Proposal For Scc Opus II

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Report for Surrey County Council on actions to save energy

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Proposal For Scc Opus II

  1. 1. Surrey County Council – Opus II Proposal for a Improvements in energy performance At Surrey County Council Opus II, LeatherheadTo: Page 1 of 10 18/01/11
  2. 2. Surrey County Council – Opus IISurrey County Council Project Ref: Q003072/DBCounty Hall Date- 12/10/2009Penrhyn Rd Project:- Opus IIKingston upon Thames,SurreyKT1 2DNDear 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 andselect those that achieve the best return on investment.Yours sincerely,Kieron RyanEnergy and Control SystemsSchedule of Contents The building.......................................................................................................................................................4 Architecture.......................................................................................................................................................4 Usage.................................................................................................................................................................4 Page 2 of 10 18/01/11
  3. 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 Page 3 of 10 18/01/11
  4. 4. Surrey County Council – Opus IIOverview. The buildingThe building consists of three storeys plus a small basement area for the LTHWplantroom. There is an exterior enclosure containing the chiller and air handling unit.The building was constructed in the late 1980s. ArchitectureFaced with Kingscourt Hanover Multi bricks (or similar) and interior lined with blockwork to create a cavity for insulation. Windows are small double glassed aluminiumframed and have a solar reflective coating representing 40%-50% of the total verticalsurface.The roof is of a tiled and pitched construction with two small a flat areas traversing theapex. the majority of the smaller area is glass whilst the majority of the larger area isflat 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 smallerand 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 buildingIs likely to impact on the car park to the rear. This resource is fully utilized at present. UsageThe building functions as a general administrative facility. The building is entered via aentrance lobby to the rear adjacent to the car park with significant glass façade andfaces West.The entrance doors are security controlled and of the swing type, providing control ofthe egress of tempered air from the lobby. The lobby is the main thoroughfarecontaining 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 withcontrol of the HVAC systems and lights being defined by the size and occupancy ofthe space. The first and second floors can be accessed from the staircase located inthe lobby. These floors are similar to the ground floors in that they are partitioned in tosub offices with some additional open plan facilities.The core use the building is unlikely to change, remaining as an administrative officefor the district. Page 4 of 10 18/01/11
  5. 5. Surrey County Council – Opus IISystems Lighting ControlsSome space lighting has been modified to incorporate other standalone lightingcircuits in order to meet the partitioned space requirement.A smart lighting system is installed (Phillips ECS network controllers in the risers) thisappears to be a low cost installation under a separate capital project.There is no method of communicating with the lighting controllers (located In therisers) and therefore our costs to optimise the energy reductions using the existingsystem is limited. LTHWLocated in the basement is the low temperature hot water (LTHW) plant, chillerpumps and Motor control centre (MCC).The plant is in good condition and has been well maintained. During the site visit wedid not observe an unserviceable equipment.The LTHW system consists of 2 water pressurisation units feeding the LTHW andCHW services. The LTHW circuit consists of 3 off 102 Kw boilers (306Kw total) and 2pumps 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 thiscircuit also provides LTHW to the FCU and although this circuit should be scheduledwith outside air, this was not apparent as the LTHW supply temperature is running at60°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 thetemperature of the circuit and will assess the control of this circuit as part of the widerimpact implied by the failing building control system. ChillerThe chiller operates under it’s own controls accepting a simple “enable” signal fromthe Landis and Staefa controller. The chiller then targets a setpoint, nominally 6°Cflow and 12°C return. There is no load prediction and therefore the system suppliesthe complete loop with CHW for the entire period of operation. FCU Page 5 of 10 18/01/11
  6. 6. Surrey County Council – Opus IIThe 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 aseparate heating and cooling outputs. The units have no network communicationsand are powered through two contactors located in the risers providing time control inlarge groups, an occupancy switch on each floor provides an extension period actingon these large groups Page 6 of 10 18/01/11
