| General Information |
| Location |
 |
Annapolis, MD |
| Owner |
|
The Chesapeake Bay Foundation Inc. |
| Architect |
|
SmithGroup, Inc. |
| Engineer |
|
SmithGroup, Inc. |
| Completed |
|
December 2000 |
| Building Use |
|
Commercial office, interpretive center |
| Size |
|
32,000 SF |
| Stories |
|
Two |
| Cost |
|
$7,500,000 (excluding land cost) |
| Occupancy |
|
Typically occupied by 80 People, 40 hours per week |
| Relevant codes |
|
International Building Code
International Energy Conservation Code |
|
Mixed Mode System |
| Mixed Mode Strategy |
|
Changeover system. Temperature and humidity
sensors located on the exterior of the building determine when the climate
is appropriate for natural ventilation. Upon sensing optimal conditions
the building management system turns off the mechanical heating or cooling
system and turns on modified exit lighting fixtures which notify the building
occupants that it is ok to open the windows. Simultaneous to this change
mechanical operators open the windows in the clerestory above the second
floor to allow a natural draft to begin. Air is then pulled in though the
operable windows, rises through the building, and exits through the clerestory. |
| Natural Ventilation Details |
|
Operable windows on the north (leeward)
side of the building are larger than those on the south (windward) side,
to promote greater air velocities inside. Inlet windows total approximately
495 ft2, while outles total approximately 822 ft2. There are a combination
of lower windows that can be operated by the occupants, and upper clerestory
windows that automatically open. |
| HVAC System Details |
|
Geothermal heat pumps with a desiccant
dehumidification system are used for heating in the winter and cooling
in the summer.
There are two ventilation fans in the east portion of the building to assist
the natural ventilation flow in areas obstructed by the mechanical room
and restrooms. The air enter enters on the east and is exhausted on the
north. The fan sizes are 6500 cfm (1st floor) and 2800 cfm (2nd floor),
providing an estimated supplementary air change rate 1.025 air changes
per hour. |
| Configuration & Control |
|
The building is arranged in an open plan
office with the whole of the office space utilizing the mixed-mode strategy.
A total energy management system monitors and controls energy use in the
building. The system alerts employees when windows should be opened. Other
windows are opened and closed automatically. The system also monitors daylight
levels, adjusting electric lighting as needed.
There are approximately 60 individual controls for the windows. On the
south façade, windows are banked together in groups of four. Hand
cranks by Clearline are mounted on the first floor of the building. They
operate both the lower windows and another set approximately 15 ft. high.
Rain sensors are located on the mechanically opened clerestory windows
set to automatically close when wet weather arrives.
As of December 2001, the building setpoints were:
Nat’l Vent’ Available between 61-72°F.
Window use is up to discretion of occupants. Assist fans may or may not
be turned on.
Assist Fans Off when indoor temperature < 68°F. On when indoor temperature > 72°F.
Summer Cooling Between 77-78°F.
Humidity is controlled to 50% with a 10% range.
Winter Cooling A/C or NV used when indoor temperature > 81°F. System
turned off when indoor temperature < 78°F Humidifcation off when
RH > 68%. Humidification turned on when RH < 50%. |
| Building Design Process |
| Time Line |
|
1997-2000 |
| Design Tools |
|
The U.S. Green Building Council's LEED
Rating System was used in setting goals for the project before the design
commenced. Benchmarking tours of other green projects and CBF's educational
centers were influential in the design. A peer review of the concept design
was organized by the Sustainable Building Industries Council (funded by
the Department of Energy) and included reviewers from the Maryland Energy
Administration, Maryland Department of Natural Resources, World Wildlife
Fund and National Renewable Energy Laboratory. An integrated approach to
design was used, and in-house engineers worked closely with architects.
