318 Sentinel Drive

File Type: Free Content, Case study
Release Date: January 2005
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318 Sentinel Drive

*2005 Green Development Award Winner*

Fast Facts

Address: Annapolis Junction, MD
Company/Developer: Corporate Office Properties Trust
General Contractor: Clark Construction
Property Type: Office
Square Feet: 125,000 square feet
Height: 4 stories

Building Description: This building includes 31,000-square-foot floor plates, a precast and high performance glass exterior, and 37-foot clear span leasing bays, three elevators, and custom wood and specialty lighting in the lobby.


This Gold LEED certified project shows how green building can be profitable for developers and smart for tenants. Completed in March 2005, this four-story, 125,000-square-foot speculative office building was fully leased to a large, credit worthy tenant during construction.

Underscoring their commitment to green building, this property is among 14 other properties that Corporate Office Properties Trust (COPT) has registered in the LEED program.

A Model of Economic Sustainability

COPT considered both short-term viability and their market position over the long term in evaluating just how profitable the project would be. But they note “shareholders today are arguably more concerned with the short-term issue of our ability to provide their expected returns.”

Construction costs of $2.84 per square foot were offset by a $0.70 per square foot annual energy savings. To achieve an 11 percent unleveraged cash yield on cost, COPT needed to get an additional $0.31 per square foot in rent on an annual basis. The energy savings would produce a six-month return on investment.

Looking to the long term, the project is in a park that is a core COPT asset, so longterm ownership is all but guaranteed. The developer believes that green building will someday be the norm. Though the office market may not be entirely ready to make the leap to green, COPT sees an increased appreciation for the value that sustainable development brings.

COPT has developed an extensive set of guidelines for tenants, outlining not only the rationale behind green principles for interior improvements, but also offering recommendations, resources and definitions to help tenants create a healthy and comfortable environment.

Green Features

Sustainable Sites

  • Bicycle storage and changing rooms.
  • A storm water system that removes more than 80 percent of suspended solids and more than 50 percent of the average annual post-development total phosphorous.
  • A white roof to reduce heat islands.
  • Exterior lighting designed to prevent spillage beyond the site.
  • Tenant guidelines explaining the LEED program and encouraging green practices.
exterior view of 318 Sentinel Drive

Indoor Environmental Quality

  • Air quality monitoring to ensure safe levels of CO2.
  • Use of low VOC adhesives, sealants, paints and carpet and no urea formaldehyde used in the composite wood products.
  • A built-in walk-off mat system at entry and negative pressure in janitor’s closets to avoid dispersing chemical vapors.
  • Air filtration to MERV 13 level.

Water Efficiency

  • A landscaping irrigation system that employs sophisticated controls and other special equipment to use 50 percent less water than required by most systems.
  • Low-flow fixtures and dual flush toilets to reduce water use by 40 percent compared with typical buildings.
exterior view of 318 Sentinel Drive

Energy and Atmosphere

  • Demand-controlled ventilation, 100 percent economizer cycles and other features to deliver energy performance that is 40 percent more efficient than the level required by code.
  • Zero use of CFC-based refrigerants.

Materials and Resources

  • Diversion of 75 percent of construction debris from landfills to recyclers.
  • Recycling of more than 10 percent of used materials.
  • More than 50 percent of wood materials in construction grown in Forest Stewardship Council (FSC) certified, sustainable forests.