Celebrating the Power of the Sun: Creating the first

Celebrating the
Power of the Sun:
Creating the first designed
Zero Net Energy Building
for theCommonwealth
of Massachusetts
By: Peter Shaffer, AIA architect /principal DiMella Shaffer
Client
Commonwealth of Massachusetts - Deval Patrick, Governor
Department of Capital Asset Management - DCAM
User Agency
North Shore Community College - Wayne Burton, President
Designing buildings which are capable of generating a quantity of clean, renewable energy equal to the amount
of energy being consumed by the building is not a new concept. Known as Zero Net Energy Buildings (ZNEB),
there are quite a number of smaller (mostly residential) structures that have successfully achieved this noble goal.
The challenge becomes much greater as the size and the program complexity of the building increases. Add to
that the need to create a building which is developed within the public sector, thereby requiring competitive
construction bids, and the odds are against success. North Shore Community College (NSCC) under the umbrella of
its public development agency the Department of Capital Asset Management (DCAM), with the help of its architect,
DiMella Shaffer and construction manager, Walsh Brothers Construction, beat the odds. As of January 2012,
after two years of construction, The Commonwealth of Massachusetts proudly announced that it
opened its first 58,000sf institutional building designed as a Zero Net Energy Building. So how did this
happen?
In 2006 the Boston/Seattle architectural firm DiMella Shaffer was hired by DCAM to conduct a planning study for
NSCC to consolidate the College’s health professions programs, formerly divided between NSCC’s main campus
and the adjacent former campus of the Essex Agricultural School, into a new Health Professions Building containing
classrooms and laboratory spaces dedicated to courses in nursing, physical and occupational therapy, radiology,
respiratory and surgical care, and animal science.
The proposed site located strategically in the center of campus was also ideal for the creation of the College’s new
student services center to house student enrollment and student support services including facilities dedicated to
counseling, advising, tutoring and testing. The creation of a joint Health Professions/Student Services Building was
a natural choice.
Photo: Solar canopy entrance promenade
Solving the programmatic needs of the college was critical to NSCC’s President, Wayne Burton, but even that was
not enough to satisfy his vision. “As an educational institution, we have an obligation to be a regional leader in many
ways, and one is to make sure that we teach our students by example, such as by how we are actually behaving.
So when we urge them to think about conserving our resources, we have to be doing the same thing.” Burton
challenged the design team to design a ZNE Building and committed himself to do whatever he could personally do
to obtain financial support from the State to ensure that NSCC’s new Health Professions/Student Services Building
would become the Commonwealth’s first project celebrating Zero Net Energy.
Having previously worked with DCAM and the State’s Community College system, DiMella Shaffer was not new to
the design of sustainable, energy efficient buildings within the public sector. Earlier in the year, the firm designed
a classroom building for a sister community college, Cape Cod, DCAM’S first project in the Commonwealth to be
awarded a gold certification level under the United States Green Building Council’s (USGBC) Leadership in Energy
and Environmental Design (LEED) program.
Photos: Photovoltaic panels / On-site electrical production
Health professions nursing classroom
The Right Timing, The Right Collaboration
Most “first” achievements have several factors that are working in their favor. As the design of the Health Professions/
Student Services Building was progressing, Governor Deval Patrick, in association with the Massachusetts State
Department of Energy (DOE), was promoting green building construction and was looking for an opportunity to
develop the State’s first zero net energy building. The Governor’s Council on Sustainability selected three model
projects of which North Shore Community College was one. As of this date, it is the only demonstration project
whose design has met its original goal and, after one full year in operation, we anticipate that the building
as designed is actually operating to the targeted ZNEB level. Through added encouragement by President
Burton and DCAM the State eventually added approximately $2 million more in funding to augment the original
construction budget thereby enabling the building to be constructed to a stringent ZNEB standard, in addition to
the more achievable LEED Gold standard. According to the New Buildings Institutes March 2012 Research Report, at
58,000 sf, NSCC is the fourth largest ZNEB to become operational in the United States.
