Technical guides for owner/manager of an air conditioning                    system: volume 10    Successful Case Studies ...
Team                                   France (Project coordinator)                                    Armines - Mines de ...
CONTENTSSCOPE OF THE PROJECT ...................................................................................4INTRODUCT...
SCOPE OF THE PROJECTThe Propose of the AuditACThe aim is to demonstrate how much advantage can be taken from the implement...
Research Center                                                                                                           ...
Case studies will concern different sizes and types of buildings, which are classified bybuilding type (functionality) and...
-     VRF                                                    -     Heat Pump                                              ...
BCS 2 – Brussels                     Case: This case is about a 13 story office building.                     Installed HV...
SCS 1 – Maribor                     Case: This case relates a high efficient system for an office building. At            ...
UKCS 5 – Cardiff                     Case: This case study aimed at assessing the energy performance and its              ...
UKCS 9 – London                      Case: This case study aimed at assessing the energy performance and its              ...
ICS 3 – Oderzo                            Case: This case is about a 3-storey hospital building.                          ...
PCS 1 – Porto:Case: This case is about a computer center existing in the Faculty ofEngineering of Porto University. The ro...
ACS 1 – SalzburgCase: This case relates the energy consumption changes in a new archivebuilding along with the years and w...
WELL DOCUMENTED CASE STUDIESTwenty Six case studies were analyzed. Among these, 6 were considered to be the welldocument c...
•   In summer the indoor comfort is more challengingSolutions – Major ModificationsThe solution proposed is, in energetic ...
As it is verified the energy earnings, of the floor -1, with the substitution of the currentsystem for the proposed, they ...
Office Building • MariborThe energy system of an office business building is presented, where at minimal energyconsumption...
The basic heat source is underground water. In winter it has a temperature around 10-13°C,o on the other side, we have the...
Office Building • BrusselsDescription:This is a medium size office building (28 000 m2) erected in centre of Brussels at e...
Accomplished improvements and Retrofit Opportunities:An attempt of free chilling was done sometime ago, by adding a water-...
Archive Building • SalzburgDescription:This case study relates to a building built in 2003/04. This building has it the en...
Cultural Building • TurinDescription:The building of the culture department is situated in the historic centre of Turin ha...
Proposed Solutions:Change the embedded floor radiant panels to fan-coils. The new HVAC system can stillbe defined as air/w...
Archway House – Office Building • CardiffDescriptionThis building, located in Cardiff-Wales, is an office building with th...
From the breakdown analysis it can be concluded that the following ECOs could be usedto help reduce the cooling energy dem...
RESULTS AND ENERGY POTENCIAL IMPROVESGeneral energy ImprovesIn general overview, the observed potential energy savings in ...
Some audit cases had energy improvements only with a new lighting strategy control, forexample the PCS-31 the reduction th...
DETAILED INFORMATION FOR AC CASE STUDIESAustrian Case Study 1ACS1City Archive                                             ...
Design DetailsThe regulation system of the company controls 9 different storage areas and providesthis information to the ...
Austrian Case Study 2ACS2Hospital                                                          Georg Benke                    ...
The 6 piston compressors were replaced by 6 Screw compressors(Schraubenkompressoren), which have up to 40 % more cooling c...
Belgium Case Study 1BCS1Office Building                                                          Corinne ROGIEST-LEJEUNE  ...
Figure 2: sketch of the building at design stageDescription of the building layout:       Two big (300 meters long) rectan...
+ reinforced concrete                  U=0.47 W/m²Koffice floor: heavy reinforced concrete +light concrete +linoleum      ...
In the offices:                                Figure 7: view of the terminal unitsAbout 1 500 terminal units with VAV (Va...
For group S1 and N1, the AHU feeds the offices with fresh air at fixed air volume (4300m³/h) and re-circulated air with va...
3 or 4 oil cooler (one per compressor)        3 or 4 filters (one per compressor)Both chillers use two independent refrige...
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Auditac tg10 case studies

  1. 1. Technical guides for owner/manager of an air conditioning system: volume 10 Successful Case Studies in AuditAC 1
  2. 2. Team France (Project coordinator) Armines - Mines de Paris Austria Slovenia Austrian Energy Agency University of Ljubljana Belgium UK Université de Liège Association of Building Engineers Italy BRE Politecnico di Torino (Building Research Establishment Ltd) Portugal University of Porto Welsh School of Architecture Eurovent-CertificationAuthors of this volumeJosé Luís ALEXANDRE (University of Porto, Portugal)André POÇAS (INEGI, Portugal)Emanuel SÁ (INEGI, Portugal) The sole responsibility for the content of this publication lies with the authors. It doesnot represent the opinion of the European Communities. The European Commission isnot responsible for any use that may be made of the information contained therein. 2
  3. 3. CONTENTSSCOPE OF THE PROJECT ...................................................................................4INTRODUCTION OF CASE STUDIES ..................................................................4HIGHLIGHTS FROM CASE STUDIES..................................................................7Office Buildings ............................................................................................................................................ 7Hospital Buildings .......................................................................................................................................11Commercial Building ..................................................................................................................................12Other Service Buildings ..............................................................................................................................12WELL DOCUMENTED CASE STUDIES..............................................................15RESULTS AND ENERGY POTENCIAL IMPROVES............................................27General energy Improves............................................................................................................................27Equipment Replacement.............................................................................................................................28DETAILED INFORMATION FOR AC CASE STUDIES .......................................29 3
