Download II DEVELOPMENTS IN BUILDING ENERGY MANAGEMENT AND

Conference
Paper
II
I986
620.9
DEVELOPMENTS IN BUILDING
ENERGY MANAGEMENT
AND LOW ENERGY
LIGHTING SYSTEMS
Frank Pool
Presented at the Institution of
Professional Engineers New Zealand
Annual Conference, 11 15 February 1985,
Wellington.
-
BUILDING RESEARCH ASSOCIATION OF NEW ZEALAND
[ ! I
THE INSTITUTION OF PROFESSIONAL ENGINEERS NEW ZEALAND,
BUILDING SERVICES GROUP
ANNUAL CONFERENCE, WELLINGTON, FEBRUARY 11-15, 1985
PAPER N0.36:
DEVELOPMENTS IN BUILDING ENERGY MANAGEMENT AND LOW ENERGY
LIGHTING SYSTEMS
AUTHOR :
Frank Pool, BE, ME, Energy Research Fellow
ORGANISATION:
Energy Research Group, School of Architecture,
Victoria University of Wellington, New Zealand
KEY WORDS:
Energy, Cost, Management, Lighting, Low-Energy, Developments
ABSTRACT :
Drawing on information gathered during a recent BRANZ
sponsored study tour of North America and Europe, as well
as the Energy Research Group's work on energy management in
commercial and institutional buildings, this paper describes
recent developments in both building energy management and
low energy lighting systems. Energy management (as distinct
from energy auditing) is a relatively new field and somewhat
different approaches are emerging in North America, the U.K.
and Continental Europe. A similar situation applies to
developments in low energy lighting system design and
operational control.
The best direction to be followed in New Zealand will
involve elements from all these approaches, but modified to
take account of New Zealand's climate, building construction, control and operational practices.
CONTENTS :
1.
2.
3.
4.
5.
6.
7.
BACKGROUND
BUILDING ENERGY MANAGEMENT
2.1 Improved Control
2.2 More Efficient Equipment
LOW ENERGY LIGHTING SYSTEMS
3.1 Reducing Installed Loads
3.2 Improved Lighting Control
LIKELY FUTURE DEVELOPMENTS
4.1 More Efficient Equipment
4.2 Improved Control
SUMMARY
ACKNOWLEDGEMENTS
REFERENCES
1.
BACKGROUND
Since 1977 the Energy Research Group at Victoria University's School of
Architecture has been studying energy use in commercial and institutional
buildings. In contrast to the research efforts in other countries, the
initial work concentrated on studies of actual energy use rather than
detailed computer simulations of predicted energy use. These initial
studies showed that approximately half of the energy use (and hence energy
costs) of buildings did not seem to be closely related to the building's
size, the activities it housed, and other easily measurable building
In subsequent work (2,3) it became apparent that much of
features (1).
this 'unexplained' portion was due to what is becoming termed "energy
management".
The energy use (and cost) of a building is strongly affected by the way the
energy consuming equipment is controlled (or managed). For example, the
heating cost is at least as dependent on the control of the heating system,
the choice of fuel used, and the control of the ventilation system as it is
on the heat loss through the building structure (4).
Energy management is becoming increasingly important throughout the world
as people begin to control energy use and costs rather than just paying the
bills without question (5). With the increasing realization that underpricing energy leads to its inefficient use, the financial incentive to
manage building energy costs is here to stay (6). Coinciding with the
growing interest in managing building energy costs, there have been a
number of recent developments which have led to more efficient equipment
and more effective controls, with clear indications that further improvements can be expected.
Building energy management has already had a widespread impact on energy
use patterns in New Zealand; for example, a recent study (5) showed that
the heating energy use per m2 floor area in the 1100 buildings of the
Wellington Central Business District (CBD) has been reduced. With the
widespread change from oil to gas, heating costs have been reduced overall
in the CBD from $4.8 Million to $3.2 Million (using 1982 energy prices) a
cost avoidance of $1.6 Million between 1977 and 1982 in spite of a 10%
overall increase in floor area. However, before this is taken as evidence
that energy management is being widely practiced, it should be pointed out
that electricity consumption (and hence costs) is increasing in existing
buildings and balancing any savings in heating energy costs (on average).
Other studies (2,3) confirm that successful energy management has been
largely confined to heating systems. However, once heating systems are
well-managed then attention needs to shift towards managing electricity
To put building energy management concerns in
costs (see Figure 1).
-1
perspective it should be pointed out that the average energy cost (insluding tenant electricity costs) for the Wellington CBg
- is ?round Sl1.m- .yr
compared to an office rental cost20f ${25 - S185.m .yr- and an office
worker wage cost of over $1000.m .yr- (5). This clearly illustrates that
good building energy management can not justifiably involve making building
occupants noticeably uncomfortable. However, if you take account of the
occupants needs or involve them more in the control of their energy
consuming systems, you can save money on energy costs whilst maintaining or
improving their satisfaction with their environmental conditions. Occupant
perceptions of comfort involve more than just temperature, humidity and
lightinglevels provided; it also strongly involves the perceived quality
of conditions, and effective occupant control of equipment is a very
important part of this.