Air flow predictions made with simplified rules-of-thumb from ASHRAE Handbook
of Fundamentals. |
| Energy Analysis |
|
Designing Low-Energy Buildings with Energy-10
(DLEB/E-10) software was used for energy analysis. The initial design projection
that the building would run in natural ventilation mode for 9% of the year
was found to be actually 25% of the year after monitoring the building
for several seasons. |
| Commissioning |
|
Project commissioning was provided by SmithGroup,
Inc. the designers of the building rather than an independent third-party,
as Commissioning Agent. As a result, the contractor felt that the Commissioning
Agent could not be a neutral arbiter. The mixed-mode component was one
of the easier parts of the commissioning process. The architect credits
this to the simplicity of the mixed mode system as compared to the daylighting
and water collection/treatment systems which were more complicated and
required changes and adjustments during commissioning. |
| Code Conflicts |
|
The need to naturally move air from the
first floor up to the second floor and exhaust through the roof when windows
were open required special consideration due to required fire and smoke
separations. To accommodate this, the architects worked with the fire Marshall
to install a laser-beam detection alarm in the air slot connecting the
two floors triggering the building fire response if smoke was detected
moving through the building. |
| Other Design Issues |
|
Due to a relatively low design fee available
for the design of the building the architect wasn’t able to perform
a full CFD study of the natural ventilation, a process they normally require
to confirm intended design performance. Luckily, due to the excellent historical
weather records collected at the nearby lighthouse, enough climate data
was available to satisfy the designers that simple natural ventilation
rules of thumb would result in a well-ventilated building. |
| Building Performance |
| Outdoor Air/Noise |
|
Due to the relatively small building footprint
on a 32-acre site, outdoor noise and air pollution are not a concern. |
| Occupant Satisfaction |
|
The University of California Berkeley Center
for the Built Environment performed a web-based occupant indoor environmental
quality (IEQ) survey at the Chesapeake Bay Foundation. The survey addressed
general building satisfaction, general workspace satisfaction, office layout,
office furnishings, thermal comfort, air quality, lighting, views, acoustic
quality, cleanliness and maintenance, and several other functionality issues.
Occupants reported being satisfied or very satisfied with all categories
but with more neutral comments in thermal comfort and acoustic quality.
Thermally responses showed that occupants often find the building too cool
in both warm and cool weather. This dissatisfaction was attributed to a
lack of accessibility and control of thermostats as well as stratification
of warm air to the upper floor and certain rooms that then result in discomfort.
Acoustically the responses showed that the open plan cubicle workspaces
were not providing enough privacy for occupants both between cubicles and
between the open first and second floor. |
| Actual Energy Data |
|
Annual purchased energy use: |
Fuel |
Quantity |
Mmbtu |
Kbtu/ft2 |
Electricity |
313,000 kwh |
1,070 |
33.4 |
Natural gas |
34,500kwh |
118 |
3.68 |
Fuel oil |
0 |
0 |
0 |
Annual on-site renewable energy production |
Photovoltaics |
2,140 kwh |
7.3 |
0.228 |
Solar thermal |
41,000 kwh |
140 |
4.37 |
Total annual building energy consumption |
Total purchased |
|
1,190 |
37.1 |
Total on-site |
|
147 |
4.6 |
Grand total |
|
1,330 |
41.7 |
Annual end-use breakdown |
Heating |
34,5000 kwh |
118 |
3.68 |
Cooling |
64,100 kwh |
219 |
6.83 |
Lighting |
106,000 kwh |
362 |
11.3 |
Fans/pumps |
1,100 kwh |
3.75 |
0.117 |
Plug/equip |
105,000 kwh |
358 |
11.2 |
Unspecified |
|
273 |
8.52 |
Source: DOE high performance building database |
|
| Additional Building Features |
| Sustainable Sites |
|
• South-facing exposure.
• Takes advantage prevailing winds for natural ventilation.
• Minimizes heat island potential through landscaping and exterior
material choices.
• Minimizes light pollution by using timers on exterior lights. |
| Water Efficiency |
|
• Composting toilets.
• Water-efficient appliances.
• Native landscaping.
• Captures and reuses rainwater.