  4. 4. SCOPE OF THE PROJECTThe Propose of the AuditACThe aim is to demonstrate how much advantage can be taken from the implementationof the inspection of air conditioning systems. More than the inspection itself, the projectpromotes audit procedures as the real and effective method to reach such energysavings.The inspection characteristics are analyzed and an effort is made, in collaboration withthe European standardization body CEN, to modify and adapt the standard inspectionfor detecting actual system’s problems.A number of tools are developed to help auditors; inspectors and energy managersidentify the most important energy conservation opportunities in existing AC systemsand to avoid the most common errors that lead to a waste of energy.Moreover, AuditAC attempts to reach all actors of the air-conditioning market(manufacturers, installers, maintenance staff, etc.), in order to involve them in theprocedure of equipment auditing, make the audit procedure easier and, furthermore,improve the acceptance of the audit itself.Throughout all project a database called AUDIBAC was developed for the buildingowners and respective systems. This data base will inform the users about the bestsolution to increase the efficiency in what concerns to energy of the buildings system. Itis a tool of great importance for the effective accomplishment of the auditing proceduresin AC systems. This tool will be responsible for the creation of results in line with theEPBD requirements, from the viewpoint of both the customer and the auditor.INTRODUCTION OF CASE STUDIESTo develop this data base, it became extremely necessary to know well different casesof application of air conditioned systems at a European level. In fact that Europe presentdifferent climatic areas and consequently different types of building envelope turns theknowledge of the system operation for each case very important. The case studies forthe database were developed by the several partners in the AuditAC project, Austria,Belgium, France (project coordinator), Italy, Portugal e Slovenia and UK. 4
  5. 5. Research Center Cultural Dpt. Commercial Auditorium Informatics Laboratory Hospital Archive Library OfficeNo Name and Location 1 ACS-1 Salzburg, Austria ● 2 ACS-2 Linz, Austria ● 3 BCS-1 Namur, Belgium ● 4 BCS-2 Brussels, Belgium ● 5 BCS-3 Liège, Belgium ● 6 FCS-1 Orleans, France ● 7 FCS-2 Paris, France ● 8 ICS-1 Turin, Italy ● 9 ICS-2 Vercelli, Italy ●10 ICS-3 Oderzo, Italy ●11 ICS-4 Bologna, Italy ●12 PCS-1 Porto, Portugal ●13 PCS-2 Porto, Portugal ●14 PCS-3 Porto, Portugal ●15 PCS-4 Porto, Portugal ●16 PCS-5 Porto, Portugal ●17 SCS-1 Maribor, Slovenia ●18 UKCS-1 Leicester, UK ●19 UKCS-2 Westminster, UK ●20 UKCS-3 Cardiff, UK ●21 UKCS-4 Cardiff, UK ●22 UKCS-5 Cardiff, UK ●23 UKCS-6 Oxford, UK ●24 UKCS-7 London, UK ●25 UKCS-8 London, UK ●26 UKCS-9 London, UK ● 5
  6. 6. Case studies will concern different sizes and types of buildings, which are classified bybuilding type (functionality) and by type of HVAC system. This classification makespossible the comparison between the different case studies and allow for the first time toestimate on a statistical basis the magnitude of the gains possible on European A/Cinstallations as well as to give a list of possible malfunctions of the equipment, which theauditor can probably find during the audit phase.Building type Classification: Office buildings (O) Hospitals (H) Commercial (C) Other Service Buildings (S)HVAC system Classification: Centralized Primary system (PS) - Chiller - Boiler - Heat Pump - Thermal Storage Secondary system (SS) - Air base system - Water based system Non Centralized DX system - Split - Multi Split 6
  7. 7. - VRF - Heat Pump UKCS-2 - Westminster UKCS-7 - London UKCS-8 - London UKCS-9 - London UKCS 1 Leicester UKCS-3 - Cardiff UKCS-4 - Cardiff UKCS-5 - Cardiff UKCS-6 - Oxford ACS-1 - Salzburg BCS-2 - Brussels FCS – 1 Orleans SCS – 1 Maribor ICS-2 - Vercelli ICS-3 - Oderzo PCS-1 - Porto BCS-3 - Liege BCS 1 Namur PCS-2 - Porto PCS-3 - Porto PCS-4 - Porto PCS 5 - Porto ACS-2 - Linz ICS-1 - Turin FCS-2 - Paris O O O O O H H H S S S S S S O S S O C O O O O O O - Chiller • • • • • • • • • • • • - Boiler • • • • • • PS - Heat pump •HVAC System Type Centralized - Thermal storage • • - Air based system • • • • • • • • • • • • • • SS - Water based system • • • • • • • • • • Not Centralized - Split • • • - Multi Split • DX system - VRF • • • • • - Heat pump • HIGHLIGHTS FROM CASE STUDIES Office Buildings BCS 1 – Namur Case: This case aimed at assessing and managing the HVAC system installed in an office building located in the center of the town of Namur. Installed HVAC system: Heating – three gas boilers with variable flow to feed radiators and AHU’s. Cooling – two chillers with reciprocating compressors and air condensers with variable flow to feed AHU’s and fan- coils. HVAC system modifications: During the audit phase the cooling and ventilation performances were not as expected. Alteration of the control strategy, the implementation of new parameters and administration rules, the regulation of the set points and of the VAV boxes thermostats were some of the modifications for this case. Lessons learned: After commissioning, most of the errors were eliminated but some of the problems continue to exist. Modeling some retrofit opportunities can increase further more the heating and cooling performances of the installed system. 7
  8. 8. BCS 2 – Brussels Case: This case is about a 13 story office building. Installed HVAC system: The installed HVAC system is composed by 4- pipe terminal units, AHU’s, Chiller, boiler, cooling towers and circulation pumps. HVAC system modifications: There are some suggestions made in order to improve the system performance. The AHU’s were partially renovated and all induction units and thermostatic valves were replacement. The replacement of existing induction units by more efficient devices (other induction units or fan coils), should make possible to run the system with higher chilled water temperature and therefore better COP. Lessons learned: Other options can always be considered to improve the systems efficiency; even small ones can produce a big effect when you have a big building with a large system. FCS 1 – Orleans Case: This case is about a refrigeration plant of a commercial company. They started having problems with the high energy bills, so the target to start reducing the energy consumption was the cooling production unit. Installed HVAC system: The system installed was composed by centrifugal compressors groups functioning in stages. This system was oversized andNO PHOTO AVAILABLE used forbidden refrigerant according with the actual regulations. HVAC system modifications: The modifications consisted on the substitution of the cold production unit by one other, adapted to the cold demand and modulated in stages. Lessons learned: The real saving reached 56 % of the electricity from the cold production groups. FCS 2 – Paris Case: audit preformed to an office building located in the Paris suburbs. The building has one floor and a basement. Its overall clear surface is 1140 m ². The building can be divided into three types of spaces: circulation zones, conference offices and rooms. Installed HVAC system: The five conference rooms are climatized by an AHU and a group of cold water production. About thirty offices have AC based on 2-pipe fancoils and natural ventilation. The cold water that feeds the loop of the AHU and the fancoil is produced in a non-reversible alternative Chiller. The system operates 24 h /24 and 7 days/7. HVAC system modifications: Two main improvement scenarios were foreseen: the first scenario consist in keeping air conditioning in summer and the heating with Joule effect in winter; the second scenario would be the replacement of the refrigeration unit by a reversible heat pump with an average seasonal COP of 2,5. Associated with these two scenarios other measures were proposed in order to reduce the energy consumption: Change the water loop set points, change the functioning schedules, reduce the internal gains etc. Lessons learned: This study shows that the improvement scenarios combined with other measures can result in a decrease from 30% to 77% of the HVAC system energy consumption. 8
