Demand Related Ventilation in Laboratories
Peter James and Lisa Hopkinson
September 2009
Professor Peter James is Co-Director, and Lisa Hopkinson, is Research Officer on
the Higher Education Environmental Performance Improvement (HEEPI) project.
This is based at the University of Bradford, and mainly funded from the HEFCE
Leadership, Governance and Management (LGM) initiative. It aims to improve the
environmental performance of universities and colleges through identification and
dissemination of best practice, events and network building activities, and
development of sector capacity. See www.heepi.org.uk for more details, and
contact information.
Disclaimer: This paper has been prepared in good faith as an objective account of
the discussions at, and matters arising from, Labs21 UK events. The points made
by presenters are reported without comment, and should not be construed as being
endorsed or accepted by HEEPI. The paper does not constitute technical guidance,
and is not a substitute for appropriate professional advice on the subject matter
being discussed. The paper also features presentations by, or about, specific
suppliers. These are included as examples and sources of information, and do not
constitute an endorsement of any specific products.
Demand Related Ventilation in Laboratories
Contents
1. Introduction .................................................................................................................................. 3
2. Principles of Demand Related Ventilation ........................................................................... 3
2.1 Fume Cupboards and Demand Related Ventilation ................................................................. 4
2.2 Room Based Demand Related Ventilation .................................................................................. 5
2.3 System Level Demand Related Ventilation ................................................................................. 6
3. Demand Related Ventilation at the University of Cambridge – Paul Hasley, Chris
Lawrence and Phil Mulholland .................................................................................................... 6
4. Demand Based Control for Significant Energy Reduction in Laboratories –
Gordon Sharp ................................................................................................................................... 8
5. Discussion .................................................................................................................................. 11
Appendix 1 – The Labs21 Design Philosophy....................................................................... 12
Appendix 2 - HEEPI Energy Benchmarks for Laboratories ............................................... 14
September 2009
www.goodcampus.org
2
Demand Related Ventilation in Laboratories
1. Introduction
Laboratories have many environmental impacts. One of the most serious is their
consumption of large quantities of energy. This can be 4-5 times greater than offices on a
square metre basis. The most important component of energy demand in many
laboratories is ventilation, and the associated conditioning of air. This can often comprise
30-40% of total energy consumption, mainly in the form of fan power. The plant is also a
major component of capital expenditure.
This paper1 summarises the presentations and discussion both at, and following, a May
2009 workshop on Variable Air Volume and Demand Related Ventilation at the University
of Cambridge. It has also drawn on relevant points made at other recent HEEPI events on
laboratory energy efficiency and environmental performance.2 The events have highlighted
the fact that recent ventilation approaches have been very supply focused, so that air is
supplied and extracted with little relationship to actual requirements. Moving to demand
related ventilation (DRV), in which air flow is varied according to hazard, and other factors,
could therefore create considerable energy benefit, provided that safety is not
compromised.
The Cambridge workshop was organised by the S-Lab programme of HEEPI (Higher
Education Environmental Performance Improvement), a not-for-profit project which
supports UK universities and colleges in becoming more sustainable through
benchmarking, sharing best practice, and other actions. It also involved a collaboration
with the US Labs21 initiative, via HEEPI’s creation of a UK Labs21 programme (see
www.labs21.org.uk). Labs21 began as a collaboration of Federal laboratories to improve
energy efficiency and share best practice between them through better networking and
staff exchanges. It was founded by the US Environmental Protection Agency, with
additional support from the US Department of Energy, and is now managed by the
International Institute for Sustainable Laboratories (IISL).
2. Principles of Demand Related Ventilation
Demand related ventilation (DRV) is an approach which varies ventilation levels in
accordance to occupancy, use and other factors. In some cases, such as night setback on
fume cupboards (see below), the variation is fixed and relatively inflexible. However, in
others ventilation is varied very quickly in responses to changes in state – an approach
described as demand controlled ventilation (DCV).
Demand related ventilation can be applied at a number of levels:



The device (especially fume cupboards)
The room
The system.
The most effective approaches will be those which integrate action at all three levels.
1
The contents of this paper are the responsibility of the authors, but they have benefited greatly from the
advice and review of Geoffrey Bell, Mike Dockery, Gordon Sharp and other Labs21 experts.