The Challenge
Within DCAM’s project budget of approximately $24 million, the design of the new building had to meet all of the
College’s programmatic requirements while also incorporating as many design elements and systems that would
enable it to be sustainable and meet at least LEED Gold requirements. Given the above stated financial cap, it soon
became obvious to all stakeholders that the College needed to look carefully at controlling its “wish-list” of programmatic
desires and make necessary compromises to reduce the building’s square footage to be as small as possible. The
eventual required size of the building settled at slightly less than 60,000sf. A standard LEED Gold building could be
built within this budget, however, in order to achieve the desired ZNE Building, additional funding sources would need
to be secured. Design progressed with the understanding that the availability of additional funding sources might not
be known until well after the construction drawings were completed and the public construction bids were eventually
evaluated. Flexibility within the public construction bid documents became an added challenge and, moreover, a
necessity. What did this mean?
Photo: South Courtyard Student Services Building
Making a Building Energy Efficient and Achieving ZNE
There are three basic design strategies to incorporate when designing an energy efficient building. These include:
1. Maximize the use of natural daylight which will greatly reduce the need for electrically produced artificial light.
2.
Minimize energy loss and heat gain by designing the “tightest”, most energy efficient exterior building envelope.
3.
Reduce energy usage by specifying and using only ENERGY STAR equipment and incorporating only highly efficient
mechanical and electrical building systems.
If these design strategies are strictly followed it may be possible to offset the calculated electrical needs of the building with the
production of an adequate on-site renewable energy source, assuming that sufficient financial capital is available.
The Process: The Basics
Balancing the required size of the building with the project budget allocated by the State was critical in helping to
guide the design team to identify options that the College and DCAM needed to consider in their quest to achieve a
sustainable building.
It is generally understood that the most effective approach to achieving a ZNEB goal is to minimize the heating and
cooling loads within the building. Every opportunity to do this must be fully explored. The design team studied the
options for the building’s orientation to the sun, the effectiveness of the insulation quality on the exterior enclosure,
and alternative mechanical and electrical building systems. In order to minimize energy consumption even further, the
design team also needed the commitment from the College to minimize plug load requirements by requesting only
electrical power sufficient to operate electrical equipment that was crucial to the learning/teaching experience. The
design team recommended foregoing the typical “energy contingency cushion” often included as part of a traditional
programming process. Managing the total electrical design loads was a critical component in the team’s determination
to develop the appropriate size of the electrical system.
Photo: “free” daylight
Daylight can most easily be controlled on the north facade of a building where the sun does not shine or along the
south façade where the sun is typically highest in the sky. For this reason, a majority of the public areas, classrooms
and offices take full advantage of these north / south orientations. East and west exposures were minimized making
sun control a relatively minor concern.
To enable daylight to penetrate deeper into the interior of the building, the design incorporates a continuous
clerestory in the roof that welcomes, reflects and directs sunlight, glare-free, into the third-floor main corridor and
then down through floor openings illuminating the second-floor corridor below. Internal offices and conference
rooms aligning these corridors are often glazed to allow them to benefit from this “shared” daylight, deep within
the core of the building.
The Process: Controlled natural daylight and monitored artificial lighting
Since artificial lighting and the need for its associated cooling can often represent approximately 35-40% of a
building’s total energy consumption, great effort was spent to reduce and minimize the need for electric
lighting by capitalizing on the benefits of “free” natural daylight. This resulted in significant energy savings
Two existing
Buildings
especially when dimmable lighting controls are introduced. For this building it was shown through building energy
modeling that electric lighting energy savings achieved by using natural daylight far outweighed the savings from a
Courtyard
potential alternative reduction in window area or incremental improvements in enhanced window glass performance.
The shape and positioning of the proposed building was carefully studied to maximize the utilization of daylight.
The rectilinear-shaped building, with its long axis running in the east-west direction, maximized the length of the
south façade which most benefits from the rays of the sun. Fortuitously, this positioning also created ideal physical
linkages to the adjacent two existing buildings thereby helping to create a south-facing landscaped courtyard to
encourage students to enjoy the surrounding nature, as well as a “green roof” that serves as a unique horticultural
learning environment.