Following on from the work on building energy management at the Energy
Research Group, the author was fortunate enough to receive a Study Award
from the Building Research Association of New Zealand (BRANZ). This award
enabled the author to study overseas at first hand developments in both
building energy management and low energy lighting systems. A more
detailed report of the findings of the study tour is available (7). As
these fields are in a considerable state of flux, the study award enabled a
good impression to be gained of the most significant developments occurring
overseas which form the basis of this paper.
BUILDING ENERGY MANAGEMENT
Building energy management has become synonymous with heating systems (and
to a lesser degree cooling systems). This strong popular association
between I energy' and 'heating' in commecial buildings is pervasive amongst
building services personnel and consulting engineers worldwide. This
concentration on heating energy costs is not always justified (see Figure
1).
It is important to distinguish between energy consumption and energy
cost. Although one litre of diesel has a calorific value of 38 MJ it is
nowhere near as useful in a building as 38 MJ (10.56 kwh) of electricity,
nor are the costs the same. At the end of the day, energy costs are what
matter, and it is up to the marketplace and local and central government to
determine the appropriate price for each form of energy.
One of the first steps of any building energy management programme is to
use the cheapest possible fuels and ensure that whatever fuels you do use,
you are paying the lowest possible price for them. For example,
electricity is usually available at several different tariffs and it is
worth checking if electrical loads can be charged at a cheaper tariff. The
next points to check are the penalty charges for maximum demand, time of
day, power factor etc., where large cost savings can often be achieved.
Only once the cheapest possible fuel at the lowest possible price and
penalty costs is being used, should reducing the energy consumption be
investigated.
A major problem with building energy management can be that it only deals
with the energy flows paid for directly by the building owner, and where
energy costs are passed on in the rent there can be little incentive to
manage energy costs. A similar situation can exist where tenants do not
pay directly for their energy use; if tenant energy costs are paid on a
floor area basis, no one has much of an incentive to manage energy use (6).
To a considerable degreein NZ, building energy management has been
concerned with reducing central HVAC and/or process energy costs. In
recognition of this fact, energy management of lighting systems is
discussed separately in Section 3 as such systems tend to be of greater
interest to the building tenants.
Figure 1
ENERGY COSTS THROUGHOUT THE YEAR IN A
WELL-MANAGED GAS-FIRED OFFICE BUILDING
GAS FOR HEATING
Y
W
W
I
COOLING
I
RENTABLE AREA I S 16200 50 M
NUMBER OF OCCUPANTS I S 735
ANNUAL ENERGY COST WAS $178.858
ANNUAL ENERGY USE WAS 8500 GJ
GIVING $10.92/50 M/YR
.
GAS FOR HEATING
- 8.38
/-811.227
Figure 2
THE EFFECT OF ENERGY-MANAGEMENT IN AN
OIL-FIRED WELLINGTON OFFICE BUILDING.
(Energy Management Started in 1978)
NB ALL DATA BELOW
REFERS TO 1982
FOR HEATING
-OIL
$ 1 2 008
33.81
-
-COOLING
$2288
- (OBI
8.48
-TENANT
ELECT. 1041
$15.042
42.S
-
-LIFT$
PWP$ FWS 108'
$4.737
13.48
-
-PUBLIC
LI6HTING 104)
$1.358
3.88
-
Once the cheapest fuel is being used, reducing central HVAC energy costs
becomes a matter of either reducing the hours of use of plant or reducing
the load on the plant (better control) or increasing the efficiency of the
plant (more efficient equipment). These two areas shall now be considered
separately.
2.1
Improved Control
The cornerstone of many (if not most) successful building energy management
programmes is controlling the HVAC equipment to both reduce the run-hours
and reduce the average load of the more 'important' (in energy cost terms)
plant items. The means of improving control range from ensuring that any
existing controls actually work properly (often a major cause of energy
waste in existing buildings) to installing and using effectively a
computerised Energy Management and Control System (EMCS).
Figure 2 illustrates the major savings that were achieved through improved
control of the HVAC system in an oil-fired Wellington office building. It
can be seen that the mid-winter peak heating load has changed very little
with the main savings being achieved initially in the summer months by a
reduced use of both heating and cooling. With the Hot Water Service (HWS)
system changed to operate directly by electricity instead of indirectly via
the oil-fired boilers, the latter could be turned off completely on warm
days in mid-summer. The control problem then moved to reducing the use of
the boiler on those spring and autumn days where the building was
effectively self-heating although the original control strategies used
would have required the boiler to be running all day anyway. This building
is now controlled by a computerised EMCS bureau service which successfully
operates approximately twenty buildings on a commercial basis (including
the building illustrated in Figure 1).
There is nothing magical about computerised EMCS, they simply provide a
convenient method to use the power of a computer to apply energy efficient
control strategies in a building. The energy savings shown in Figure 2
could have been achieved by a more conventional control system, but it was
just more convenient to use a computerised system.
Background to Computerised Energy Management and Control Systems
(EMCS)
Since the 1960's computers have been used to control very large commercial
buildings and complexes, especially Universities, Hospitals and Military
Bases. Some of these systems had up to 15,000 points (sensors and
controllers) but were rather expensive due to their requirement for hardwired communication channels to each point, and even where several points
were connected on the one line, the multiplexing devices or intelligent
outstations tended also to be rather costly. Although these systems were
very expensive (several hundred thousand dollars and upwards) several
manufacturers successfully sold them in their thousands, and indeed
versions of these systems are still being successfully marketed.
a)
.