  9. 9. SCS 1 – Maribor Case: This case relates a high efficient system for an office building. At minimal energy consumption, thermal comfort and good work conditions are achieved. The investment costs are similar with the traditional buildings. Installed HVAC system: The building is heated with a combined heat-pump (water-water) which provides heating and cooling energy. As a support for heating there is also a low temperature condensing gas boiler. Whole space is ventilated with high energy efficient ventilation / air conditioning units with energy recovery more than 90%. There is also a possibility of direct cooling with ground water. In summer period, it has a temperature of 15 – 16ºC. HVAC system modifications: This study only intents to present a case of good performance, so there are no modifications. Lessons learned: It is possible to have a high efficient HVAC and obtain good levels of comfort without much more than an usual building. UKCS 1 – Leicester Case: This case illustrates an exceptionally energy efficient/low energy air conditioning system. This is a 4 storey office building. Installed HVAC system: The HVAC cooling system consists on chilled beams. The cold water production unit is a package air cooled chilled usingNO PHOTO AVAILABLE R407c as refrigerant. HVAC system modifications: There are no modifications suggested Lessons learned: This building seems to be very energy efficient according 2 to is overall annual energy consumption/m when compared to national benchmarks. UKCS 2 – Westminster Case: This case study aimed at assessing the energy performance and its potential for improvement, of a comfort cooling system installed in a UK office building. The building comprises six-storeys (Ground plus 5) of mainly small cellular offices and a lower ground containing support and storage areas. Installed HVAC system: The basic system configuration features passive chilled ceilings and perimeter passive beams with night-time ice storage andNO PHOTO AVAILABLE some DX systems serving computer rooms and conference suites. Ventilation is provided mechanically via centralised AHU’s and heating is provided by perimeter radiators. HVAC system modifications: This case study focus on the actual system analysis, thus no modifications were implemented. Lessons learned: Detail thermal simulation tool can be very helpful to predict HVAC system consumption and consequently avoid some errors in the project or correcting them during an Audit. UKCS 3 – Cardiff Case: This case study compares the energy consumption values obtained using thermal simulation tools such as EnergyPlus with real energy measurements. Installed HVAC system: The HVAC system installed is a 2-pipe Multi-Split DX system. This system has the possibility to free cool the spaces. HVAC system modifications: This study focus on the actual system analysis, thus no modifications were tested. Lessons learned: Detailed thermal simulation tool can be very helpful to predict HVAC system consumption and consequently avoid some errors in the project. 9
  10. 10. UKCS 5 – Cardiff Case: This case study aimed at assessing the energy performance and its potential for improvement, of a comfort cooling system installed in a small administrative office, located in a historic building of Cardiff University. Installed HVAC system: The office has a DX split comfort cooling systemNO PHOTO AVAILABLE with a roof mounted condenser and a 4-way ceiling mounted cassette. HVAC system modifications: This case study focus on the actual system analysis, thus no modifications were implemented. Lessons learned: Detail thermal simulation tool can be very helpful to predict HVAC system consumption and consequently avoid some errors in the project or correcting them during an Audit. UKCS 6 – Oxford Case: This case study aimed at assessing the energy performance and its potential for improvement, of a comfort cooling system installed in a light industrial building on a small rural estate near Oxford. The conditioned area consists of a large open plan office, 3 cellular spaces of executive offices, a conference room and a production area room. Installed HVAC system: This area is serviced by VRF indoor units, ceiling mounted, from external condensers on a 2-pipe heating and cooling “changeNO PHOTO AVAILABLE over” only basis. The supply AHU consist of an in-duct axial fan, filter pack and electric heater battery. The system has plenum return ventilation with ducted supply and partial recirculation in the fan-coil units. HVAC system modifications: This case study focus on the actual system analysis, thus no modifications were implemented. Lessons learned: Detail thermal simulation tool can be very helpful to predict HVAC system consumption and consequently avoid some errors in the project or correcting them during an Audit. UKCS 7 – London Case: This case study aimed at assessing the energy performance and its potential for improvement, of a comfort cooling system installed in the ground floor of a 2 storey office block. The conditioned area consists of open plans and cellular office rooms, meeting rooms, training rooms and a reception. Installed HVAC system: The conditioned area has a 2-pipe fan-coil system with the electrical reheat, supplied by two reverse cycle air-cooled chillers.NO PHOTO AVAILABLE The indoor units are a 2-pipe ceiling mounted cassettes with multi-speed fans and electrical reheat in the perimeter units. HVAC system modifications: This case study focus on the actual system analysis, thus no modifications were implemented. Lessons learned: Detail thermal simulation tool can be very helpful to predict HVAC system consumption and consequently avoid some errors in the project or correcting them during an Audit. UKCS 8 – London Case: This case study aimed at assessing the energy performance and its potential for improvement, of a comfort cooling system installed in the first floor of a 2 storey office block. The conditioned area consists of open plans and cellular office rooms, meeting rooms. Installed HVAC system: 3 pipe heat recovery VRF units with roof mounted condensers and internal ceiling mounted cassettes. The cassettes draw air from the ceiling void that is also supplied with fresh tempered air from theNO PHOTO AVAILABLE mechanical ventilation system. The entire building is mechanically ventilated with a 2-duct supply and return system, within the air handling unit located in the roof top plant room. HVAC system modifications: This case study focus on the actual system analysis, thus no modifications were implemented. Lessons learned: Detail thermal simulation tool can be very helpful to predict HVAC system consumption and consequently avoid some errors in the project or correcting them during an Audit. 10