Site Plan
Solar
Canopies
Health Professions / Student Service Building
Photos: South courtyard / connecting paths to two existing buildings
Second floor corridor daylight well from clearstory above
Classrooms and offices which face south are protected from direct sunlight and glare by a combination of external
and internal light shelves, horizontal devices that shade, reflect and redirect natural sunlight coming through
fenestration openings. These light shelves improve occupant comfort by controlling glare and reducing high-lighting
contrast on interior surfaces. They also allow light penetration deep within the interior of the space, often increasing
daylight by a factor of two when compared to windows without the benefit of light shelves. This reduction in the
need for electric artificial lighting greatly reduces the overall electricity requirement for the building. Using the sun
as a managed light source is the most efficient way to illuminate a space, as it requires no electricity.
The design of the electrical lighting within the classrooms and larger office areas was sequenced in zones parallel to
the exterior wall so that selected lights can be automatically dimmed by sensors in response to available daylight levels
which vary throughout the day. Vacancy sensors also automatically turn off lights when the rooms are unoccupied.
A combined use of these automated sensors further reduced the need for electricity resulting in energy savings as
much as 20-25% relative to buildings without such controls.
Photo: External light shelf
Photo: Internal light shelf
The Process: Natural daylight versus a super-insulated building
There exists a very delicate balance between designing a building with lots of windows to take full advantage of the
benefits of natural daylight (reduction in the need for artificial light) while at the same time minimizing the heat gain/
loss through the opaque exterior building envelope (maximizing exterior insulated wall construction).
For instance, by utilizing computer modeling it was determined that incorporating a continuous roof-top clerestory
window greatly reduced the additional electrical lighting loads which would have been necessary to artificially
illuminate the third and second floor corridors. Even though this additional clerestory glass lowered the insulation
value that would have been achieved had a solid well-insulated roof been provided, the additional electrical energy
required to provide artificial lighting without a clerestory far exceeded the energy needed to offset the added heat
gain/loss through the preferred clerestory glass.
The NSCC Health Professions/Student Services Building is well insulated achieving high R (resistance) values for its
roof and walls. R-values of 45 for roof and 20 for walls were achieved. Similar to the clerestory at the roof, increasing
the insulating R-value for the exterior walls is easy to achieve if one reduces the amount of glazed vertical wall
area. Reducing window area, however, will correspondingly reduce daylight which will result in a significant
increase to the electrical loads required to supply appropriate lighting levels. Computer modeling allowed for studying
options which ultimately resulted in recommending an appropriate percentage balance between a well insulated
opaque exterior building material (approximately 59%) and a less insulated, transparent/translucent glazed enclosure
(approximately 41%). Maximizing the “free” lighting benefits of this daylight system in combination with light
sensors to activate and control the artificial lighting was critical to enabling this NSCC building to reduce its total
electrical load to approximately 15% of total electrical energy requirements versus a more common 35% contributing
factor. The actual kWh of energy associated only with the internal lighting for this building turns out to be only
one-third of what would be expected for more conventional buildings.
Section
Photo: Continous clerestory provides daylight to 3rd to 2nd floor corridors
Renewable Energy Production On-Site
While the building envelope and mechanical/electrical/plumbing (MEP) systems can be designed to be as energy
efficient as possible, a critical challenge in a ZNEB design is how to best develop and incorporate into the architectural
solution an on-site means of producing renewable sources of energy. Wind turbines were considered but were
quickly eliminated as not a feasible application for this project. With limited land area, the most viable option for
NSCC was to explore the generation of electricity using photovoltaic (PV) cells located on the building’s roof. Energy
modeling consultants, Buro Happold Consulting Engineers and Solar Design Associates, confirmed that properly
designed roof mounted PV panels would yield the highest production of electricity if properly tilted towards the sun
with minimal shadows cast on the photovoltaic surfaces. Consideration was initially given to also integrating PV cells
onto the vertical surfaces of the building’s southern façade, but analysis confirmed that the electrical yield would be
much lower than a comparable cell area devoted to the roof. Eventually it was determined that approximately 1088
solar PV panels would be required to produce the 340kw of energy that was required to meet the energy needs of
this building in this particular location. It was also known that these panels would only be considered if the State
decided to adequately support this demonstration effort with an additional $2 million in funding. So what to do?