2 Details of, and presentations from, the events can be viewed at www.labs21.org.uk.
September 2009
www.goodcampus.org
3
Demand Related Ventilation in Laboratories
2.1 Fume Cupboards and Demand Related Ventilation
Research by a supplier, Phoenix Controls, suggests that most fume cupboards are
typically used for under two hours a day, on average, and in many cases for only an hour a
day or less.3 Hence, there is considerable scope to reduce ventilation levels at other times.
2.1.1 Constant Air Volume (VAV) Fume Cupboards
Traditional laboratory design has been based on a constant air volume (CAV) approach.
This involves the same amount of air always being supplied to the ventilated spaces, and
exhausted from them. Variations in sash opening are generally dealt with by the provision
of a by-pass channel. Air flows through this vary inversely with the amount of sash
opening. Cupboards of this type are conventionally designed with a face velocity (the
speed at which air travels through the open sash area) of 0.5 metres per second (m/s).
If CAV fume cupboards are not provided with a by-pass then the velocity across the sash
opening will increase as the sash is lowered, which can lead to unstable conditions. There
can also be occasions when by-pass fume cupboards have a higher than normal face
velocity even when the sash is closed due to the problem of balancing the by-pass in the
closed position.
The main means of achieving demand related ventilation (DRV) with CAV devices is
through two-state approaches, in which face velocities are reduced to a lower, standby,
level when the device is not on use, such as night-time. Achieving this safely may require
the sashes to be closed. CAV systems that have this capability can also take advantage of
proximity sensing technology (see below).
2.1.2 Variable Air Volume (VAV) Fume Cupboards
Variable Air Volume (VAV) devices vary air flows in response to load. They provide a
specified face velocity setpoint for all sash positions, but adjust volume flow in accordance
with the sash level. Hence, when the sash is low or closed, the movement of air is
reduced. A typical VAV cupboard will have a 4:1 turndown on exhaust, and 7:1 turndown
on supply air, and ideally have a response time of less than one second. However, not all
designs are capable of such a rapid response.
VAV approaches often have higher first costs than CAV, largely because of their complex
control systems. However, this can be more than offset by reductions in the sizes, and
therefore capital cost, of air handling and air conditioning installations. In operation, they
have the benefits of:


3
Lower energy consumption, from reduced exhaust and supply fan requirements
and, in cases where incoming air is conditioned, a reduction in the amount of air
which needs to be conditioned for humidity and/or temperature (see Table 1 for a
comparison with CAV).
Increased safety because there is much less risk of the turbulent air flows and
consequent spillage arising from sudden changes in fume cupboard face velocities
that can arise in conventional CAV systems.
Quoted in a presentation to the Cambridge workshop.
September 2009
www.goodcampus.org
4
Demand Related Ventilation in Laboratories

Finer control, and much more detailed monitoring, of pressurisation in laboratories
so that any problems can be quickly identified and dealt with.
Realising the full benefits of VAV requires sashes to be lowered or closed as much as
possible. This can be achieved by:


Voluntary action by users, and/or
Automatic closure (or semi-closure) based on sensing user proximity to the device.
As discussed below, there are differences of view on the value of each of these methods,
and the safety of the latter.
Table 1 – Carbon, Energy and Cost Impacts of Fume Cupboards4
Type
Electricity
Heat
Annual Cost
Annual
kWh/annum
kWh/annum
CAV
1,019
28,305
£794
5,784
VAV – Poor
510
14,153
£397
2,892
42
1,179
£33
241
CO2
Emissions (kg)
Sash
Management
VAV – Perfect
Sash
Management
Source: University of Cambridge calculations, based on data from Carbon Trust Good
Practice Guide 320 and usage of 1 hour per day.
2.2 Room Based Demand Related Ventilation
Specification of the number of air changes per hour in each room is a key feature of the
design of laboratory heating, ventilation and cooling (HVAC). Multiple air changes are
necessary for a variety of reasons, including:




Maintaining air freshness by replenishing oxygen, and removing carbon dioxide,
odours and other unwanted substances (usually determined by CIBSE guidance on
minimum ventilation rates).
Ensuring that there is sufficient air to ‘feed’ all extracted devices, such as fume
cupboards (if the supply air is insufficient, contained air can leak back into the
room).
Removal of heat created by occupancy, equipment, lighting and solar gain.
In some cases, requirement for negative pressure in room.