  11. 11. UKCS 9 – London Case: This case study aimed at assessing the energy performance and its potential for improvement, of a comfort cooling system installed in a 2 storey office block. The conditioned area consists of open plans and cellular office rooms, meeting rooms. Installed HVAC system: The conditioned area has a custom Built AHU. The packaged roof top units are VRV condensers with 3 pipe Heating/Cooling and NO PHOTO AVAILABLE heat-recovery unit, believed to be operating as modular banks of 7 per floor. The ground and first floor ceiling voids contain in total 56 Daikin VRV 3-pipe heat and cooling ceiling cassettes. HVAC system modifications: This case study focus on the actual system analysis, thus no modifications were implemented. Lessons learned: Detail thermal simulation tool can be very helpful to predict HVAC system consumption and consequently avoid some errors in the project or correcting them during an Audit. PCS 5 – Porto Case: This case is about the INESC building located in the campus of Porto’s faculty of engineering. This is a typical 4 stories service building. Installed HVAC system: The HVAC system is centralized and composed by a boiler, a chiller and two ice storage tanks. The air distribution is done by using fan coil units. HVAC system modifications: The main tested alteration consists on the reprogramming of the central control unit in order to provide the use of free cooling whenever possible. Lessons learned: The use of free cooling is estimated to offer an energy saving potential by the order of 28% year.Hospital Buildings ACS 2 – Linz Case: This case concerns with the optimization of the refrigeration plant existent in the central hospital of Linz. Installed HVAC system: The refrigeration plant is equipped with a 6-cilynder 2-stage compressor. The heat rejected can be collected and used for heating water. HVAC system modifications: The modification was basically the replacement of the 6-piston compressor for a 6 screw compressor with 40% more of cooling capacity. Lessons learned: The saving potential was even higher than estimated, achieving 30-35%. ICS 2 – Vercelli Case: This case intents to show the optimization of a hospital AHU that treats the air from a surgery room. Measurements were done and the data collected will be used to assess the system’s efficiency. Installed HVAC system: The actual installed HVAC is a centralized system (with AHU, chiller and water loops). HVAC system modifications: In order to improve the system’s efficiency several solutions were studied, such as the substitution of the chiller, the capability to use free cooling and the heat recovery from the condenser units. Lessons learned: Several economic and energetic analyses were done. The use of two new chillers in partial load instead of three installed ones can achieve savings on the order of 1460 €/yr. Savings associated to a one degree variation in the limit temperature at which the chillers are shut off and free cooling is adopted (23°C vs 22°C) are approximately equal to 50000 kWh/yr (with negligible differences between existing and new chillers), i.e. on the order of 12%.This demonstrates that there is an opportunity for cost effective energy saving measures. 11
  12. 12. ICS 3 – Oderzo Case: This case is about a 3-storey hospital building. Installed HVAC system: 100% external air AHU. This unit has humidifier, fans, HEPA filters, cooling coil and heating coil. HVAC system modifications: In order to improve the system’s efficiency several solutions were studied such as free-cooling with an achieved energy NO PHOTO AVAILABLE reduction of 16% and heat recovery. The average thermal effectiveness of the intermediate-fluid heat recovery system turned out to be on the order of 58% (based on measurements) and for an air-to-air heat exchanger 65%. Lessons learned: This case study has allowed a quantification of the impact of AHU operation on the electrical energy consumption of an all-air AC system for a hospital. It shows as well that some energy saving measures can be implemented with good results.Commercial Building UKCS 4 – Cardiff Case: This case study aimed at assessing the energy performance and its potential for improvement, of a comfort cooling system installed in a small commercial architectural practice operating as part of the Welsh School of Architecture (WSA). Installed HVAC system: DX splits were installed for comfort cooling. TheNO PHOTO AVAILABLE system has roof mounted condensers and wall mounted slim-line cassettes. HVAC system modifications: This case study focus on the actual system analysis, thus no modifications were implemented. Lessons learned: Detail thermal simulation tool can be very helpful to predict HVAC system consumption and consequently avoid some errors in the project or correcting them during an Audit.Other Service Buildings BCS 3 – Liège Case: This case is about a laboratory located in Liege, Belgium. The conditioned floor area is 4000 m2. This building contents a set o offices, meeting rooms, dinning hall and laboratories. Installed HVAC system: The installed HVAC system is composed by Terminal Units such as Fan coils and a AHU that supplies conditioned fresh air using textiles diffusers. The AHU and the Fan coil units are fed by water loops. The hot water is produced by a boiler and the cold water by chillers. HVAC system modifications: This study only indicates retrofit opportunities no modifications were made in the installed system. Lessons learned: Better distribution of the hot water temperature to the actual space heating demand and another mode of sanitary hot water production seems to provide reduce de gas consumption. A recovery heat pump could be used with extracted air as cold source in order to enhance heat recovery from AHU. 12
  13. 13. PCS 1 – Porto:Case: This case is about a computer center existing in the Faculty ofEngineering of Porto University. The rooms in analysis are 4 and are in functionall year to guarantee the functioning of the faculty’s computer network andinternet.Installed HVAC system: the system installed is not centralized. Each room hasindependent cooling units. The units existent are basically DX close control andsingle split units.HVAC system modifications: The proposed modification for this case consistson the substitution of the actual DX units for a centralized system, being thechilled water loop fed by a chiller and the hot water loop fed by a boiler. Oneother fundamental change was the introduction of the possibility for the systemto free cool the spaces given favorable outdoor temperature conditions.Lessons learned: The main achievement was the use of free cooling as wellas the savings due to the increase of the chiller efficiency (EER). Thesemeasures result in a 70 % decrease of the compressors functioning hours andin an overall 30% electric energy reduction.PCS 2 – Porto:Case: This is the case of three auditoriums existent on the Faculty ofengineering. These auditoriums are equipped with an Air-Air type system. Theanalysis done to this rooms was merely acoustic.Installed HVAC system: This air-to-air system is composed by roof-top units(one per room) and heat pumps to provide the heating and cooling energy. Thisunit mixes fresh air with return air. Given favorable conditions, the controlstrategy is prepared to allow free-cooling.HVAC system modifications: The proposed modifications are focused on theventilation system. Some modifications were done in order to reduce the noiselevel inside the rooms. Modifications like the displacement of the