Sustainable Sites Initiative

©Designed by Conservation Design Forum, Elmhurst, IL www.cdfinc.com

Kresge Foundation Headquarters

Size & Type of Project:
2.74 acre corporate campus redevelopment; Greyfield

Location:
Troy, Michigan

Budget:
$1,116,000

Project Phase:

Completed in June 2005

Project Overview

The Kresge Foundation headquarters exemplifies one of the foundation's core values - environmental conservation - sustainable building practices, environmental stewardship and sound land-use planning, while inspiring grantees to incorporate sustainable building systems and healthy habitats into their own facilities. For the new headquarters (certified LEED Platinum), a compact building and parking footprint was designed to reduce negative environmental impacts. A historic farmhouse remains the cornerstone for the new building; other historic outbuildings were rearranged to maximize the site efficiency. The new building has green roofs that blend seamlessly with the adjacent landscape. Other portions of the building have white reflective roofs and harvest rainwater. The majority of site's open space is restored to native prairie vegetation and great care was taken to design a majority of workspaces to have views to this natural landscape - rather than the parking lots or collector roads that form the perimeter of the site.

Fortunately, the Foundation had the opportunity to explore strategies like green roofs, rainwater collection, porous pavements, and native landscapes. The combination of new construction, historic preservation, and landscape restoration provided an unusual mix of challenges resulting in a sustainable redevelopment prototype. The long-term potential for the Foundation headquarters goes beyond the restoration of ecological health on-site. It demonstrates the Foundation's mission to help create a sustainable future, and will inspire other adaptive retrofit projects to be more sustainable.

Site Context

The Kresge Foundation headquarters is located in Troy, Michigan, within the greater Detroit metropolitan area and the Clinton River Watershed. Troy is in the Southern Lower Peninsula, which is characterized by rolling moraines and flat lake plains. Historically, much of Southern Lower Michigan supported open oak savannas and prairies, which were maintained in a non-forested condition by frequent fires. Today, much of the region is dominated by agricultural and urban development.

Troy is warm during the summer with an average temperature in the 70s (Fahrenheit) and very cold during the winter with average temperatures in the 20s (Fahrenheit). Average daily temperature ranges from 25 to 75 degrees (Fahrenheit). Average annual rainfall for Troy is 33 inches. Rainfall is fairly evenly distributed throughout the year, with June being the wettest month.

The Kresge Foundation facility incorporates a historic farmstead that is surrounded by a mixed-use suburban landscape. Historic aerial photography and other records clearly illustrate the area surrounding the site was used for industrial agriculture until the late 1970s. At that time the adjacent properties were developed with office/commercial buildings and surface parking lots.

©Designed by Conservation Design Forum, Elmhurst, IL www.cdfinc.com

Sustainable Practices

Site Selection: For the Kresge Foundation, the first decision involved location-whether or not to remain on the present site or move to a new space. The Foundation explored a number of potential locations in the Detroit area, and ultimately chose to stay on its current property for a number of reasons: 1) the Foundation treasured the historic farmhouse, and wanted to remain caretaker of this valuable cultural resource; 2) the site could accommodate the proposed expansion; 3) the site was well-located for the current staff.

Integrated Design Team: Project decisions were approached as part of a whole, rather than piecemeal-beginning early in the planning stages and carrying through to completion. Design team members worked collaboratively, resisting formulaic isolated solutions. In doing so, they carefully considered the consequences of each aspect to achieve maximum efficiencies, especially in energy and water use. The iterative process included design charrettes, goal setting, and regular meetings. Team members and consultants included architects, landscape architects, contractors, and Kresge staff. Other consultants included civil, structural and acoustic/vibration engineers, historical preservationists, sustainability consultants and lighting and farmhouse-interior designers.

Minimize impacts during construction: Care was taken throughout the construction process to avoid site compaction and to protect existing trees. The contractor and the landscape architect worked together during the submittal process to meet rigorous topsoil and amended bioswale soil requirements, including specific ratios for sand, clay, and organic content, and seed certification to prove native origins. Preservation of several trees required prudent location of the building site, tree protection during construction, and on-going tree care such as root pruning.

Historic Structure Reuse: Existing buildings were reused to preserve cultural heritage and reduce waste. The historic farmhouse was restored and incorporated as a cornerstone of the new headquarters building. Other historic outbuildings onsite were refurbished, relocated, and merged into the new campus design.

Material Reuse: Because large portions of the new office building are embedded in the earth, the site relies on many retaining walls to address grade change. These walls were formed with gabion baskets-wire baskets filled with recycled concrete with a veneer of crushed granite. The retaining walls contain recycled concrete from the demolition of the former Kresge office building and parking lot, which spared this material from the landfill.

