Report for Surrey County Council on actions to save energy

1. Surrey County Council – Opus II
Proposal for a
Improvements in energy performance
At
Surrey County Council
Opus II, Leatherhead
To:
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2. Surrey County Council – Opus II
Surrey County Council Project Ref: Q003072/DB
County Hall Date- 12/10/2009
Penrhyn Rd Project:- Opus II
Kingston upon Thames,
Surrey
KT1 2DN
Dear Keith,
UNDER THIS PROPOSAL WE WILL:
Examine and report on:-
The use of the building in general and architecture.
The equipment, its function, and integrated behaviours.
Human factors.
This will allow us to contrast and compare the current situation with the proposals and
select those that achieve the best return on investment.
Yours sincerely,
Kieron Ryan
Energy and Control Systems
Schedule of Contents
The building.......................................................................................................................................................4
Architecture.......................................................................................................................................................4
Usage.................................................................................................................................................................4
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3. Surrey County Council – Opus II
SYSTEMS..........................................................................................................................................................5
Lighting Controls...............................................................................................................................................5
LTHW.................................................................................................................................................................5
Chiller................................................................................................................................................................5
FCU...................................................................................................................................................................5
OBSERVATIONS ON THE DAY ................................................................................................................................7
Integration.........................................................................................................................................................7
Human Factors..................................................................................................................................................7
ENERGY PROPOSAL.............................................................................................................................................9
Airside Systems..................................................................................................................................................9
LTHW System.....................................................................................................................................................9
Lighting System.................................................................................................................................................9
Chillers..............................................................................................................................................................9
PROPOSAL SYNOPSIS.........................................................................................................................................10
1. Re-commissioning Costs..............................................................................................................................10
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4. Surrey County Council – Opus II
Overview.
The building
The building consists of three storeys plus a small basement area for the LTHW
plantroom. There is an exterior enclosure containing the chiller and air handling unit.
The building was constructed in the late 1980s.
Architecture
Faced with Kingscourt Hanover Multi bricks (or similar) and interior lined with block
work to create a cavity for insulation. Windows are small double glassed aluminium
framed and have a solar reflective coating representing 40%-50% of the total vertical
surface.
The roof is of a tiled and pitched construction with two small a flat areas traversing the
apex. the majority of the smaller area is glass whilst the majority of the larger area is
flat and has a small atrium.
The Building would have a footprint of 900 sqm per occupied floor (2700sqm total)
plus approx 20sqm at basement level. However the 3 rd floor is significantly smaller
and is assumed to be half.
Total 900+900+450 + 20 = 2270sqm approx.
The geography of the building is unlikely to be modified. Any expansion of the building
Is likely to impact on the car park to the rear. This resource is fully utilized at present.
Usage
The building functions as a general administrative facility. The building is entered via a
entrance lobby to the rear adjacent to the car park with significant glass façade and
faces West.
The entrance doors are security controlled and of the swing type, providing control of
the egress of tempered air from the lobby. The lobby is the main thoroughfare
containing access to the ground floor rooms and stairs to other levels.
The ground floor is divided by interior partitions in to a variety of smaller offices with
control of the HVAC systems and lights being defined by the size and occupancy of
the space. The first and second floors can be accessed from the staircase located in
the lobby. These floors are similar to the ground floors in that they are partitioned in to
sub offices with some additional open plan facilities.
The core use the building is unlikely to change, remaining as an administrative office
for the district.
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5. Surrey County Council – Opus II
Systems
Lighting Controls
Some space lighting has been modified to incorporate other standalone lighting
circuits in order to meet the partitioned space requirement.
A smart lighting system is installed (Phillips ECS network controllers in the risers) this
appears to be a low cost installation under a separate capital project.
There is no method of communicating with the lighting controllers (located In the
risers) and therefore our costs to optimise the energy reductions using the existing
system is limited.
LTHW
Located in the basement is the low temperature hot water (LTHW) plant, chiller
pumps and Motor control centre (MCC).
The plant is in good condition and has been well maintained. During the site visit we
did not observe an unserviceable equipment.
The LTHW system consists of 2 water pressurisation units feeding the LTHW and
CHW services. The LTHW circuit consists of 3 off 102 Kw boilers (306Kw total) and 2
pumps 0.75 Kw each (in duty/standby twin head configuration).
A constant temperature circuit provides LTHW to the AHU reheat batteries. However,
it is apparent that the pipe work travels vertically up the risers suggesting that this
circuit also provides LTHW to the FCU and although this circuit should be scheduled
with outside air, this was not apparent as the LTHW supply temperature is running at
60°C with an ambient temperature of 16°C.
It is then left to the down stream controls to draw what is required for local adjustment.
A VT circuit is used to provide perimeter heating. We where unable to determine the
temperature of the circuit and will assess the control of this circuit as part of the wider
impact implied by the failing building control system.
Chiller
The chiller operates under it’s own controls accepting a simple “enable” signal from
the Landis and Staefa controller. The chiller then targets a setpoint, nominally 6°C
flow and 12°C return. There is no load prediction and therefore the system supplies
the complete loop with CHW for the entire period of operation.
FCU
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6. Surrey County Council – Opus II
The FCU for the distributed local control for each space. Each unit, and some groups,
are controlled by wall mounted Honeywell thermostats (6360 type A or B) having a
separate heating and cooling outputs. The units have no network communications
and are powered through two contactors located in the risers providing time control in
large groups, an occupancy switch on each floor provides an extension period acting
on these large groups
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7. Surrey County Council – Opus II
Observations on the day
The space temperature is 25.3°C . 1
The LTHW Flow is 59.6°C 2
The LTHW Return is 27.3°C
The space temperature is high.