4
Hasley, P., 2009. Energy Efficent Operation of Laboratories at University of Cambridge Using Variable Air
Volume (VAV) Ventilation. Presentation at HEEPI event Cutting Energy Use with Variable Air Volume (VAV)
in Labs, Hospitals and Other Heavily Serviced Spaces - New examples and research in the UK and USA, 14
May 2009, University of Cambridge. Available at: www.labs21.org.uk
September 2009
www.goodcampus.org
5
Demand Related Ventilation in Laboratories
As these factors are difficult to calculate in advance, room air changes tend to be
estimated conservatively.
As with fume cupboards, one simple method of demand related ventilation (DRV) is a two
stage approach, with a standby level for periods when space is unoccupied (e.g. night
setback). A more complex approach is that of demand controlled ventilation (DCV), in
which air flows are varied in response to changes in ambient concentrations of monitored
substances. This method is already used to gauge room occupancy in a variety of
environments, based on monitoring levels of carbon dioxide, which is exhaled by humans
at relatively constant rates. Ventilation can then be increased as concentrations rise.
Gordon Sharp’s presentation describes an extension of this approach to laboratories, with
sensing of harmful substances such as volatile organic compounds (VOCs).
2.3 System Level Demand Related Ventilation
DRV savings can be optimised when combined with a modular approach to plant. For
plant which operates most efficiently at full load, installing several small-mid sized units
instead of one large unit can allow them to be switched in and out, in line with demand.
DRV can also enable lower diversity factors. Diversity is defined as “designing and
operating a system at a lesser capacity than the sum of all the included facilities when
running at peak demand.”5 A laboratory fume cupboard ventilation system whose exhaust
capacity is the same as that of all the individual cupboards would have a diversity factor of
100%. In CAV systems diversity factors have to be high (often 100%) as there is little
variation in the air flows from the fume cupboards. However, device and room DCV
approaches create a greater variation in flows, and make it unlikely that all cupboards will
be operating at full capacity simultaneously. A safe level of diversity is determined by a
number of factors, including:





Number and density of fume hoods.
Minimum laboratory/room air change rates.
Heating and cooling loads.
Fume hood usage patterns.
Extent of sash closure.
In practice, diversity factors have been reduced to as little as 50% for central plant without
compromising safety, as has been the case at, for example, a recent Oxford University
laboratory. This translates into lower capital and operating costs from lowered
requirements for cooling, heating, reheating, fan power, ductwork and piping, and space.
3. Demand Related Ventilation at the University of Cambridge – Paul
Hasley, Chris Lawrence and Phil Mulholland
The University of Cambridge has an energy bill of £10.2 million a year, of which 10% is
from the Chemistry Laboratory (which has over 300 fume cupboards). The university has a
good record in energy efficiency and environmental management, being highly
5
DiBerardinis L., Baum J. S., First M., Gatwood G. T., and Seth A., 2001. Guidelines for Laboratory Design:
Health and Safety Considerations. 3rd Edition. Pub: Wiley New York.
September 2009
www.goodcampus.org
6
Demand Related Ventilation in Laboratories
commended by HEEPI Green Gowns 3 times in 4 years and achieving first class honours
in the People & Planet Green League 2007 and 2008. Nonetheless, there is scope for
further energy efficiency measures.
Table 2 – Carbon, Energy and Cost Impacts of Chemical Laboratories6
Electricity
Gas kWh/m2 Annual Cost
Annual
kWh/m2
(£ million)
CO2
Emissions
(tonnes)
Cambridge
371
332
£1.243
7,204
160
160
£0.549
3,189
132
175
£0.485
2,850
264
175
£0.838
4,807
Chemical Laboratory
DECs – Typical
Lab (100 = D/E)
CIBSE Typical
HE Science Lab
HEEPI Typical
Chemical Science Lab
The Chemical Laboratory has a gross internal floor area of 27,603 m2. It was originally
constructed in 1958, and was recently refurbished in order to support increasing academic
activity (through more fume cupboards, and other ways), and to reduce energy
consumption. Table 2 compares its actual energy consumption, costs and carbon
emissions with various benchmarks. (See Appendix 2 for more information on the HEEPI
benchmarks).
Three key principles in the energy aspects of the refurbishment were:



5 year paybacks (a requirement of the Salix Trust funding which financed part of the
work).
No interference with lab operational demands.