Protect and Preserve Vegetative Cover/ Reduce Urban Heat Island Impact: The vegetated portion of the site is 1.76 acres, or approximately 63.7 percent of the total site area (2.76 acres). This includes 3,200-square-feet of green roof on the new building, planted with a mid-range grass mix. The new building is stacked on two levels - one level above grade and one below. The green roofs are established on the first level and are even with the surrounding grade. The rooftop plants are rooted in 7" of lightweight growing medium, and 5" of granular drainage medium. The second-story roof surfaces have a high-reflective white material that reflects, rather than absorbs, sunlight to minimize heat pollution and provide a cooler surface to receive rainwater. Parking pavers are similarly light in color to minimize heat pollution.

Achieving Water Balance/ Rainwater Harvesting & Reuse: All the water needed for the landscape is obtained through direct rainfall collected from the site and the second-story roof. Rainwater is directed from the second story roof surfaces to the courtyard, and then piped to the constructed wetland where it is further cleansed, cooled and collected for reuse. The collected water irrigates the green roofs and supplies the wetland water feature with makeup water. When the wetland water surface rises more than a few inches, surplus water is drawn up into the cistern. If the wetland water level decreases by more than a few inches, it is topped off with gravity flow from the cistern. No potable water is used for irrigation purposes. (For comparison, a typical Midwestern office campus with turf vegetation would require irrigation at a rate of 1 inch per week [Source Purdue University, State of Indiana and US Department of Agriculture Cooperative].)

According to the project's water budget analysis, the average monthly water supply exceeds the average monthly water demand by more than 50 percent. During the growing season from March through September, approximately 22,000 gallons per month are used for green roof irrigation and to provide make-up water for the constructed wetland. The wetland has a vegetated aquatic shelf around the perimeter with native emergent wetland species that require a fairly constant water level.

Stormwater Management: The integrated stormwater management design treats water as a resource, allowing it to flow overland with ample opportunity to infiltrate back into the ground. All the stormwater that lands on the site is treated by the landscape systems; most of it is absorbed except in a rare extremely heavy rain event. The parking lot is constructed with a porous paving system that lets surface rainwater infiltrate into the ground. Surplus rainwater is directed to a bioswale system for infiltration; when the ground is saturated, the bioswales overflow into the city storm drain. Rainwater that overflows from the green roof and other portions of the site is directed to a constructed wetland pond developed on the lowest portion of the property. The wetland's water level and fringe habitat are kept fairly constant with water from the cistern, thus integrating the pond into the stormwater management system. Excess water from heavy rains is pumped from the constructed wetlands to the cistern and stored for supplemental water for green roof irrigation during droughts and make-up water for the wetland water feature.

Habitat Restoration: Approximately 64 percent of the total site area was restored to green space planted with ecologically appropriate vegetation, including more than 100 different adapted and native species. The entire ground plain has been established with a range of native and adapted grasses and flowering perennials that, once established, thrive without supplemental water, fertilizers, pesticides, or herbicides. Seed certification was required to prove native origins. The variety of plant material prevents a monoculture environment, attracts wildlife, and promotes biodiversity. The constructed wetland contains four varied vegetation zones, which enhance the diversity of plantings and fauna.

Human Health and Well-Being: The project's primary objective was to create an environmentally sustainable workplace that promotes the well-being and productivity of staff and visitors to the Kresge Foundation. All views from within the building are designed to provide a strong connection to the living landscape immediately outside the walls. Views from within the building capitalize on landscape features, especially the aquatic wetland, green roofs, and the central courtyard. The walking path and benches throughout the site encourage visitors and employees to enjoy the landscape and fresh air. An outdoor dining patio allows employees to relax outside during their breaks contributing to a healthy environment that minimizes stress.

Outdoor tobacco smoke policy: To protect outdoor air quality and the health of construction workers and the project team, smoking was prohibited on the site during construction. The site operates as a smoke-free campus.

Construction Cost

Total Site Costs $1,116,000.
In some cases, the best choice the team could make for the system as a whole involved leaving out a green strategy or technology. For example, the Kresge Foundation evaluated photo-voltaic panels and wind power. After considering that southeast Michigan is often overcast and that wind speeds are not predictable unless windmills are mounted very high, the project team realized that these technologies would have a high first cost and minimal long-term payback, so they were not included in the plan. In terms of site costs, it is difficult to quantify the value of some of the materials. For example, while the unit cost for bioswales and porous pavement are higher than conventional materials, their integration allows for the enjoyment of the entire site without a traditional detention basin. Also, some material costs reflect aesthetic choices by the client, such as the decision to line the gabion baskets with an ornamental granite stone, thus increasing the cost, not necessarily the function.

Monitoring Information

The total amount of water used outdoors has been estimated as 155,000 gallons/year. This assumes approximately 22,121 gallons per month during the growing season from March through September for irrigation for green roof plantings and makeup water for the constructed wetland pond. All of this is from harvested rainwater.