Although such systems, by their very expense, were really only suitable for
quite large buildings, some enterprising companies have successfully used a
central computerised EMCS to control a number of quite independent buildings as a bureau service (often over dedicated phone lines); that is they
will run a building for the owner, and hopefully the energy cost avoidance
(savings) will cover the fee with a profit (energy savings) left over for
the owner too.
Because of the high cost of these systems, many of them offered services
other than just the management of energy, they frequently looked after
security (especially with card-access sytems), and occasionally monitored
fire alarms as well. Such systems also had benefits in increasing the
effectiveness of engineering and management staff, enabled better planned
maintenance of equipment, and sometimes allowed plant maintenance personnel
and caretakers to be centralised.
Indeed, it is likely that variants of these large dedicated EMCS will have
a continuing place in large buildings and complexes, although there will
continue to be a cross-fertilization from developments in microprocessor
based systems. This will enable standard off-the-shelf software controlled
devices to replace hardware controlled devices and will improve reliability
and flexibility and hence reduce costs (relative to inflation anyway).
Development of Micro-Computer Based Systems
b)
Since the first oil shock in 1973, a new approach to computerised building
energy management has been apparent. This approach has made use of the
explosive development of micro-computer based technology the computer on
a chip.
-
In contrast to the older large centrallised systems, these systems do not
always use a central computer to take information from passive sensors with
the computer or its operator then deciding what to do and sending control
signals to various controllers to start plant and equipment. The microcomputer based systems make use of a configuration where the computing
power is usually much more widely distributed, so that a local controller
might take a signal from a sensor and then decide (be programmed) to open
the fresh air damper (say) without having to ask the central computer
(processor) what to do. The spread of such distributed intelligence
systepls, allied with much less expensive multi-plexers, the development of
dial-up-modems and individually addressable points, has greatly reduced the
complexity and cost of data communications. New possibilities have opened
up with, for example, networked systems comunicating via autodial modems
(they ring each other up themselves) over standard telephone lines, and
local controllers having self-learning capabilities. Systems based on
these ideas are already available and undoubtedly will be developed further
(7).
All these factors have combined to reduce the cost of such systems to
thousands of dollars (from hundreds of thousands of dollars) and they are
now being sold in their thousands. The cost has reduced to a level where
such systems are now appropriate for smaller commercial buildings, and with
the systems designed to be expandable, only a small initial investment is
required, thus allowing for the possibility of future system expansions to
be paid for from the energy savings achieved.
This is an extremely fast developing field and considerable care is needed
to chose the most appropriate systems. Guidance however is available on
the technical side of writing specifications, evaluating tenders for these
systems, installing them, etc. (8). For an overview of the current
state-of-the-art in computerised EMCS's, readers are referred to an
excellent recent book by Gardner (9), no doubt others are (or soon will be)
available.
2.2
More Efficient Equipment
In an existing commercial building, the energy consuming systems will tend
to reflect the level of energy efficiency prevailing when the building was
built. In many cases there have been large advances in the efficiency of
energy consuming'equipment since the building was built, so much so that it
may be profitable to replace perfectly good equipment with more efficient
new systems. To a large degree, these issues are very dependent on the
level of technology available, the price of the equipment, the cost and
availability of various fuels, and an organisation's investment criteria
(cost of borrowing money, etc.).
..
It is almost uniformly assumed that energy management in commercial
buildings is predominantly (or solely) concerned with heating systems, be
they space heating, hot water service (HWS) or process heat. Certainly
there are many buildings where heating costs dominate the energy cost
picture, and frequently these heating costs can be drastically reduced.
Figure 2 illustrates some of the points to be looked for in heating system
energy management, including:
- reducing the amount of reheating,
- shutting the boiler down in summer by changing to a separate HWS
system,
I
improving the boiler management (in this case by an EMCS) and
rebalancing and recommissioning the heating and ventilation systems.
-
Now although impressive savings have been achieved in the building
illustrated in Figure 2 the heating cost could still be further halved by
converting to natural gas (instead of oil) firing. Buildings using a
relatively cheap fuel such as natural gas can have a heating energy cost
which is quite small compared to the other overall building energy costs
(see Figure I ) . In Figure 2 the existing boiler would be quite efficient
when running at full load to preheat the building in mid-winter, but this
period of high efficiency operation would be overshadowed by the majority
of the boiler's operation at only part-load. At part-load a boiler's
efficiency reduces very rapidly indeed, hence most of the boiler's
operation occurs at well below its peak efficiency.
.
A solution to low average boiler efficiency caused by predominantly
part-load operation would be the replacement by modular boilers. The logic
behind modular boilers is very simple; replacing a large boiler with
several identical smaller boilers (modules) which individually spend more
time operated at full load gives a much higher overall boiler system
efficiency. There are other benefits as well, if one module has operating
problems then its maintenance can be deferred until convenient as the other
modules will probably have enough capacity to meet the heating load. This
gives a higher overall system availability (proportion of the time the
heating system is available) and makes boiler maintenance more relaxed and
hence less costly. Modular boilers are usually gas (or oil) fired but coal
fired modular boilers are not far away. Of course replacing the existing
boilers is a costly, often disruptive, task and needs to be balanced
against the anticipated savings.