mixing box orthe placement of acoustic attenuators were tested.Lessons learned: The acoustic comfort can be achieved with parallelimprovements on the indoor air quality and energy efficiency.PCS 3 – Porto:Case: This case relates to library in the Porto’s faculty of engineering. This is an8 stories building that works from Monday to Friday. This case study intents toassess and resolve a comfort problem reported by the library users.Installed HVAC system: the system installed is centralized. There’s a boiler anda chiller on the roof that feed the chilled and hot water loops respectively. Theair loop is handled by an air handling unit.HVAC system modifications: The proposed modification for this case consistson the use of CO2 as the fresh air control indicator, the change of the lighting 2density to 8 W/m , use of vertical and horizontal shading devices on the southfacing windows and the alteration of the set-point temperatures.Lessons learned: All these measures resulted in energy savings. By combiningsome of these actions the building can archive 43 % energy reduction.PCS-4 – Porto:Case: These case intents to study the influence of the AHU filters conditions onthe ventilation energy consumption in a laboratory room located within FEUP.Installed HVAC system: The studied AHU is composed by two fans, electricresistances for heating and a DX system for cooling. The filters tested wereplaced on the fresh air inlet side.HVAC system modifications: The modification done was basically tosubstitute a dirty filter by a new one, and monitor the fan motor energyconsumption.Lessons learned: The lack of the filters maintenance reduces the indoor airquality, and leads to energy waste by the fan motors. 13
  14. 14. ACS 1 – SalzburgCase: This case relates the energy consumption changes in a new archivebuilding along with the years and with several interventions in the system inorder to decrease the energy consumption.Installed HVAC system: There’s no pertinent information about the coolingsystem.HVAC system modifications: The modifications done were mainly on thesystem control and management.Lessons learned: A good management of the system can, without furtherequipment modification, achieve much higher energy efficiency. In this caseenergy savings achieved 70%.ICS 1 – TurinCase: This case is about an office building in Turim that renewed the HVACsystem. However this new system seemed to be inadequate. Thermalsimulation tools were used to assess other HVAC equipments in terms ofenergy consumption and thermal comfort.Installed HVAC system: The HVAC system installed is composed byembedded floor radiant panels and AHU’s.HVAC system modifications: The most important simulated modification werebasically the use of AHU with fan-coil units instead of radiant floor and thesubstitution of the heating oil burner for a natural gas boiler connect the systemto the gas network.Lessons learned: The results obtained using simulation show that a 25% ofthe HVAC energy saving can be spared.ICS 4 – BologneCase: This case study was aimed at analyzing the performance of a water-to-water reversible heat pump installed in a research center located in Apenninemountain.Installed HVAC system: The AC is an air-and-water system type (primary airand two-pope fan coils). Hot and chilled water is produced with a water-to-waterreversible heat pump, using treated lake water that feeds the AHU and FCU’s.HVAC system modifications: This study focus on the actual system analysis,thus no modifications were implemented.Lessons learned: The presence of a BEMS makes it possible to monitor andrecord the main system operational parameters. The seasonal average COP forthe installed system is equal to 3.9 and a good correlation between daily coolingenergy and outdoor dry-bulb air temperature was identified. 14
  15. 15. WELL DOCUMENTED CASE STUDIESTwenty Six case studies were analyzed. Among these, 6 were considered to be the welldocument case studies. This selection was carefully made so that we could extrapolateAC systems in terms of typology of the buildings allover Europe. Below are the casestudies considered to be the best document examples and their location.CICA - Informatics Center • FEUP, PortoThe building has three floors and the ground floor is the centre of informatics resources.The function of this building is mainly to ensure and make available all the informaticsservices for the FEUP community and to uphold its innovation and use.The cooling power installed in these spaces is not enough to remove the total load thatoccurs inside the building, which causes a high indoor air temperature leading to harmfulsituations, causing damages and reducing the performance of the informatics hardware.The original HVAC is a non centralized VRF system where the local cooling units areceiling splits and close control units with an outdoor condenser unit.Problems • Actual HVAC system is not adjusted to the demand • The internal loads are higher than the installed HVAC system, causing the damage and reducing of the performance of the informatics hardware. 15
  16. 16. • In summer the indoor comfort is more challengingSolutions – Major ModificationsThe solution proposed is, in energetic and environmental field, the most adjusted since itis a centralized system and has a higher efficiency. This solution also allows the powerincrease without major costs.The considered HVAC system can be defined as an air/water system. It will becomposed by a cold-water central producer (chiller), located in the building covering, andby a cold water distribution net with two pipes, for supply and return. This circuit willsupply the existing cooling coils in the independent Close Control units. These units arelocated inside the acclimatized spaces or, guarantee the indoor air quality. This systemwill also include the possibility of free-cool the spaces, given the adequate exterior airconditions.The following equipments form the proposed system: - Chiller with scroll compressor with 100 kW of cooling capacity; - Four Close Control units supplied with cold water which integrates system of humidification and electric resistance for heating; - Ventilation, piping and control systemAccomplished improvements:The energetic and power consumptions of the existing Close Control units in the 4zones, obtained through dynamic simulation, are 128 MWhe/year. It should be noted thatthis analyses considers the consumption of the compressor, the ventilation, the reheatcoils and humidification. Using once again the dynamic simulation, the obtained energyconsumption for the proposed solution is 87 MWhe/year.The new system with free-cooling and electrical reheat is much more effective than theothers, except the system which uses hot water for reheat. However this system wouldrequire a boiler so the system would consequently become more complex andexpensive. 16
  17. 17. As it is verified the energy earnings, of the floor -1, with the substitution of the currentsystem for the proposed, they are of 41 MWh. This value corresponds to 2.870,00 Eurosa year of economic won (the price of the electric energy was esteemed in 0,070 €/kWh).The proposed solution presents certain advantages when compared with the existingsystem:The cooling capacity can be increased with the connection of one or more chillers.According to the type of equipment, it is possible to connect them and optimize itsfunctioning. All these systems allow a centralized management and partial loadsaccording to the thermal needs. The circulation fluid is water, which do not present anyrestriction or danger as refrigerant fluids. When necessary, the upgrade of the indoorpower is simple and easy to implement. The terminal units could be independent of thecold unit production, in what refers to the mark, model or type. The lifetime of thisequipment is always higher then that of splits units. 17