The Process: High-efficiency mechanical and electrical systems
In keeping with President Burton’s challenge to reduce the College’s dependence on fossil fuels and create a true
building demonstration project, a highly efficient geothermal heat pump coupled with a chilled beam system
was selected to heat and cool the building. This proven technology, which uses the temperature of the earth instead
of fossil fuels for heating and cooling, has been successfully employed in Europe for the past 15 years. Although
some consideration was initially given to utilizing a more conventional fossil fuel boiler/cooling tower to augment the
geothermal system, eventually it was determined that if the number of geothermal wells could be increased by only
15% to a total of 50 wells each at a depth of 500 feet redundancy would be created without the need for reliance on
fossil fuels, with the exception of emergency back-up. To further minimize electrical consumption, wherever possible
ENERGY STAR rated equipment was specified and utilized throughout the building.
Additional Engineering Facts
A. Primary heating/cooling system consists of
D. Plumbing systems include grey water systems
F. Shading cast from the truss mounted, solar
four heat pumps and energy recovery
units to recover heat energy from the
return air stream to preheat outside air.
B. Active chilled beam technology resulted in
lower fan energy consumption.
which uses rain water to supplement potable
water use in toilet applications.
E. High performance lighting fixtures and
LED lighting decreased the electrical
consumption.
PV roof panels hovering above the roof,
known as cool roofs, contributed positively
to a decrease in the heating and cooling
loads on the mechanical systems.
C. Radiant heating/cooling system was used
selectively in appropriate building areas
Photos: Daylight illuminates Student Servives portion of the building
Photovoltaic Panels mounted to custom steel truss
North Shore Community College’s Photovoltaic Array
There was no doubt that the design team could design a building that would be able to fulfill the project’s 58,000sf
program scope requirements as well as design the building to the desired minimum LEED Gold standard. However,
there was no assurance that additional funding would be designated to allow the project to fulfill its ZNEB objectives
which presented a major challenge.
The exterior and interior of the building had to appear finished and fully designed whether or not the additional
grant money came through from the State to achieve a ZNEB. The architects concluded that the only reasonable
approach to this design/financing problem was to treat the potential inclusion of a rooftop photovoltaic
design solution as an “additive” element to the design of the building which would be viewed as visually
successful regardless of the ultimate financing outcome.
In the event that the public funding for these photovoltaic panels did not materialize, the Health Professions/Student
Services Building would still be built to the level of LEED Gold but would forgo meeting the Zero Net Energy Building
challenge. Fortunately, the funding did materialize, bids were competitive, and the ultimate integration of the
panels into the building’s design helped the completed project to visually “celebrate” its on-site electric energy
generation. (see “Ready to Reality” for a more detailed discussion of the evolution of the photovoltaic rooftop design)
Photos: Photovoltaic solar panels intergrated into architectual design “celebrate” on -site electric energy generation
In Conclusion
The question that has often been asked is “How did NSCC achieve the design and construction of the Commonwealth
of Massachusetts’ first Zero Net Energy Building?”
It was not because the design team incorporated exotic and expensive design processes or systems to achieve these
ends. Rather, the techniques had been used in one form or another in other buildings and were carefully analyzed
and selectively incorporated and integrated into the NSCC building as deemed appropriate. In addition, only with
the help of a State funding program, designed to encourage and foster sustainability in State owned properties, was
President Burton’s ZNEB challenge finally realized.
Basic principles for designing this sustainable and energy efficient building were followed and included:
1. 2.
3.
Designing the building envelope to be as energy efficient as possible while balancing this objective with maximizing
the amount of controlled natural daylight to help in the reduction of supplemental electrical lighting.
Incorporation of proven, energy-efficient technologies into the mechanical and electrical systems utilized to operate
the building.
Incorporation of a system of solar electrical production panels were integrated into the building’s architectural design
so that in the event a separate funding source could be found the design of the building could easily be transformed
from Zero Net Energy “READY” to an actual Zero Net Energy Building.
Photo: Student Services optional entry
ZNEB : “Ready to Reality”
The Photovoltaic Journey
A.
It was determined that approximately 408 megawatt hours (mwh)/yr of electricity would need to be produced on-site in
order to off-set the building’s anticipated usage of electricity during one year. These calculations were already anticipating
that some portion of the building’s roof surface should be reserved to erect a clerestory which would introduce daylight
into the center of the building, helping to reduce the electrical energy associated with artificial lighting.
