sealants, vinyl base, ceiling tiles, fabric, systems furniture, strippers and insulation.

3. Reference standards for all ventilation and IAQ.

4. Data on various sources of indoor air pollution such as smoking lounges, toilet facilities, janitorial closets, cooking facilities, parking garages, and reprographic areas. Recommendations on how best to exhaust the contaminants from these spaces using the building's direct exhaust shaft.

5. Recommendations relating to humidification levels, especially in winter months when low humidity can produce discomfort from dry skin and cause dust and other irritants to become airborne. Tenants are encouraged to take advantage of the thermal qualities of the exterior wall which allow the humidity to be maintained at a minimum of 30%. Reference standards provided for determining optimum conditions for the use of space.

Resource Conservation

1. Data provided on the availability of materials with recycled content. These include carpet and carpet padding, ceramic or glass tile, ceiling tile, wallboard, accessories, insulation, wall coverings, steel framing studs, flooring/wainscoting, moldings/decorative elements, furniture, fabrics, recycling containers, and partitions.

2. Tenants to be educated and encouraged to train their staff to utilize the recycling systems built into the project.

Construction Practices

Tenants to be encouraged to educate their design consultants, construction managers and subcontractors to follow the guidelines set forth for the environmentally responsible construction of the overall project, including a program of commissioning for verification of compliance with the DOE-2 energy simulation models offered to each tenant.

For more information on this or any article in Environmental Design & Construction, please contact Kristin Ralff Douglas at 415-863-2614 or krd@edcmag.com.

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