  18. 18. Office Building • MariborThe energy system of an office business building is presented, where at minimal energyconsumption, optimal working conditions are achieved. The investment costs are in thesame range as the investment costs for a traditional building. Building is heated with acombined heat pump (water – water), which prepares heating and cooling medium forthe whole building. Heating source is ground water from a spring. Heat and coolingenergy are partly transmitted into the object by thermal activation of concreteconstruction and by supplied air of ventilation units. Local regulation of temperature ispossible through local heating coils, built in special displacement air distributors. Wholespace is ventilated with high energy efficient ventilation / air conditioning units withenergy recovery more than 90%.ProblemsThere are no problems reported for this building. In fact, this case study aims to reportthat is possible to combine technology, comfort and reasonable expenses.Accomplishments:As said, the building was designed to achieve high energy performance thus reducingthe energy consumption. This global goal was approached by several sides: the buildingenvelope [sun exposure and wall and glazing materials] and the HVAC systemsinstalled.The glazing is a two – layer glass type, argon filled. It is combined with high qualityaluminium profiles, with interrupted thermal bridges, thermal insulated. There is also a lotof innovative details of interruption of thermal bridges at connections glazing to concreteconstructions.Performance of the cooling system is optimized for lowest possible energy consumption.Big amount of sensible heat is cooled with thermal activation of concrete construction itgoes on large surface area, which means high cooling medium temperature – lowenergy consumption. 18
  19. 19. The basic heat source is underground water. In winter it has a temperature around 10-13°C,o on the other side, we have thermal activated concrete construction with largeheat areas, which means extremely low temperature heat medium of 25 – 26ºC, whichassures that the heat pump works with a excellent coefficient of performance (COP) 5-6.Comfortable working conditions for employees are also achieved with a permanentsupply of fresh air into the rooms with three air-changes per hour. Ventilation with 100%of fresh outside air wouldn’t be rational if it wasn’t done with ventilation and airconditioning units that have heat recovery of 92 % and humidity recovery of 87% at thelowest outside temperatures. In summer the air conditioning units also dehumidify theoutside - inlet air when it is necessary, which assures comfortable working conditionseven at extreme conditions of the outside air.All these design characteristics led to a real high energy performance. The resultsobtained after 24 month of operation revealed that the building is indeed efficient. 19
  20. 20. Office Building • BrusselsDescription:This is a medium size office building (28 000 m2) erected in centre of Brussels at end ofthe sixties. This building is constituted by open plan offices and (a few) meeting rooms.The whole building has an air conditioned system with the exception of the car park.The original HVAC system is four pipe induction units in all offices and CAV/VAVsystems in other zones.Classical heating and cooling plant, with fuel oil boilers and vapor compressions chillerswith cooling towers.Control Strategy:The building is equipped with a classical BEMS with two levels: a set of local controlunits and a PC for supervisory management.The comfort must be satisfied from 7 am to 8:30 pm, five days per week.The BEMS is imposing an earlier re-start, according to weather conditions.There are also some special requirements for the (prestigious) ground floor: the airconditioning is required there all along the year in order to protect the (exotic wood)decoration!Indoor air temperatures are measured at three different locations of each floor (exceptfor floors 5 and 6). The average of all these temperatures is used by the BEMS in orderto fix the primary air temperature.The primary air is only supplied during pre-heating and occupancy time.Outside that time, if the weather is very cold, the induction units are still used in freeconvection mode, by supplying hot water to the heating coils. 20
  21. 21. Accomplished improvements and Retrofit Opportunities:An attempt of free chilling was done sometime ago, by adding a water-to-water heatexchanger between the condenser and the evaporator circuits (in parallel to the chillers).For reasons still to be investigated, this experience failed and the system wasdismantled.The AHU’s were partially renovated and the replacement of all induction units andthermostatic valves is now projected.The replacement of existing induction units by more efficient devices (other inductionunits or fan coils), if fitting in the small space available, should make possible to run thesystem with higher chilled water temperature and therefore better COP.The environmental control should also be made more accurate.More indoor temperature sensors will be installed in the occupancy zone for bettercontrol of set-points.But much other retrofit potential should be considered:- Variable rotation speed for pumps and fans- Optimal control of chilled water temperature- Energy recovery loops between supply and exhaust air circuits- Air recirculation- Optimal control of cooling towers- Free chilling (again!)- Chiller condensers heat recovery- Use of chillers in heat pump mode (when no more used for cooling) 21
  22. 22. Archive Building • SalzburgDescription:This case study relates to a building built in 2003/04. This building has it the energyconsumption measured online by an energy monitoring system. In the first months highenergy consumption was registered. It was thought that this high energy consumptionwas due to the fact that the building had been recently constructed.Optimization measures were taken in order to reduce the energy consumption. It waspossible to reduce the consumption by about 40%. During August and September theregulation and cooling system companies cooperated in order to increase energyefficiency in the system. From this cooperation resulted a 60% reduction in the energyconsumption. The year of 2005 brought the evidence that is possible to reduce theconsumption by more than 70%Problems:The main problem detected in this building was the high energy consumption. Thesystems were not functioning properly. It was realised that the range for the air was toosmall. When the room temperature was too high, the climate cabin started to cool theroom. The result was that the room became too colt and than the heating system had tostart heating the room. The system was continuously cycling between on and of mode.Accomplishments:After the detection of the problem several modifications were made. The combined workof both regulation systems and cooling system companies resulted in an energyconsumption decrease of about 70% 22