No compromises on health and safety.
A VAV solution was adopted for the new fume cupboards, and a key design issue was
how to ensure a high level of sash closure. Four options were identified:




6
Voluntary user actions.
Automatic sash closers.
Fixed setback of fume cupboard face velocity.
Usage based control, linked to presence detection.
Standardised to a 27,603 m2 gross internal floor area. Hasley, P. 2009. See footnote 4.
September 2009
www.goodcampus.org
7
Demand Related Ventilation in Laboratories
Voluntary user actions were seen as important, but unlikely to be sufficient due to
resistance or indifference by many students and researchers, and the need for constant
re-education to take account of student and researcher turnover.
Automatic sash closure devices were also rejected on the grounds of high capital cost,
difficulties in retro-fit installation, ongoing maintenance requirements, and poor user
acceptance.
Fixed setback of face velocity (typically by stepping down from 0.5 m/s to 0.3 m/s during
night time hours) was rejected for the Chemistry Laboratory due to concern that there
could be 24/7 use, and difficulties in applying to all designs of fume cupboard. (However,
night setback has been used in new CAV installations with two-position sash control in the
University’s Physics of Medicine building).
Usage based control (UBC) was the preferred option. These also reduced face velocities
from 0.5 m/s to 0.3 m/s, but only when presence detectors indicated that a zone in front of
the cupboard was unoccupied. Risk assessments concluded that they posed no threat to
safety. The system was straightforward to install (as it was provided by the supplier of the
fume cupboard VAV controls, Phoenix), required no maintenance, and was invisible to
users.
A simple example of UBC in practice is a room with a single fume cupboard with 400
litres/second extract with the sash fully open, and 50 litres/s supply offset. When no
operator is present, even with the sash fully open, the cupboard is in standby mode at 240
litre/s extract and 190 litre/s make-up air. When an operator enters the detection zone, the
cupboard immediately switches to standard mode at 400 litres/s, and the make-up air
increases to 350 litre/s, with a response time of under a second.
UBC also has a considerable impact on diversity. In a standard VAV system, the worst
case scenario of all users leaving their sashes open requires the system to run at 100%
(i.e. no diversity). With UBC, modelling suggests that the worst case is sashes fully open
for only 10-20% of the time on average. This enables the laboratory to be operated safely
with a diversity factor of 65%.
Of course, UBC (or VAV for that matter) does not suit every lab facility. There are many
variables that will impact on system performance from a diversity and energy standpoint,
including number of hoods, density of hoods in labs, minimum air change rates, heating /
cooling loads, and usage patterns. The most appropriate system approach needs to be
evaluated for each facility. In undertaking this evaluation, the University found the results
obtained by Critical Airflow using Phoenix’s LabPro modelling software to be helpful. This
involves building a profile of a facility, then running a series of calculations to forecast
capital costs, life cycle costs and diversity potential for a range of options (CAV, 2-position
CAV, VAV, UBC).
4. Demand Based Control for Significant Energy Reduction in
Laboratories – Gordon Sharp
Gordon is a Board Member of the International Institute for Sustainable Laboratories, a
prominent member of ASHRAE technical committees, former MD of Phoenix Controls, and
September 2009
www.goodcampus.org
8
Demand Related Ventilation in Laboratories
now Chairman of Aircuity, Inc., a recently established company selling DCV applications in
the USA. (Note that Aircuity does not have technical approval to sell in the EU, but hopes
to achieve it by the end of 2010).
Gordon noted that minimum air change rates in the US are still fixed at around 6-12 air
changes per hour (ACH) (or 10-20 for vivariums). However, for the majority of time lab air
is clean and there is no need for dilution. On the other hand, there are times when
increasing the supply of air above conventional rates could be valuable, e.g. in loss of
containment emergencies. The implication is that there is no one ventilation rate that is
right all the time. An appropriate ventilation rate can only be determined by reference to
the quality of air, which is the major criteria for ventilation of laboratories (but, ironically, the
one factor that is not being monitored). In practice, and where dilution is the main driver of
airflow, Gordon believes that ACH can safely be brought down to 2-4 ACH (for labs) or 6-8
ACH (for vivariums) for much of the time.
The point was illustrated using the analogy of overhead sprinklers. These monitor the air
and are only activated if a problem is detected. Gordon suggested that continuously
ventilating laboratories and fume cupboards at high rates ‘just in case’ of contamination,
was the equivalent of continuously sprinkling water in a building just in case of fire.