Actual Hot Water Service (HWS) energy use in a commercial building is
usually quite minor ( l o ) , although to judge from some new buildings fitted
with expensive solar HWS systems, this is still not widely recognised.
Many existing commercial buildings have the HWS supplied from the main
boiler, but this has the unfortunate result that the main boiler has to run
(or be cycled on and off) wherever the building is occupied. In this
situation urgent consideration should be given to running the HWS system
separately; with the boiler or heater (often electric) located as close as
possible to the actual point of HWS end-use this will minimise the considerable standing losses of most HIS systems.
Of course the central energy use of a building usually involves much more
than just a heating system. Fans, pumps and lifts can have appreciable
energy costs (see Figures 1 and 2) and it can be worthwhile to examine the
potential for reducing energy costs, especially if these systems are
undergoing major maintenance/refurbishing anyway. Reheat, constant-volume,
and inadequately zoned HVAC systems can all offer a considerable conservation potential if more efficient equipment and improved controls are used.
3.
Low Energy Lighting Systems
In a commercial building with a well-managed heating system using a
relatively inexpensive heating fuel, lighting can become the major energy
cost (see Figure 1). Initially, lighting energy management can appear
rather daunting as many tenants are often involved, and a large number of
light fittings and switches must be modified. Even determining the
lighting energy cost itself can initially seem to be difficult as it is
usually metered with other general equipment loads, but in practice this is
not an insurmountable problem (11).
Reductions in lighting energy use can be achieved in two main ways, by
reducing the overall lighting installed load (watts/m2) and by reducing
wastage by only using the lights when they are absolutely needed. We will
now briefly examine these two areas:
3.1
Reducing Installed Loads
There are many different types of artificial lights available, with each
main type sharing certain general advantages and disadvantages. At the
outset of any lighting energy conservation programme it is worth checking
if you are using the most appropriate type of lighting for your needs in
each different situation, bearing in mind that there have been major
developments in lighting technology in recent years. For example, 70W and
150W High Intensity Discharge (HID) lamps with quite good colour rendering
are now available from Thorn-EM1 in NZ, enabling HID lamps to replace
fluorescent tubes in indirect lighting applications, giving greatly reduced
energy use and-a longer lamp lifetime.
Once you have checked that you are using the most efficient type of
artificial lighting for your application, the next step is to check that
you are using the most efficient available light source and control gear
for the light output required. For example, Philips have recently released
a 32W tube and 4W ballast (12) which replaces the standard 40W fluorescent
tube with a 10W iron-core quick-start ballast, 50W reduced to 36W - a 28%
direct lighting energy cost reduction for approximately the same light
output, better colour rendering and longer lamp lifetime and far easier to
control too.
It may also be possible to reduce the overall light levels or provide a
mixture of high and low lighting levels instead of a uniform high lighting
level. There have also been major advances in lighting fixture's optics;
with less light being wasted or lost in the fixture itself, a better spread
of light being possible, etc.
The recent advances in lighting technology mean that it is possible to
greatly reduce installed lighting loads. For example, to provide a uniform
500 lux on a horizontal working surface with fluroescent lighting used to
require 20-25w/m2 (total), this can now be achieved with 10-15w/m2 (with
similar lighting quality) by using modern lighting technology (7).
3.2
Improved Lighting Control
Lighting control is a rapidly developing field with major implications for
reducing lighting energy costs.
Since the first oil shock of 1973, designers have rediscovered daylighting
which is now increasingly being incorporated into the design of new
buildings. Some degree of daylighting is already available in most
existing buildings. Photocell controls, separate clearly marked perimeter
light switches, automatic/off systems with reset controls, and dimming with
solid-state ballasts all offer a considerable potential forany daylight to
replace some of the artificial lighting use.
The other major area of improved lighting control is related to occupancy.
Large lighting energy cost savings can be made by lighting areas only when
they are occupied. There are a variety of methods to achieve this (most of
which have been used already in NZ) including:
- sound sensors which turn off the lights when no sound has been
detected for a certain time.
- Automatic-off systems which automatically turn the lights off at
certain times (eg lunchtime); if the occupants still want the
artificial lights then a reset switch or device must be used.
- Ordinary light switches closely related to the office layout and task
lighting requirements.
-.
The building in Figure 1, a fairly typical large Wellington office building
illustrates the energy cost savings potential in lighting. Figure 3 shows
the layout of lighting circuits, and the location of the lighting controls
for a typical floor in the building. Some of the perimeter lights are on
separate circuits, yet all fourteen lighting switches are grouped around
the services core with no indication of which lights they operate: they are
used as a single switch would be used.
Figure 3
FLOOR 11
LIGHTING CONTROL AND CIRCUIT LAYOUT
(see also Figure 1)
KEY:
7
Number of C i r c u i t
8
Switch
Approximately two out of the 12.5 hours of lighting use per day were for
outside normal working hours lighting, mostly for the nightly cleaning.