  23. 23. Cultural Building • TurinDescription:The building of the culture department is situated in the historic centre of Turin has fivefloors, building houses administration offices of the City Council and a library. The oldbuilding was renovated in 1996 when a new HVAC was installed, but over the years thissystem has been seen to be inefficient and not adequate for the building’s needs.The actual HVAC system is constituted by: primary air plant, embedded floor radiantpanels supplied with warm water in winter and cold in the summer.Problems:The HVAC system is formed by embedded floor radiant panels that cool theenvironment, without relative humidity control. The humidity is controlled by differentAHU’s in the building. In winter this system works well, in fact the air is heated andhumidified by the AHU and the embedded floor radiant panels function correctly. Insummer, however, the temperature of the water circulating in the panels cannot gounder 18°C or there are problems of condensation and mildew and the single primary airplant cannot maintain the correct environmental conditions.The distribution of air produced by the various AHU, located on each floor of building,passes through rectangular or circular channels with run in the corridors. In summer, thedistribution of air in areas distant from the AHU’s is not enough to guaranteemaintenance of optimal temperature and air control conditions, in fact the people thatwork inside these offices experience some problems. 23
  24. 24. Proposed Solutions:Change the embedded floor radiant panels to fan-coils. The new HVAC system can stillbe defined as air/water system but, it will be composed of AHU’s for ventilation, and cold– hot water distribution for the fan-coils.Use a suitable BMS, the system is already predisposed with a specific control consoleand suitable software.Strengthen the fan of the various AHU’s because the existing fans are insufficient toforce air to the offices distant from the AHUIntensify the maintenance of the fittings that is currently performed by an external firmand the inspection of the components by the administration.Use electricity meters to download electric consumption on an hourly and daily basis, inorder to collect further information for an effective audit of the building.Change the burner that is currently installed (heating oil) to a methane model andconnect the system to the gas distribution network. 24
  25. 25. Archway House – Office Building • CardiffDescriptionThis building, located in Cardiff-Wales, is an office building with the respective officefunctioning profile. This case studied intents to assess whether or not thermal simulationtools can provide an interesting and reliable tool in energy auditing. The building herepresented is equipped with VRF multi/split systems with the capability to use free/coolingwhenever possible.Electrical energy consumption data was collected for June, July ad August. The aim is tosimulate the building in a thermal simulation tool and then compared the simulatedvalues with the real ones. To see if values obtained by simulation are reliable, and thusThe software used was the EnergyPlus and the weather data used was real data for thesame period as the electric measurements.The heating was not assessed; the aim is only to assess the cooling performance.Only one of the spaces, AC_zone, has a cooling system. It is intended an internaltemperature of 24 ºC, during the labor hours. There is a 2-pipe cooling Multi-split DXsystem with the following known characteristics:Rated Power Consumption: 35.4 kWTotal Cooling Capacity: 75 kWThere is also a free-cooling system, on whenever the outdoor temperature is lower than17.5 ºC. This system allows a great energy saving, especially in locations with lowsummer temperatures, as it is the case of Cardiff.Solutions encountered using simulation software: 25
  26. 26. From the breakdown analysis it can be concluded that the following ECOs could be usedto help reduce the cooling energy demand in the building: - ECO E4.5 – Replace electrical equipment with Energy Star or low consumption types. - ECO E4.9 – Move equipments (copiers, printers, etc.) to non conditioned zones. Electrical equipment loads are the highest loads among the internal gains in this case, therefore any possibility to reduce the amount of energy they use and release should be considered. Most of the copiers and printers, etc in this case are in the conditioned zone, relocation to non conditioned areas could also be considered to reduce the cooling loads. - ECO E4.7 – Modify lighting switches according to daylight contribution to different areas. - ECO E4.8 – Introduce daylight/occupation sensors to operate lighting switches. Electrical lighting seems to be on all the time according to the survey and its contribution to the cooling demand is considerable. - ECO E2.1 – Generate possibility to open/close windows and doors to match climate. Ventilation should be used as much as possible as a free cooling source as the outside air temperature tends to be lower that the inside air temperature. - ECO E1.1 – Install window film or tinted glass. - ECO E1.3 – Operate shutters, blinds, shades, screens or drapes. Solar control should be used to reduce the cooling loads, even though it is not the highest contributor to it. - ECO O2.2 - Shut off A/C equipments when not needed. The ancillary equipment to the A/C system is apparently consuming 3kW even when then system is providing no cooling. The relatively short period of time that this system provides cooling means that this load becomes a very significant component of the overall energy use, and reduces the overall COP dramatically. 26
  27. 27. RESULTS AND ENERGY POTENCIAL IMPROVESGeneral energy ImprovesIn general overview, the observed potential energy savings in different real examplescan be subdivided in a few audit strategies, such as: 1. management system control optimization 2. efficiency control of the equipment energy consumptions 3. lighting efficiency control 4. new strategies of recovery energy 5. free-cooling strategy implementation 6. simply chiller equipment replaceTo achieve a good Potential Energy savings strategy the building’s owner (or auditor)must to know well the energy utilization such as: • running hours of AC and the length of pre-cool period; • internal comfort conditions, ie temperature, humidity, lighting levels; • localization of the unnecessary AC and lighting, I e unoccupied zones; • chillers/pumps schedules and settings; • specific equipment energy consuming • lighting energy consuming • the areas of high energy consumptionsIn Europe, and in particular countries, it is possible to have an idea of the energyutilization for the office building sector. Therefore, the auditor know, in the first approach,how is the potential energy saving that can achieve if applied different strategies thatpresented above. The figure shows the average energy end-user breakdown typical forthe European office building sector. HVAC 27% Lights 33% HVAC 25% - 30% LIGHT 30% - 45% Equip 25% - 40% Average Energy end-user breakdown for EU office building Equipments 40%Energy end-user breakdown from Belgium CS1 27