The alternative approach is to link air changes dynamically to Indoor Environmental
Quality (IEQ) sensing in all significant spaces. This has previously been difficult because
of design approaches requiring multiple sensors in each room, which has involved high
costs, and required overcoming difficulties in calibration and reliability, which often result in
inaccuracy. However, sensor costs are falling, and a new design approach is available.
The Aircuity system involves a multiplexed sampling system that sends samples of
laboratory air to central sensors at regular intervals. This is done by using a patented
networked air sampling architecture to sequentially route air packets to the sensors in the
same way that data networks route data packets. The air samples are carried in cables
that contain carbon nanotube filled plastic conduits. This avoids cross-contamination of
samples during transport. The sensors include ones for VOCs, particles, ammonia,
carbon monoxide and carbon dioxide, which are said to be sufficient for 90% of
laboratories. In this way a network of labs, typically 20, can be served by one sensor suite,
and more expensive sensors can be deployed. The system can be integrated into Building
Management Systems and can include web-based data collection and analysis. Typically
this enables routine air change rates of 2 ACH, with a maximum dilution of 12-16 ACH for
purging in case of any incidents.
The sensors take samples every 15 minutes which has been shown to be sufficient to pick
up any spills or leakages. In 2008 a comprehensive laboratory IEQ Performance
Monitoring Study was carried out at over 18 sites, with over 300 different lab areas. The
collected data represented over 1.5 million lab hours and with 20 million sensor values.
The averaged results for all sites showed that, for VOCs, for example, low ACH can be
used 99.4% of the time, equivalent to a higher flow needed for 1 hour a week (4 events).
In the worst case in one lab the threshold was exceeded for 3% of time. Gordon noted that
no system was perfect, and that comparisons with conventional approaches needed to
take their weaknesses into account. For example, some incidents – e.g. evaporation of
solvents or other hazardous substances from spills, or from containers on warm days;
September 2009
www.goodcampus.org
9
Demand Related Ventilation in Laboratories
poorly operating fume hoods – could occur for hours, whereas they would be picked up
within 15-30 minutes using DCV. The Aircuity approach could also provide more flexible
incident response, e.g. by rapidly increasing air flows to flush out contaminants.
The same principle can be applied to exhaust systems by using sampling in conjunction
with variable exhaust velocity. Typically the exhaust is run at a high velocity to get it away
from the building but air quality in the plume is often quite clean because of the high
dilution rates. By monitoring the contaminant levels in the plume the exhaust levels can be
reduced significantly, resulting in enormous, 50-75%, reductions in fan power. Seven
exhaust systems in a life science building were monitored over 15 months. It was found
that incidents requiring increased air flow occurred ~0.04% time per fan or ~0.3% per
building, i.e. potential for savings 99% of the time.
Gordon cautioned that the approach requires VAV control of supply and room exhaust as
a prerequisite. It is also not applicable for 3 or 4 containment level bio labs, nor for labs
with a high fume cupboard density (> 1 fume cupboard per 10 square metres). However,
many labs/vivariums and in the US are using it, including the US Food and Drug
Administration. Examples included:
Arizona State University - a LEED Platinum R&D lab facility was originally retrofitted with
this multiplexed sampling system in a small portion of this two lab building complex. This
produced annual savings of $55,333 and a less than 11 month payback. Since them the
system has been implemented across both buildings (33,000 total gross sq ft) with
estimated savings of over $1 million.
GreenLab Seattle – a 75,000 sq ft lab, with a 25,000 sq ft vivarium, which considered a
design based on multiplexing versus a fixed ACH system (9 for lab, 15 for vivarium). The
results showed that the total building energy costs could be cut by $250,000 per year and
the gross first cost savings were $1,010,000 (primarily due to plant downsizing).
Texas Children’s Hospital – which retrofitted 2 floors of a life science facility, including 28
lab areas. This produced $61,000 annual energy savings with a 1.6 year payback. The
sampling revealed many spikes in VOC levels in one lab room resulting from 4
recirculating biosafety cabinets. This was found to be due to technicians using spray
bottles of alcohol in prepping samples. Even in this worst case situation the air was ‘clean’
93% of the time and significant energy was saved even for this lab room.