This means that there is clearly an opportunity to reduce the lighting
hours of use by around 10% if the cleaners and after hours lighting could
be confined to only those areas where work is being done, rather than
lighting the whole floor as occurs at present.
Although the building has quite a deep floor plan, approximately 35% of
the lights are next to exterior windows. These lights could be turned off
for some of the working day if the lighting control system was organised to
take advantage of daylight availability near the perimeter. In Wellington,
daylighting could replace up to 90% of the perimeter lighting, given
appropriate controls, reducing the overall tenant lighting energy use by
around 30%.
Figure 1 shows that the tenant electricity cost contributed 76% of the
whole building energy cost of $177,000. Given the lighting energy use
fraction of 85%, if improvements were made to the tenant lighting controls
to enable daylighting to be used next to external windows, then up to 17%
of the building's total annual energy costs could be saved (30% x 76% x
85%) or $30,000 pa - all without changing or replacing any lights. Further
savings would also be possible through reduced cleaner and after hours use
of lighting. Now, such a large reduction in total building annual energy
costs looks very attractive at first sight, but the cost of changing 250
light switches and nearly 2,500 light fittings would not be inconsiderable.
I
The high potential savings due to daylighting by no means exhaust the
possibilities; the reduction in cleaning and after hours lighting use; the
use of task lighting to replace the present uniform lighting, reduced
installed lighting loads due to higher efficiency tubes and lower loss
ballasts; and the installation and use of lighting controls such that
lights can be turned off in unoccupied areas; all offer a combined lighting
energy savings potential even greater than that of daylighting.
If all the potential lighting savings were implemented in a building such
as that illustrated in Figures 1 and 3, the lighting energy use could be
reduced to approximately half its present value. This would represent an
annual savings of $57,000 or 30% of the whole building's energy cost or $78
per occupant, a considerable saving indeed. In fact, such a saving would
represent about 2% of the rental cost in such an air-conditioned building,
a figure that no good manager should ignore.
..
In conclusion then, the prevalent attitude that little can be done to
reduce lighting energy costs is unnecessarily pessimistic. There are many
aspects of lighting that are potentially very rewarding from an energy
management point of view, and with the lighting developments occurring now
these conservation opportunities will increase in the near future.
LIKELY FUTURE DEVELOPMENTS
Predicting likely future developments in new fields such as building energy
management and low energy lighting systems is a rather tricky business.
The lines of development being pursued are quite different in the UK,
Continental Europe, and North America (7). Economic, social and political
developments in various parts of the world will also influence developments
to a considerable degree. Nevertheless, unless there is a major reduction
in world oil prices or a collapse of the world economy, certain trends are
discernable.
These trends will be dealt with for convenience under the headings of
efficient equipment and improved controls and will concentrate on how these
developments will affect the situation in NZ.
4.1 More Efficient Equipment
Since the first oil crisis of 1973, enormous efforts throughout the world
have been put into developing more energy efficient equipment for
buildings. Some of these developments have been widely accepted (e.g. VAV
systems), some are beginning to be accepted (e.g. modular boilers), and
some are still moving from the laboratory to the demonstration and
commercialisation phase (e.g. solar powered chillers). There are also, of
course, many potentially important developments at the research or
laboratory stage (e.g. low-cost photo-voltaic electrical generation
modules), but only time will tell which will be cost-effective.
a)
HVAC Systems
In new buildings (which also must be managed) there have been major changes
in the types of HVAC systems commonly used, with much more efficient
systems now being installed. However, kt would appear that the building
professions still to some extent ignore energy considerations to judge from
some of the highly glazed buildings with no shading still being erected.
Still, NZ is by no means alone in this regard.
In NZ a major problem arises from the non-availability of natural gas in
the South Island which leaves many buildings still using oil for heating
with no cheap replacement fuel, although coal may be an option for the
larger buildings.
The gradual adoption of passive solar design principles, improvements in
controls and management (see the following section), and the slow but
steady growth in the use office equipment, will probably mean that heating
energy costs decline slowly on average. The increasing availability of
more efficient heating systems such as modular boilers will also help. The
advent of smaller automatic modular boilers will enable the heat sources
(the boilers) to be located much closer to the point of energy end-use,
reducing pipe losses and standing losses as well as increasing the system
load factor which in turn will increase the average boiler efficiency.
Intermittent loads, such as Hot Water Service (HWS) in office buildings,
will increasingly be served by heat sources located near the point of
end-use. This is really just a logical extension of the principle behind
thc hot-air hand drying units which are becoming so popular - supply the
service required (hand drying) directly at the point of end-use rather than
indirectly via a towel and laundry system. Similarly,one should supply the
hot (or warm preferably) water where it is actually needed rather than
indirectly via a boiler, calorifier, and long pipework.
The principles involved in point-of-end-use HWS systems also apply in many
other HVAC applications where a small (sometimes less efficient and using a
more expensive fuel) unit serving a load directly can give a lower overall
energy cost system than supplying the load from a distant central plant. A
good example of this principle is in the air-conditioning (mostly cooling)
of computers, where a less efficient unit air-conditioner is likely to have
lower energy costs than using the central building air-conditioning which
then will spend a far greater time operating at very low load and hence low
overall efficiency.