• Uses bioretention filter to treat oil and other pollutants in runoff
from the pervious parking area.
• 90+% reduction in water use over an otherwise comparable conventional
office building. |
| Energy and Atmosphere |
|
• Maximizes daylight with large windows,
clerestories, and an open interior design.
• Each workstation has a motion sensor that shuts off computer monitor
and task lighting.
• Luminous sensors control overhead lighting.
• Photovoltaic panels on south wall.
• Solar hot water panels on the roof.
• South façade shaded with large slotted wooden structure,
allows winter sun, keeps out summer sun.
• Interior blinds on west, south and east facades. |
| Materials and Resources |
|
• Began with "cradle-to-cradle" philosophy
(consider what materials can be made into at the end of their useful lives).
• Deconstruction, rather than demolition, of existing structures on
the site; all materials were auctioned, salvaged, or recycled.
• Materials with recycled content (i.e., galvanized siding made from
cans, cars, and guns; interior fabrics; and rubber flooring).
• Materials from rapidly renewable or regenerable resources (i.e.,
cork and bamboo flooring).
• Structurally Insulated Panels (SIPS) in roof and walls.
• Parallel strand timber beams.
• Local sources (over 50% of materials came from a 300-mile radius). |
| Indoor Environmental Quality |
|
• Natural ventilation is used whenever
possible.
• CO2 monitor and automatically controlled operable windows.
• VOC-free paints.
• Natural, non-toxic materials (i.e., cork, linoleum, bamboo). |
| Project Team |
| Architect |
|
SmithGroup, Inc.
Washington, DC
http://www.smithgroup.com
|
| Commissioning & Mechanical Engineer |
|
SmithGroup, Inc.
1825 Eye Street NW, Suite 250
Washington, DC 20006
202-842-2100
http://www.smithgroup.com
|
| Interior Design |
|
SmithGroup, Inc.
1825 Eye Street NW, Suite 250
Washington, DC 20006
202-842-2100
http://www.smithgroup.com
|
| Civil Engineer |
|
Greenman-Pedersen, Inc.
10620 Guilford Road, Suite 100
Jessup, MD 20794
410-880-3055
http://www.gpinet.com
|
| Structural Engineer |
|
Shemro Engineering, Inc.
6902 West Ave
Bethesda, MD
|
| Landscape Architect |
|
Karene Motivans
PO Box 29
Shephardstown, WV 25443
|
| Leed Coordinator |
|
J. Harrison
Architect
Annapolis, MD
|
| Computer Energy Modeling |
|
National Renewable Energy Laboratory
1617 Cole Blvd.
Golden, CO 80401-3393
(303) 275-3000
http://www.nrel.gov
|
| Contractor |
|
Clark Construction Group
7500 Old Georgetown Road
Bethesda, Maryland 20814
(301) 272-8100
http://www.clarkconstruction.com
|
| Additional Information |
| Awards |
|
• USGBC LEED v.1 Platinum Rating
(2000).
• ASHRAE Technology Award in 2001 (National Capital Chapter 1st Place
Award in the Commercial New division).
• AIA/COTE Top Ten Green Projects in 2001.
• Business Week/Architectural Record in 2001.
• AIA Washington, D.C. Chapter in 2001 Award for Excellence in Architecture.
• NESEA Green Building Awards in 2003 First Prize: Places of Work.
• Building Design & Construction Magazine in 2001 Grand Award,
Building Team Project of the Year. |
| Sources |
|
• U.S. Department of Energy High
Performance Buildings Database
http://www.eere.energy.gov/buildings/highperformance/case_studies/index.cfm
• Case Studies of Naturally Ventilated Commercial Buildings in the
U.S., Jui-Chen (Roger) Chang, M.S.M.E. thesis, Massachusetts institute
of Technology, June 2002. |
| Contact |
|
Primary Contact
Greg Mella, Architect (Project architect and publicist)
SmithGroup, Inc.
Washington, DC
greg.mella@smithgroup.com
http://www.smithgroup.com
|