The system is also used in more conventional environments, where it measures carbon
dioxide, particles and VOCs for better air quality and demand control ventilation of outside
air to save energy. For example, the Bank of America Tower, the second tallest building in
New York, and a LEED platinum building, uses this system for IEQ monitoring and DCV.
Gordon provided other examples of buildings which use the sensing system for humidity
monitoring and DCV control.
Questioned on the mechanical stability of the system and risk of puncturing/piercing,
Gordon noted that the system is self-diagnostic and checks itself.
September 2009
www.goodcampus.org
10
Demand Related Ventilation in Laboratories
5. Discussion
Topics discussed at the various events included:
General Health and Safety – There are concerns that DRV approaches are overturning
long standing traditional approaches without a sufficient evidence base of their safety.
Some critics say that the traditional approach has avoided serious safety issues in labs,
and that the ‘precautionary principle’ should apply. It was noted that there have been a few
legal cases regarding exposure incidents in traditional CAV installations, but these have
usually been settled out of court, and hence are not widely known. They believe that a
proper risk assessment undertaken in accordance with the fume cupboard safety standard
BS EN 14175 should guard against any safety problems.
Safety of User Based Controls – Although these are being used at Cambridge and a
number of other locations, some experts have concerns about their safety and value. One
criticism is that situations could be imagined in which containment is required, but the face
velocity does not increase sufficiently quickly to provide it. (However, no safety incidents
have been identified to date). Another criticism is that UBC is a second best alternative –
and could discourage - voluntary sash closure, which is cheaper and safer.
Implementation can be Difficult – VAV systems are more complex, and several universities
have experienced a steep learning curve. However, a growing number of UK universities
have made it work, and will apply it in future laboratory designs.
System Interactions – A holistic analysis is important as the device, room and system
levels interact with each other. One point to watch is that reducing fume cupboard air flows
does not result in inadequate room ventilation.
Calibration – Some commercial carbon dioxide sensors have had problems of “drifting” out
of calibration, with consequent inaccuracies in ventilation rates. It is important to ensure
that sensors are guaranteed against this (e.g. “1 percent per year drift maximum”).
Recalibration will always be needed at some point, typically every 6 months or so.
Room Variations – There can be considerable differences in occupancy, emissions etc.
within large rooms, and it is important that these are considered in DRV designs.
Sash Management – Several examples were given of effective management. In one
laboratory, open sashes are recorded, and users fined after a number of violations. The
University of California LabRATS programme also produces stickers and other guidance
materials for lab users.7
Commissioning – This is always important in labs, but especially those with DCV as
controls and systems must be working effectively to achieve safe operation and energy
benefits. The traditional view of commissioning has been that it is a process of testing
equipment and control devices at the end of construction in order to prove that they are
meeting the design intent. However, the best results are likely to be achieved when
commissioning is considered as a form of quality control, and integrated into earlier stages
of the design process.
7
See James P. and Hopkinson L., 2009. The Sustainable Laboratory - How Lab Managers and Technicians
Can Make an Environmental Difference. September 2009. Available at: www.goodcampus.org
September 2009
www.goodcampus.org
11
Demand Related Ventilation in Laboratories
Appendix 1 – The Labs21 Design Philosophy
The US Labs21 initiative has demonstrated that a new approach to design and operation
can result in significant environmental, financial and other benefits. This involves:
A design process which has greater integration of sub-systems, and more effective
implementation and quality control.
Architectural principles which place greater weight on engineering and energy
considerations, and adopt more flexible and modular configurations.
Engineering principles which seek a greater understanding of energy loads, have
more adjustable means of matching supply with demand, and ‘right size’ equipment
to closely match actual needs.
A series of HEEPI events have identified some differences between Britain and the US,
but highlighted five key technical areas where the Labs21 approach is relevant to, and
challenges, current practice in the UK:
Low energy ventilation design, aimed at reducing the volume and velocity of air
movements (and consequent fan energy consumption), by methods such as low
pressure drop air handling systems and the use of variable air volume (VAV) fume
cupboards.
Rethinking fume cupboard ventilation systems, positioning, and operating
parameters in order to reduce their volume flow rates, and to optimise the flexibility
of laboratory space.
Evidence-based design, which uses modelling, real rather than ‘nameplate’ data on
equipment energy use, and other techniques, to reduce uncertainty so that overly
conservative rules of thumb and safety margins can be avoided.