B. To achieve this goal it was determined that a 340kw solar photovoltaic (PV) system would be necessary. Assuming the solar system
utilized the most efficient panels available on the market, such as SunPower’s E19 series 318W, then 1,088 such panels
would be required at the slopes and orientation established by the preliminary design. If such a system could be incorporated
onto the building to meet the projected loads, then NSCC would become The Commonwealth’s 1st Zero Net Energy Building.
C.
In 2011 when this project was constructed, manufacturers of solar photovoltaic systems produced PV panels rated at
250-320 Watts of electricity per panel, with a range from 7% to 18% efficiency in converting sunlight energy to electricity. It
was determined that somewhere between 1,000 and 1,100 panels would be required to achieve the stated goals. To determine
if the roof of the proposed building had sufficient horizontal roof area to support the required number of panels, several
options were evaluated. First, the electrical output of panels mounted flush to the flat roof (0 degrees tilt) was studied.
These panels, assuming no spacing between the panels, required a total roof surface of 25,000sf. To make this a realistic
solution a roof surface of approximately 28,000sf was required. A second alternative was to try panels tilted 10 degrees
toward the sun to maximize the electrical output of each panel. Taking into account spacing between the panels to minimize
shading effects from one panel to the next, a total roof surface of 34,000sf was required. Since the available square footage
of the main rectangular roof was only 21,000sf, it became clear that a new challenge was at hand. The following design
solutions were studied:
Photo: Main Entrance
Health Professions / Student Services Building
1. Build the smallest enlarged horizontal roof, extended and cantilevered over the existing roof structure, to
3. Construct a continuous sloping roof plane or metal steel frame at approximately 27 degrees to the horizontal
support the required number of photovoltaic panels on a total structured area of 28,000sf. This challenging
structural solution appeared to result in a financial burden to the project that would most likely exceed
the $2 million anticipated grant. Such a solution would also tend to conceal the solar panels that were
actually providing the on-site electrical generation and would also cast shadows on the vertical window
surfaces from the cantilevered roof above. This solution was rejected.
2. Tilt the individual photovoltaic panels and mount them to the cantilevered horizontal roof frame thereby
increasing their electrical output per panel. Panels would have to be spaced sufficiently apart from each
other to avoid shadows cast from one panel onto the next. The area of the horizontal roof would be
approximately 34,000sf and the dripping of rain, snow and ice from the open cantilevered steel frame was
problematic. Visibility from the ground toward the panels was only slightly better than the previous
scheme. This solution was rejected.
4. Construct open steel roof trusses at a set angle above the roof and mount the individual panels spaced apart
Diagram 1 Diagram 2 roof plane and mount the panels onto this ideal electrical generation sloping plane thereby reducing the
number of total panels required for electrical production. Such a solution would result in a sloping plane
on the roof which rose from 2 feet above the roof at the south edge of the roof to approximately 45 feet
above the roof at the north edge of the roof. Collecting and removing rain, snow and ice from the sloping
surface is problematic. Architecturally this was unacceptable and would also be cost prohibitive.
from each other. This would allow water and snow to drain onto the roof but would result in the required
sloping surface to be larger than the previous option. Such a design solution would be visible from the ground
and thereby “celebrate” the on-site production of electricity. This solution had great promise.
Diagram 3 Diagram 4
Photo: Daylight illuminated stairs encourage circulation while providing “free” light”
5.
5. Experimenting
Experimenting with
with aa combination
combination of
of angles,
angles, aa final
final compromise
compromise design
design solution
solution was
was reached
reached whereby
whereby the
the
7. Because each of the three pre-qualified solar panel manufacturers produced panels which yielded different
size
size of
of the
the truss
truss would
would slightly
slightly only
only overhang
overhang the
the size
size of
of the
the building’s
building’s roof
roof thereby
thereby minimizing
minimizing shadow
shadow
inefficiencies
inefficiencies while
while still
still allowing
allowing for
for water
water and
and snow
snow to
to drain
drain onto
onto the
the roof.
roof. Sufficient
Sufficient electrical
electrical production
production
was
was yielded
yielded with
with aa combination
combination of
of steel
steel trusses
trusses built
built with
with aa 77 degree
degree top
top chord
chord tilt
tilt with
with panels
panels mounted
mounted on
on
aa purlin
purlin system
system fastened
fastened to
to the
the top
top chord
chord of
of the
the truss
truss at
at an
an additional
additional 22 degrees
degrees angle
angle for
for aa total
total of
of 99
degrees
degrees tilt
tilt from
from the
the horizontal.
horizontal. This
This solution
solution appeared
appeared to
to be
be the
the most
most promising.
promising.