The flow temperature is unnecessarily high given the ambient temperature.
The flow temperature is not scheduled with outside air as this should be lower, we
suggest, 60°C water is available at 10°C and a slope is instigated such that heating
ceases above 20°C both points should be programmable via a suitable interface.
The difference between LTHW Flow and return (32.3°C) suggests that down stream
from the boilers, there is a significant demand for heating.
Whilst on the site visit I observed that of the majority of offices are warm and that the
25.3°C “space temperature” was not unrealistic throughout the building. Having
manual controls on the FCU can cause occupiers to change setpoints from one
extreme to the other, that is heating on cooler days and cooling on warmer days, in
reality the difference may be trivial but the perception and consequential action has a
significant impact on energy consumption especially in summer where cooling is
expected. Cooling is more expensive and uses more energy than heating.
Integration.
The single landis and Staefa controller of offers no integration between controllers as
no other intelligent controllers are present.
The mechanical systems operate as standalone devices operating to achieve a single
unrelated parameter
i.e. Boilers provide 60°C of water, AHU supply tempered air at 21°C, chiller provides
water at 6°C, FCU maintain 25°C in the space.
The FCU use standalone controls and are not connected to each other or to the main
controller.
The Chiller plant receives a simple enable signal and provides control of the flow and
return water temperatures.
The lighting controls are self contained operating on the their own time schedule
contained within the lighting controllers, currently inaccessible.
Human Factors
1 Some sensors are located around the building for this purpose because the FCU are standalone and
therefore can not contribute.
2 Approaching Boiler max flow temp.
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8. Surrey County Council – Opus II
Time schedules programmed as part of the original installation, are unlikely to be
energy efficient with regards to current usage.
The accessibility of local setpoints will always cause a degree of disturbance in the
plant and the environment because each individual will perceive a different
environmental condition.
The manual intervention during the spring and autumn periods causes aberrations in
the energy consumption of the building the human factor is vulnerable to over or
under compensation of the required conditions.
The inaccessibility of the lighting control system means that the system is not adjusted
to meet current and future requirements.
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9. Surrey County Council – Opus II
Energy Proposal
Airside Systems
The AHU provides fresh, tempered air to the FCU. The implication is that it is
configured to supply air at some constant temperature. However the AHU is a
recirculation type and this means that there will be several distinct possibilities to the
function of the AHU contained within the Landis and Staefa controller.
There are several aspects to the AHU that would create immediate energy savings,
fan speed control based on the volume of fresh air required, scheduling of the
supply temperature with respect to outside air, improvements in the use of the
recirculation dampers.
Connectivity to an LTHW demand prediction algorithm can be used to further
reduce demand across the system.
The FCU thermostat controls should be set and locked to agreed set points, if
two FCU serving the same space are referencing different setpoints you will find that
one will be achieve 100% cooling and the other 100% heating due to contradicting
objectives caused by the internal controls in each.
LTHW System
Many LTHW valves on the FCU are likely to be open, this could be a fault and all
FCU heating and cooling valves should be investigated for functionality.
The AHU and FCU are placing an unnecessary load on the LTHW system in order to
achieve the programmed supply temperature, the AHU should be re-commissioned
and reference values reset as appropriate.
Lighting System
Lighting systems lack an interface and drawings to define the function of the
numerous switches around the building.
The lighting system should be reviewed and re-commissioned to meet the
current requirements, this would create an opportunity to update the system and
integrate each space across the lighting and HVAC systems.
Many of the lighting tubes, fittings and controls on not as efficient as they could be.
Modern light fittings allow for significant energy reductions however this comes at a
cost to the business and some degree of inconvenience. Further investigation
would be worthwhile and will form part of our discussions with Phillips lighting
Solutions.
Chillers
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10. Surrey County Council – Opus II
Two aspects are offered as energy savings. Reconfigure the chiller to implement
an predictive algorithm. That is, the flow and return are analysed to determine if the
existing status (say, 75% load) is appropriate to meet future demand
This algorithm optimises the run hours by ensuring that compressor 1 operates at
maximum efficiency as long as possible before calling compressor 2
The time schedule will require reconfiguration and should only provide an enable
when outside conditions are not capable of meeting the requirements. That is, the
AHU and chiller form part of the intelligence of the building, providing colder
fresh air in Winter negates the requirement for the chiller.
Proposal Synopsis
Generally the Landis and Staefa controller is adrift from the optimal design
parameters.
There are to options:-
1. re-commission the existing controls to meet existing requirements
2. Replace the existing controls
1. Re-commissioning Costs
Re-commissioning of the existing controls; nominally 3 weeks work
Initial survey to establish detailed scope £X,XXX (3 days)
Will be deducted from an order to complete the works.
Re-commissioning of equipment £XX,000 2 weeks
I have included a nominal sum to include the lighting which is subject to further
detailed review with Phillips to define exactly what is achievable
If we where to consider our remote monitoring services:-
Lighting times, Lighting groups, chiller setpoints, AHU setpoints, LTHW setpoints and
time schedules etc are likely to be incorrectly set to achieve the current functionality
required of the building because access to the lighting and controls is hampered by a
lack of information from the original installation.
Fore Example; the need to manually turn off the boilers in spring and autumn in order
to limit the LTHW temperature.
Documentation on the original installation configuration and user manuals do not
support the current installation in full due to continuous site development to the
system, input device failure is a possibility and design setpoint retention is unlikely to
meet the current use.
This is supported by high internal space temperatures, all boilers functioning at their
internal setpoint of 60°C, pumps and fans at full speed, a lack of access to time
schedules (allowing for automated on/off controls).
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