Steady improvements in the energy efficiency of all items of HVAC plant can
be anticipated. Both in the U.K. and North America it was felt that the
Japanese would be far more involved in the production of HVAC equipment
worldwide. It was felt that there were strong parallels with the early
1970's and the subsequent explosive growth of the Japanese automotive
industry, where they initially produced conventional products with very
good quality control and reliability at extremely competitive prices, and
their competitors were too slow to respond and hence lost large sections of
their markets to the Japanese (7). Air-to-air heat exchangers are a
developing area that comes to mind where non-traditional suppliers could
make large inroads.
b)
Lighting
Moving now to lighting, recent advances in higher efficiency light sources,
lower loss ballasts and control gear, and more efficient luminaires enables
lighting energy use to be considerably\reduced without reducing lighting
levels or compromising the quality of lighting (see Section 3.1).
Developments in the technology of daylighting and a worldwide re-assessment
of the need for high uniform lighting levels further increases the
potential lighting energy savings.
Developments in more efficient lighting can be expected to continue for
some time yet, it is not even possible to speculate where this will end,
especially as the current efficiency of many of the components of lighting
systems are considerably below their theoretical maximum levels. For
example, new fluorescent tubes rated at 104 lumens/watt compared with the
current 90 lumens/watt are now available from Philips (12). Now, although
this development is very impressive, the theoretical maximum for
fluorescent lighting technology is approximately 350 lumens/watt, so major
breakthroughs in lamp efficacy to say 200 lumens/watt cannot be discounted.
A minor revolution is also occurring with ballasts. High frequency (HF)
electronic ballasts and very low-loss conventional ballasts are now
available which use less than 10% of the lighting system power (12),
compared with 20% for conventional iron-core ballasts. It is likely that
even lower loss ballasts at around 5% of total circuit power will soon be
available. Although HF electronic ballasts are more expensive than
conventional ballasts, this differential can be expected to drop steadily
with both continuing research and development and economies of scale.
Electronic HF ballasts are now claimed to be economic on energy savings
grounds alone in Europe for new installations, and they offer other major
advantages in new and retrofit applications that make them worth
considering in NZ even now. These advantages include:
- No noticeable flicker
- Dimmable control becomes easy and efficient (see Sections 3.2 and
4.2)
- Reduced cooling loads
- Reduced lamp and ballast maintenance costs
- Fast flicker-free starting
- High power factor of circuit (0.96)
- The possibility to initially dim the whole lighting system and
gradually increase the power as light output slowly drops over the
lamp lifetime and dirt builds up on the fixtures (7, 13) - thereby
giving a constant useful light output and greatly reduced electricity
costs over the lamp lifetime (offering at least a 10% energy and lamp
lifetime savings).
High intensity discharge lights inherently have a much higher efficacy than
fluorescent light sources, and they are gradually becoming more suitable
for general building lighting applications. Uplighting using relatively
small High Intensity Discharge (HID) lamps now offers an alternative to
ceiling mounted fluorescent tubes at a similar or lower energy cost (14)
and have recently become popular in the U.K. and have appeared in NZ too.
Research is underway on electrodeless HID lamps which would be both very
efficient and dimmable and could have a major impact if they proved to be
feasible and economic.
There have recently been major advances in the state-of-the-art of
luminaire design with improved optics and integral air handling facilities.
The advances in optics allows a much greater percentage of the light from
the light source to be usefully utilised leading to further reductions in
lighting installed loads. Air handling facilities (supply and extract)
built into luminaires can offer considerable advantages for HVAC design as
well as removing much of the heat of the lights before it becomes a cooling
load and improving the light source efficiency by maintaining it nearer to
its optimum temperature.
Finally, the trend towards mixed general and local lighting in buildings
allows major energy savings to be made by both reducing installed lighting
loads and enabling improved daylight and occupancy related control as well
(see Section 4 . 2 ) . This reduction in lighting energy costs can be combined
with improved visual appearance of spaces and reduced glare, in other words
an improvement in the quality of the lighting.
Combining the effects of all the disparate trends in lighting it is clear
that lighting energy loads will continue to reduce whilst the quality of
lighting is improved, and there is a distinct possibility of major
technical breakthroughs in light sources as well.
Improved Control
Prnhably the most spectacular advances in building energy management and
low energy lighting have been made in the area of improved control. Of
course, controls have always been a major determinant of building and
tenant energy costs, but it is only comparatively recently that this
has been widely recognised as important. There is little doubt that
designers are still discovering the importance of controls and we can look
forward to a time in the near future when control systems are recognised as
of equal importance to the installed equipment loads in a building.
Plotting developments is rather tricky as the field is in quite a state of
flux with many simultaneous trends occurring, often with a strong regional
or national bias involved.
4.2
Underpinning many of the developments in controls is the explosive
development in computer technology which shows no sign of slowing down in
the near future. It is sobering to reflect that the now ubiquitous
hand-held scientific calculator has been with us for less than fifteen
years. What will the next fifteen years bring? Will developments just
entering the marketplace now be as revolutionary as some of the
developments that have occurred in the last decade?