  7. 7. Surrey County Council – Opus IIObservations on the dayThe space temperature is 25.3°C . 1The LTHW Flow is 59.6°C 2The LTHW Return is 27.3°CThe 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, wesuggest, 60°C water is available at 10°C and a slope is instigated such that heatingceases 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 streamfrom 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 the25.3°C “space temperature” was not unrealistic throughout the building. Havingmanual controls on the FCU can cause occupiers to change setpoints from oneextreme to the other, that is heating on cooler days and cooling on warmer days, inreality the difference may be trivial but the perception and consequential action has asignificant impact on energy consumption especially in summer where cooling isexpected. Cooling is more expensive and uses more energy than heating. Integration.The single landis and Staefa controller of offers no integration between controllers asno other intelligent controllers are present.The mechanical systems operate as standalone devices operating to achieve a singleunrelated parameteri.e. Boilers provide 60°C of water, AHU supply tempered air at 21°C, chiller provideswater 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 maincontroller.The Chiller plant receives a simple enable signal and provides control of the flow andreturn water temperatures.The lighting controls are self contained operating on the their own time schedulecontained within the lighting controllers, currently inaccessible. Human Factors1 Some sensors are located around the building for this purpose because the FCU are standalone andtherefore can not contribute.2 Approaching Boiler max flow temp. Page 7 of 10 18/01/11
  8. 8. Surrey County Council – Opus IITime schedules programmed as part of the original installation, are unlikely to beenergy efficient with regards to current usage.The accessibility of local setpoints will always cause a degree of disturbance in theplant and the environment because each individual will perceive a differentenvironmental condition.The manual intervention during the spring and autumn periods causes aberrations inthe energy consumption of the building the human factor is vulnerable to over orunder compensation of the required conditions.The inaccessibility of the lighting control system means that the system is not adjustedto meet current and future requirements. Page 8 of 10 18/01/11
  9. 9. Surrey County Council – Opus IIEnergy Proposal Airside SystemsThe AHU provides fresh, tempered air to the FCU. The implication is that it isconfigured to supply air at some constant temperature. However the AHU is arecirculation type and this means that there will be several distinct possibilities to thefunction 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 thesupply temperature with respect to outside air, improvements in the use of therecirculation dampers.Connectivity to an LTHW demand prediction algorithm can be used to furtherreduce demand across the system.The FCU thermostat controls should be set and locked to agreed set points, iftwo FCU serving the same space are referencing different setpoints you will find thatone will be achieve 100% cooling and the other 100% heating due to contradictingobjectives caused by the internal controls in each. LTHW SystemMany LTHW valves on the FCU are likely to be open, this could be a fault and allFCU heating and cooling valves should be investigated for functionality.The AHU and FCU are placing an unnecessary load on the LTHW system in order toachieve the programmed supply temperature, the AHU should be re-commissionedand reference values reset as appropriate. Lighting SystemLighting systems lack an interface and drawings to define the function of thenumerous switches around the building.The lighting system should be reviewed and re-commissioned to meet thecurrent requirements, this would create an opportunity to update the system andintegrate 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 acost to the business and some degree of inconvenience. Further investigationwould be worthwhile and will form part of our discussions with Phillips lightingSolutions. Chillers Page 9 of 10 18/01/11
  10. 10. Surrey County Council – Opus IITwo aspects are offered as energy savings. Reconfigure the chiller to implementan predictive algorithm. That is, the flow and return are analysed to determine if theexisting status (say, 75% load) is appropriate to meet future demandThis algorithm optimises the run hours by ensuring that compressor 1 operates atmaximum efficiency as long as possible before calling compressor 2The time schedule will require reconfiguration and should only provide an enablewhen outside conditions are not capable of meeting the requirements. That is, theAHU and chiller form part of the intelligence of the building, providing colderfresh air in Winter negates the requirement for the chiller.Proposal SynopsisGenerally the Landis and Staefa controller is adrift from the optimal designparameters.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 weeksI have included a nominal sum to include the lighting which is subject to furtherdetailed review with Phillips to define exactly what is achievableIf we where to consider our remote monitoring services:-Lighting times, Lighting groups, chiller setpoints, AHU setpoints, LTHW setpoints andtime schedules etc are likely to be incorrectly set to achieve the current functionalityrequired of the building because access to the lighting and controls is hampered by alack of information from the original installation.Fore Example; the need to manually turn off the boilers in spring and autumn in orderto limit the LTHW temperature.Documentation on the original installation configuration and user manuals do notsupport the current installation in full due to continuous site development to thesystem, input device failure is a possibility and design setpoint retention is unlikely tomeet the current use.This is supported by high internal space temperatures, all boilers functioning at theirinternal setpoint of 60°C, pumps and fans at full speed, a lack of access to timeschedules (allowing for automated on/off controls). Page 10 of 10 18/01/11

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