More modular solutions (such as plug-in modular fume cupboards with integrated
ductwork) to provide greater flexibility and greatly reduce the cost, time
requirements, and disruption of refurbishments.
More attention to the design and commissioning of controls, which must work well if
design specifications – for both energy efficiency and safety – are to be achieved,
but often don’t.
Labs21 US has also demonstrated that these technical changes cannot be achieved
without a well managed design process that has:
More integrated and engineering-led design, to overcome current problems of
fragmented decisions by specialists, and a lack of understanding amongst some
professionals that heating, ventilation and air conditioning (HVAC) decisions are
crucial to laboratory energy and safety performance, and need to be prominent from
the earliest stages.
September 2009
www.goodcampus.org
12
Demand Related Ventilation in Laboratories
Clear sustainability goals, such as target air change rates or energy consumption
per m2.
Greater involvement by a range of users and facilities staff in order to improve
communication within the project team, and to ensure that designs are practical and
effective.
More integrated and effective commissioning and evaluation so that independent
quality control of this aspect exists from the start of the design process.
Value engineering to minimise whole-life, rather than first, costs and ensure that
removing one element does not – because of the interconnectedness of laboratory
systems - have unexpected and costly knock-on effects elsewhere.
A HEEPI report explores these issues in greater detail.8
8
Peter James, Mike Dockery and Lisa Hopkinson, Sustainable Laboratories for Universities and Colleges Lessons from America and the Pharmaceutical Sector, University of Bradford: HEEPI, January 2007.
Available at: www.goodcampus.org.
September 2009
www.goodcampus.org
13
Demand Related Ventilation in Laboratories
Appendix 2 - HEEPI Energy Benchmarks for Laboratories9
HEEPI’s laboratory benchmarking programme has found that recent HE laboratories
usually have higher consumption per square metre than those built a few years ago. 10 This
trend is associated with, for instance, a movement to work being carried out only in
contained conditions, such as within fume cupboards, rather than on the open bench.
There are also increasing levels of automation in lab equipment (i.e., plug loading), and
more complex information systems (most notably at the work bench), all of this running 247 for a variety of reasons. For these and other reasons, it is very common for laboratories
to have much higher consumption than their design specification – sometimes two or three
times higher.
HEEPI has developed benchmarks for different types of laboratories according to energy
performance, based on “typical”, “good” and “best” practice that existed in 2003/04, and
updated in 2007.11 (Note that even “best” practice within the sector may not reflect leading
edge energy efficiency design, or even what is standard practice within the commercial
sector). Despite the high energy and water consumption and costs associated with
laboratories, there are still very few exemplary sustainable laboratory buildings being
developed by universities and colleges in the UK.
For a hypothetical 7,000 m2 laboratory building, the typical, good and best energy
performance within the sector translates into the following annual energy costs (see Table
1).
Table 1: Annual energy costs associated with a hypothetical 7,000 m2 laboratory
building with typical, good and best energy performance for the higher education
sector12
Type of Laboratory
Best
Good
Typical
Medical/biosciences
£114,000
£221,000
£326,000
Physical/engineering
£68,000
£91,000
£192,000
Chemistry
£292,000
£313,000
£365,000
As the table shows, the difference in annual energy costs between the “best” and a
“typical” laboratory is around £212,000 for a medical/biosciences lab, £124,000 for a
physical/engineering lab and £73,000 for a chemistry lab. Over a 7 year ‘lifetime’ – the
normal one planned for in higher education - the difference between the total energy bills
of the best and typical laboratories would be £0.5 - 1 million.
9
Based on 2001-02 data obtained from previous HEEPI benchmark workshops. See Results of the HEEPI
HE Building Energy Benchmarking Initiative 2003-04, August 2006 www.heepi.org.uk
10 Hopkinson L. and James P., 2007. Sustainable Laboratories for Universities and Colleges - reducing
Energy and Environmental Impacts. Report based on a HEEPI benchmarking workshop held on 26 April
2007. Available at: www.goodcampus.org
11 Ibid.
12 Based on July-December 2008 average UK gas and electricity prices of 3.44p/kWh for gas and 10.9p/kWh
for
electricity.
DECC
Quarterly
Energy
Prices,
September
2009.
Available
at
http://www.decc.gov.uk/en/content/cms/statistics/publications/prices/prices.aspx
September 2009
www.goodcampus.org
14