Maintenance

Kresge currently has a maintenance contract with the landscape contractor who installed the vegetative components of the project. Weed control and invasive species removal is part of the contractor's ongoing responsibilities, as well as replacement of unsuccessful vegetation and ongoing enhancement plantings. The site steward controls weeds through a combination of spot herbicide treatment, hand weeding, and mowing. The prairie planting is mown back to 4 to 6 inches in winter or early spring, followed by removal of the clippings. The landscape architect recommended that in April each year, the remaining plant stubs be burned with a propane torch. This application will further assure effective removal of cool season weeds and other undesired species. Eventually when there is enough fuel on site (grasses), fire management will be incorporated into the management regime.

Maintenance costs will be reduced over the life of the landscape since traditional turf mowing will not be necessary. Additional benefits include reduced environmental impact of gas mowers, and the elimination of noise pollution and soil compaction.

©Designed by Conservation Design Forum, Elmhurst, IL www.cdfinc.com

Issues/Constraints of the Site

• The design team specified a "topsoil weed seed treatment" that was not fully implemented due to conflicts with seasonal timing. As a result, weed seed in the topsoil was a major constraint that affected the restoration. A high level of weeds in the native zones required an intense period of weeding and spot herbicide treatment by the landscape contractor.
• Although limiting compaction during development was of utmost importance, virtually the entire project was impacted due to the site's compact size, and the existing structures that remained.
• The client needed to move offsite during construction, and thus had to move back into the facility before the site improvements and landscape were complete.
• Value engineering due to rising building costs scaled back site elements and postponed some landscape elements.

Lessons Learned

Working with local agencies and governmental bodies throughout the design process results in a favorable project. The City of Troy was an invaluable partner, bringing innovation to the project and approving its design, because it was interested in having Best Management Practices and Low Impact Development tools implemented within the city. For example, although the City building code required grass to be kept no higher than three inches, the project team was able to maintain the plan for natural landscaping and promote awareness of green practices within their local government, thanks to open communication between project architects and city officials.

Even though contractors and subcontractors with green experience were hired, regular communication and oversight was still required to ensure that appropriate sustainable alternatives replaced standard practices. The landscape architect established detailed specifications and a process for reviewing products and timelines to keep the project on track. The landscape architect also held regular construction site visits. Below are several examples of issues with installation and establishment practices for the site's created natural systems:

• Runoff from slopes with bare soil that was high in phosphorous ran into the wetlands and caused algae blooms. When the algae was removed, it was incorrectly piled on the shoreline to dry (a common beach-cleaning practice), where it killed some of the barely germinated shoreline vegetation. This led to another odd natural landscape problem. Because of the lack of shoreline grasses, dragonflies were unable to spawn on site and eat frog eggs, which hatched happily in the wetland. The resulting frogs -many, many frogs - were at first small enough to get into the new building.
• The entire site was weed whipped the first year rather than hand weeded as specified, and this may have reduced the ability of the native grasses to outcompete the annual weeds.
• During construction of the modular porous parking lot, a traditional approach to laying pavers on sand was used, rather than the specified materials. This traditional technique was detected by the landscape architect during a construction site visit, and the rest of the parking lot was later constructed using the correct specified materials, and therefore, the drainage system was not compromised.

It was critical to communicate the process of native landscape establishment and aesthetic considerations very clearly to the client and the design team so the expectations and design decisions were understood. Evolution of client staff and contractors over the length of the project posed challenges in keeping everyone educated. With any "green" project, efforts should be made to bring new participants up to speed with regards to the overall intent of the site systems and aesthetic expectations.

Across the design team, project champions stepped forward to remind the Kresge Foundation and public officials of the importance of green building. The owner is committed to sharing the experience to educate others on the pros and cons of green building.

More project details

www.kresge.org/content/displaycontent.aspx?CID=8 
www.cdfinc.com/

Project Consultants

OWNER:

Cynthia Powors
Office Manager
The Kresge Foundation

Owner Representative:
Ron Gagnon
Gagnon Consulting

PROJECT CONSULTANTS:

Landscape Architecture Project Manager:
Andi Cooper, RLA, ASLA
Associate
Conservation Design Forum, Inc.

Principal Landscape Architect:
David J. Yocca, RLA, ASLA, LEED AP
Senior Partner
Conservation Design Forum, Inc.

Water Resource Engineer:
Thomas Price, PE
Principal, Civil and Water Resource Engineer
Conservation Design Forum, Inc.

Additional Team Landscape Architect:
Marcus de la fleur
Conservation Design Forum, Inc.

Lead Architect:
Joe Valerio, AIA
President
Valerio Dewalt Train Associates

Architect Project Manager:
Dan Rappel
Formerly with Valerio Dewalt Train Associates

Civil Engineer:
Lee VanderMuelen, PE
Progressive AE

General Contractor:
JM Olson

Landscape Contractor:
WH Canon