6.
6. To
To accomplish
accomplish the
the necessary
necessary flexibility
flexibility required
required to
to accommodate
accommodate the
the public
public bid
bid process,
process, the
the structural
structural steel
steel
trusses
trusses were
were fitted
fitted with
with aa steel
steel purlin
purlin system
system that
that in
in turn
turn allowed
allowed for
for standard
standard manufactured
manufactured solar
solar panels
panels
to
to be
be mounted
mounted onto
onto each
each manufacturer’s
manufacturer’s standard
standard track.
track. This
This system
system allowed
allowed for
for competitive
competitive bids
bids to
to
proceed
proceed knowing
knowing that
that the
the successful
successful manufacturer’s
manufacturer’s standard
standard product
product would
would be
be able
able to
to be
be supported
supported
and
and accommodated
accommodated on
on top
top of
of the
the building’s
building’s pre-designed
pre-designed truss/purlin
truss/purlin system.
system.
electrical production capabilities, it was necessary to devise a design that could be easily and successfully
modified to allow for the incorporation of additional panels should the successful low bidder potentially
require more surface area to meet the level of electrical production performance.
8. The final solution provided three to five ground-mounted steel canopy structures strategically located in
the parking lot along the primary pedestrian path. These supplemental structures allowed for a slight
increase in the total number of solar panels to be added, if necessary, to fulfill the electrical production
performance requirements from a very competitive bidding entity who might be proposing utilizing a
greater quantity of less efficient panels for consideration. After the bids were analyzed it was determined
that SunPower had proposed the most cost effective solution for NSCC with three site canopies being
included in the final design providing the required number of their panels to achieve the stated electrical
performance output.
Diagram 5 Photo: 3 site canopies help to augment rooftop PV panels to achieve electrical performance output
DiMella Shaffer is thankful for the opportunity to work on such an important
project and is grateful to President Burton and Governor Deval Patrick for their steadfast
commitment to sustainable design. This groundbreaking project, the first designed
Zero Net Energy Building in the Commonwealth of Massachusetts, creates a place of
opportunity that fosters collaboration and enables and celebrates discovery. This
unique and important building accomplished what it set out to become – a place of
community where the College can shape the global citizen and create leaders that
will meet tomorrow’s sustainable challenges.
Photo: A total of 1088 photovaltaic solar panels produce 408 megawatt hours of electricity per year
One of the three site canopies
281 Summer Street
Boston, MA 02210
Tel 617.426.5004
Fax 617.426.0046
1511 Third Avenue, Suite 300
Seattle, WA 98101
Tel 206.686.0170
Fax 206.686.0171
www.dimellashaffer.com
CLIENT
State of Massachusetts
USER AGENCY
North Shore Community College
ARCHITECT/INTERIOR DESIGN
DiMella Shaffer Associates
MEP ENGINEERS
RDK Engineers
STRUCTURAL ENGINEERS
Lim Consultants
CIVIL ENGINEERS
Nitsch Engineering
GEOTECHNICAL ENGINEERS
GZA GeoEnvironmental
LANDSCAPE ARCHITECTS
Copley Wolff Design Group
PHOTOVOLTAIC DESIGN
Solar Design Associates
ENERGY MODELING
Buro Happold
LIGHTING DESIGNER
Collaborative Lighting
COMMISSIONING AGENT
WSP Flack+Kurtz
EDUCATIONAL PLANNER
DiMella Shaffer Associates
GRAPHICS
DiMella Shaffer Associates
PROJECT MANAGEMENT
DCAM
CONSTRUCTION MANAGEMENT
Walsh Brothers Construction
PHOTOGRAPHY
Robert Benson