There is little doubt that advances in electronics, computer technology and
communication systems will enable more effective and energy efficient
operation of systems. The question is, what will this enhanced control be
used for? Will it be used to enable more effective central control of
building services, or will it be used to allow the building occupants to
have more effective personal control, or some combination of both? This
dichotomy in how advances in controls will be used has a strong regional
bias; with North America tending towards centralised automatic controls
and uniform environmental conditions, the U.K. moving more towards a
decentralised combination of automatic and occupant controls, and
Continental Europe falling somewhere in between these two extremes (7, 15).
The direction we will follow in NZ will almost certainly fall between the
two extremes with a strong move towards mixed automatic and occupant
control, but with somewhat less emphasis on very high (and energy expensive)
levels of en~ironmenta1'~uality'
than seems to be prevalent on the
Continent. Of course, there are many exceptions to these generalisations,
but they still remain extremely useful in explaining, for example, the
almost total lack of interest in North America in pull-cord lighting
controls.
a) Building Energy Management
The management of building HVAC services (lighting is considered in the
next section) is undergoing considerable change at present, and it can be
expected that this will continue for some time yet. It seems clear that
there will be major developments in both individual controls and in control
systems. There are .also some tentative moves towards combining the
currently separate control systems for energy management, fire, security
and maybe even office communications into a Building Management System
(BMS )
.
Individual controls, sensors, and actuators are becoming available in
innovative new configurations, offering greater accuracy and reliability,
costing less, and able to be controlled by Direct Digital Control (DDC)
rather than via pneumaticldigital or analogueldigital interfaces. A recent
International Symposium (16) identified a lack of control accuracy and
reliability, and sensor calibration drift as some of the major impediments
to improving the performance of HVAC systems. These problems also severely
limit the performance advantages of sophisticated control algorithms over
simpler control strategies. If temperature and humidity sensor readings
are likely to be somewhat in error, then devising a reliable and energy
efficient control strategy for, say, economiser or free cooling cycles, can
be almost impossible. Fortunately, the advent of electronic controls and
increasing competition between control manufacturers means that the days of
'HVAC grade' (i.e. not particularly accurate or reliable) controls are
passing (7). Not before time either!
Moving from individual controls to control systems, NZ is somewhat behind
in the availability and widespread use of computerised Energy Management
and Control Systems (EMCS). This is not entirely a bad thing as it means
only the best overseas developments will be chosen to either manufacture
in NZ or import. The high level of electronics and software expertise in
NZ and the relatively low wage rates mean that there are good business
opportunities in this field for innovative NZ electronics firms. With
approximately 50,000 commercial buildings in NZ (plus an enormous
Australian market) there is certainly a large enough market.
Both in the U.K. and U.S. (and no doubt in many other countries as well)
there has been a rapid growth of small innovative electronics firms
offering a wide variety of EMCS systems. These firms tend to offer
intelligent modules that can be networked together into a flexible,
relatively low-cost system. Thus, it is no longer necessary to lay out an
enormous initial sum for an EMCS, few modules for say $5,000 to $20,000,
can be installed and then system expansion is funded by the subsequent
energy cost savings. This method of implementing an energy management
programme is far less risky than purchasing a $100,000 (plus) comprehensive
EMCS. Therefore the fastest growth in EMCS systems can be expected in
these modular networked systems.
In North America a particularly interesting development is the growth in
third party financing - a scheme whereby a 3rd party (owner = 1st party,
consultant = 2nd party, outside investor = 3rd party) finances the energy
conservation measures in a building (often installing an EMCS in the
process) in exchange for a share of any energy cost savings achieved as
well as any tax credits and accelerated depreciation benefits (7).
This removes the element of risk or investment by the building owner and
thereby overcomes what is undoubtedly the major impediment to building
energy management in New Zealand - the lack of knowledge in energy
management by building management and an extremely strong reluctance to
make financial investment decisions or take risks (conservatism). Based on
the North American experience, there would certainly be demand for 3rd
party financing of building energy management, if it were available. At
the national level everyone benefits as well by needing to spend less on
developing new sources of energy supply (power stations, coal mines, gas
fields, inter-island DC links, etc).
Another potentially significant development lies in the area of building
energy management bureau or management services, the situation where a firm
spccialises in operating buildings in an energy efficient fashion for a
straight management fee. This has already been successfully done in NZ for
some years now. With the advent both of less expensive networked EMCS and
of autodial modems for telephone data and control communications, the
financial attractiveness of bureau or management services will improve.
For building owners/managers who want to avoid personal involvement in
energy efficient building operation but yet still reduce or manage energy
costs, employing bureau or management services may be the appropriate
approach.
Progressive importers/distributors/manufacturers of EMCS and existing
property management firms are obvious candidates for offering energy
management services, as well as dealing with leasing of EMCS equipment or
services. With the present climate of energy prices, there is no longer
any justification for the management of medium to large buildings ignoring
energy management.
b)
Energy Efficient Lighting
The control of lighting systems, after the control of heating systems, must
be the area of energy management where some of the largest energy cost
savings can be made. Major advances are now occurring, and the results of
some rather important lighting research in the UK (16) will alter
considerably the way we regard lighting controls. Lighting controls are
particularly important not only from the energy cost point of view, but
also from the viewpoint of visual performance, perception of interior
spaces, and occupant satisfaction.
