ASHRAE Journal - May 2020 - 69

COLUMN ENGINEER'S NOTEBOOK

sequestration of carbon and nitrogen to
offset building emissions.

Case Study: The Bartlett School
of Architecture, University College
London

TABLE 3 Projected Implications of the CIBSE17 Five Circular Scenarios.
CIBSE
SCENARIO

AIM

PROJECTED IMPLICATIONS

Universal

Deﬁne potential future uses
for the building and design to
ensure ﬂexibility to accommodate
quick, easy, and cost-effective
adaptation

-Design for disassembly
-Reserved space for capacity growth
-Plug-n-play thermal zoning ﬂexibility
-Building management system extendibility
-Modular HVAC design components

The Bartlett School needed to
Joint Venture Align the incentives of everyone in -Product as service paradigm: "purchased cooling and heating"
refurbish an existing building
the value chain toward optimizing
-Design-build-operate-maintain contracts
the performance of systems -Performance-based incentive for design and construction teams
at 22 Gordon Street to hold the
-Measurable accountability
whole school of architecture. The
- Shared responsibility for performance (including if occupant
participation is necessary as in natural ventilation)
school's representatives wanted
Passive
Minimize the need for active
-Natural ventilation
to incorporate as many circular
systems
-"Free" cooling or heating
economy best practices as pos-Thermal storage
-Phase change materials
sible. They collaborated throughRecover
Reduce the consumption of
-Waste heat recovery
out the design process with the
primary resource ﬂows, such as
-Cooling towers: recycled water makeup, non-chemical treatuniversity's facilities personnel
energy, water and waste through
ment, high cycles of concentration
recovery
- Evaporative cooling (depending on energy-water resource
who would maintain and operate
scarcity versus rainwater capture and ﬁltration)
the building for them.
Pre-Loved
Prioritize the use of pre-used, -Transition from designed obsolescence toward design for in-situ
One key decision was about
remanufactured, refurbished, or
replacement and maintenance
new equipment fabricated from -Design for disassembly, recyclability and reuse of viable materiallowable comfort conditioning
recycled materials.
als from manufactured goods
systems (Figure 6). The desire to
-Equipment leasing by manufacturer
-Take-back/buy-back by the manufacturer or other third-party
adopt unmodiﬁed natural ventilarefurbishment vendor
-Used equipment performance guarantees
tion (Table 3, "Passive") failed due
-Material tagging/passports
to high occupancy densities neces-Design for recommissioning and continuous commissioning
sary to achieve the school's misThe implications of these scenarios imply not only changes to design principles but may
also require changes to the business models used in the construction, HVAC manufactursion, but the team was prompted
ing, and service maintenance industries to incentivize collaboration, reduced material use,
to steer away from a fully sealed
preventative maintenance, longevity of reliable high-performance use and new models of
procurement.
building. Discussions about
user control of the windows in
FIGURE 6 Causal map leading to the selection of user control strategy over the
the mixed mode system resulted in separate modes of
building's air conditioning. Originally Figure 22 from Croxford, et al.15 Image courindication or override, depending on the occupancy of
tesy of Arup as author of diagram.
the space (Table 2, "Share" and "Virtualize"), ultimately
Sealed Building
UCL
Natural
Operation
But With "Trafﬁc Light" Controls
Sustainable
Ventilation
requiring occupants to participate in ensuring indoor
Override
Building
Training
Indicator for
thermal performance through their window-manageMix-Mode
Standard
For Users
Studios
User Control
Strategy
Sessions
ment activities (Table 3, "Joint Venture"). To help the occuImprove
Sealed Building Window Interlocks PIR (Not CO2 Sensor)
pants have feedback with high reliability, the university
Building
For Modulating
Strategy: Fully
Performance
In Ofﬁces Only
facilities team relied on their historical experience manVentilation Flow
Mechanical
aging buildings on campus (Table 2, "Maintain/Prolong")
* Decisions are color coded by phase in which they were ﬁnalized in. Nominally being red
= masterplan; pink = brief/pre-concept, blue = concept; yellow = design development;
to reject carbon dioxide sensors in favor of passive infragreen = construction documents; purple = construction; orange = commissioning.
red sensors. (Factual information from Croxford, et al.,15
* Filled boxes represent decisions taken and dotted-line boxes decisions considered but
not adopted.
pp. 26-27; mapping of strategies, cycles and scenarios
17
10
from CIBSE and EMF by author).
A deeper look at the decision map (Figure 7) reveals
"Share," Table 3, "Joint Venture"). After adopting a mixed
that there were several circular economy solutions intemode approach (Table 3, "Passive") and rejecting decengrated into the design. It started with an early decision
tralized equipment (Table 2, "Substitute Material"), cenby the university to retain the concrete frame (Table 3,
tralized air handling and mechanical cooling (Table 2,
"Pre-Loved") and the district heating connection (Table 2,
"Maintain/Prolong") were deemed appropriate to support
M AY 2020

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