In lighting, energy efficient control is being approached,fromtwo opposing
directions, fully automatic control and improved manual control. There is
a strong regional bias in this matter, with the U.K. opting for manual
on/off control, and North America moving strongly towards fully automated
on/off and diming controls (7). The work by Crisp in the U.K. (16) has
shown quite clearly that people are very capable of turning lights on when
internal lighting conditions are inadequate, yet rarely turn off or dim
lights when they are no longer required. Therefore the challenge in
lighting control is not how to turn lights on, as people can do that rather
well with manual switches, but rather in devising methods to dim or turn
off lights when they are no longer required,or more daylight is available.
There is no doubt that improvements in lighting control can lead to large
lighting energy cost savings without appreciably compromising the
occupants' visual 'comfortq,which of course is the main reason for
installing lights and their controls in the first place. In the U.K. there
have been several successful lighting control demonstration projects (17)
where the lighting controls were improved in existing buildings leading to
a simple payback on investment of three years or less, and without causing
any appreciable occupant dissatisfaction. The methods used vary with the
applications, there is no universal solution, but rather a number of
options which are appropriate for different lighting control situations
(15)*
For example, in intermittently occupied spaces such as toilets, access
tunnels, boardrooms and corridors, some form of occupant sensing lighting
controls using movement or noise detection would be one of the preferred
solutions. For perimeter lighting control in an open-plan office building
photocell on/off or dimming controls or a lunchtime automatic-off with
manual reset control system would be some of the better control system
choices.
For the interior spaces in an open-plan office, a minimum level of
illumination (either daylight or artificial lighting) should be provided
during normal working hours with some form of task or occupant controlled
additional lighting.
What will become more common is the use of many different lighting control
schemes which will be tailored to the requirements of the particular spaces
being lit. Different lighting control systems are appropriate for
different lighting control problems, this is a developing field so we can
expect a wide range of new products. Our task will be to critically
examine the products and match them to the actual lighting control
requirements. Good lighting design is a complex subject and care should be
taken that all aspects are considered, of which energy costs is only one
aspect (albeit an important one).
5. SUMMARY
This paper has argued that major energy conservation opportunities are
opening up in building energy management and low energy lighting systems.
These fields are in a considerable state of flux and this will probably
continue for some time yet, thus opening up even more exciting
opportunities to reduce and manage building and tenant energy costs.
Although NZ is lagging behind the rest of the world in these fields, this
will decrease with the reduction of NZ's import barriers, the advent of
CER, and the government's determination to price energy at the replacement
cost rather than the historical production cost.
As far as specific developments are concerned, what is emerging is that
there are no universally applicable solutions or techniques, although there
are some areas where certain options are likely to be profitable. For
example, it is not a case of photocell lighting control being better than
occupant sensing lighting control, rather that they are both good ways of
controlling lights in different situations. Similarly no computerised
Energy Management and Control System (EMCS) is likely to be the answer to
managing every building. Rather a range of systems is emerging,
appropriate for a wide range of different buildings. Increasingly these
systems will use simpler user-friendly software, enabling them to be
tailored for particular buildings.
The development of networked modular systems and the possible penetration
of innovative financing arrangements and bureau and management services
should make the financial advantages of energy management available to an
ever increasing number of buildings. These developments will also offer
considerable business opportunities for financiers, suppliers, importers,
manufacturers, installers, commissioning specialists, consultants, building
owners and managers, and of course tenants.
Thrre is every reason to believe that the development of EMCS is proceeding
in a similar fashion to micro and personal computers, but with a 5 to 10
year time lag. Therefore we can expect the market to be dominated
eventually by a small number of agressive manufacturers who will set the
industry standards for system and software compatibility, as IBM and Apple
are doing with Personal Computers. Great care should be exercised that
systems purchased come from manufacturers likely to remain in business and
who will continue to provide hardware and software support - this does not
necessarily include the current industry giants!
The one certain thing about future developments is that they will turn out
to be somewhat different than expected at present. Future systems will
definitely do more and cost less than currently available systems.
Therefore systems offering long paybacks will probably be overtaken by
developments before they have fully paid for themselves. However, there is
no doubt that in medium to large buildings energy management is profitable
now, and it will become more profitable, not less.
6. ACKNOWLEDGEMENTS
Princival acknowledgements must go to the Building Research Association of
providing the author with a study
New Zealand (BRANZ)-~O~so
award to travel overseas and examine at first hand developments in building
energy management and low energy lighting systems.Without their assistance
this paper would never have been written. The New Zealand Energy Research
and Development Committee and the Ministry of Energy should be thanked for
their valued funding of research into energy use in the Wellington CBD
which led to the interest in energy management.
I should like to give special thanks to Dr George Baird, the Director of
the Energy Research Group at VUW, SoA for his invaluable support in
applying for and taking up the BRANZ Study Award. Finally I would like to
acknowledge the considerable encouragement and assistance of my colleagues
at the School of Architecture, and thank Linda Searle and Gavin Woodward
for their help in preparing this paper.
~ 1 9
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t
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BUILDING RESEARCH ASSOCIATION OF NEW ZEALAND INC.
HEAD OFFICE AND LIBRARY, MOONSHINE ROAD, JUDGEFORD.
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