  28. 28. Some audit cases had energy improvements only with a new lighting strategy control, forexample the PCS-31 the reduction the light to 8 W/m2 it had have double effect on theenergy consumption, first in direct electricity consumption and second in the reduction ofinternal loads, ie peak cooling power. At the end, with global strategy control for the ACsystem, the global system achieves 43% of energy reduction. Of course it is not only thelighting effect but all control strategy.Good control and management of the system in same cases can reaches a high saveenergy. This was happen in the ACS-12 case study when the total save energy it was upto 70%. This is an excellent example but the average control management has lessenergy efficiency indeed.The use of free potential energy (free-cooling) is used in some cases with excellentresults in same cases the energy profits can achieve from 30% to 60% reduction of thetotal energy consumption. This solution is well dependent fro the weather conditions andthe countries with cool climates are more suitable for this kind of solution.Equipment ReplacementThere are a significant number of examples, in AdiBAC, based in replacement coolequipment, ie change the old chiller by a new one with high efficiency. The CS showssome examples were the energy saves can be up to 35% of total energy (ACS-2)4, andother when the energy saves reach 56% of the energy used for the cooling system(FRCS-1)3.It is quite possible to make an idea how energy we can save if we make chillerequipment replacement, in average point of view. Based upon the EER evolution in thelast ten years, that means ± 30% increase efficiency on average (EECCAC), therefore itis possible to forecast the potential energy save for the next days in the AC systems.The "cases" in the data base are real installations which are described under the formatthat the various existing reference frames request in order to make them comparable.For part of the existing case studies it will be necessary to supplement informationavailable by complementary measurements and / or by calculations so that all themethods become applicable. Besides their use in further work packages, the casestudies in the data base will allow for the first time to estimate on a statistical basis themagnitude of the gains possible on European A/C installations.1 AuditAC Case Studies Brochure: Case studies: Portuguese, n32 Auditac Case Studies Brochure: Case studies : Austrian, nº 1and nº23 Auditac Case Studies Brochure: Case Studies: French , nº1 28
  29. 29. DETAILED INFORMATION FOR AC CASE STUDIESAustrian Case Study 1ACS1City Archive Georg Benke Austrian Energy Agency – Austria Date: December 2006 There’s no pertinent information about the cooling systemIntroductionThe new city archive was built in 2003/2004 and started to “operate” in March 2004. Asall buildings owned by the city of Salzburg, the energy consumption was measuredonline by an energy monitoring system (EMS), measuring the energy and waterconsumption in 15 minutes intervals. In the first months (until End of July) it was thought,that the high energy consumption was due to the present situation, the building was newand the materials were just brought in, causing the constant opening of the doors.In the last week of July 2004 the installers of the ventilation systems were order tooptimize the system. It was possible to reduce the energy consumption by about 40 %.During August and September two teams (one for the regulation system and one for thecooling system) tried to optimize the system but only achieved the expected result, a 60% reduction at the beginning of November.The year 2005 brought the evidence that it was possible to reduce the consumption bymore than 70 %.Building DescriptionThe Building was built in the year 2003-2004 to be the official Archive for all theinformation, documents and papers of the City of Salzburg. It is situated in the north –west of the Kapuzinerberg hill and is usually in the shadow of this small hill. (See mapand also pictures below). About 20 people work in the building. The building is heated bythe district heating system.The working places are situated in front of the four floors high storage area 29
  30. 30. Design DetailsThe regulation system of the company controls 9 different storage areas and providesthis information to the air climate cabin. If the air is outside a certain range (f.e. 18°C / 50% Humidity) the air climate cabin or the heating system starts to operated.It was acknowledged that the range for the air was too small. When the roomtemperature was too high, the climate cabin started to cool the room. As a result theroom became too cold and the heating system had to start heating the room. Thesystem was continuously cycling between on and off modeBuilding Energy PerformanceThe energy consumption (electricity) for the whole building: 2004 2005 kWh kWhJanuary - 7.282 Energy Comsumption (KWh) 25February - 5.125March 13.270 4.110 20April 17.805 4.009 15 2004May 20.129 4.233 2005 10June 18.014 4.684 5July 23.522 4.723August 13.360 4.859 0 ce e r M y Fe a ry ne r A ly ch ril ve r O er pt s tSeptember 10.008 3.161 ay be e r De mb Ju ua Ap Se ugu ob b Ju ar M nu m em br ct JaOctober 10.342 4.773 NoNovember 10.008 3.197December 5.871 - 142.329 50.156Cooling and Ventilation PerformanceThere is a Central Ventilation system – situated on the roof which brings the air to thenine Climate storage areas, each have a different temperature (between 14-21°C). Theheating / cooling is done decentralise for each area, which have also 9 heat exchangers.The humidity should be 50% (45% - 55%).There is no CO2 sensor in the storage area.Summary It was not so easy to solve the problem previously described because in the beginningthe companies did not try to solve the problem together. Each company tried to find asolution on his own.When they start to cooperate, they realized that the range for the quality of the air wastoo small. The range was made larger an the energy consumption could be reduced by70 %. 30
  31. 31. Austrian Case Study 2ACS2Hospital Georg Benke Austrian Energy Agency – Austria Date: December 2006 The refrigeration plant is equipped with a 6-cilynder 2-stage compressor. The heat rejected can be collected and used for heating water.IntroductionThis case study is aimed at optimizing the operation of the refrigerating equipmentpresent in the General Hospital of Linz, a general hospital with 1000 beds, serving188,968 inhabitants. There are 6 Piston compressor engine(Kolbenkompressormaschinen) in two station (three per station) from the year 1985 and1987, Refrigerant R22) which were on their cooling limit (2500 KW). It was made aforecast for the year 2008, and as a result of this study the cooling needs would reachthe 3600 kW. A decision was made in order to replace all 6 engines with 6 Screwcompressors (Schraubenkompressoren), which have up to 40 % more cooling capacityand need less energy. Building Data General Hospital Linz / Upper-Austria 1000 beds Space Activity 45.000 ambulant patients (year) 28.000 operations per year Nr. of employees 2000Design DetailsInitial SituationThere are 6 Piston compressor engine (Kolbenkompressormaschinen) in two station(three per station) from the year 1985 and 1987, Refrigerant R22) which were on theircooling limit (2500 KW).The system was designed in the way, that the waste heat of the compressor could beused to heat hot water or the Reheating register of the ventilation system. But in thesituation, when the highest amount of heat was available, nobody need it. Duringsummer, when the temperature outside was higher than 30 °C, the inlet temperaturewas 48°C and the outlet temperature was 54°C in this case the COP was less than 2,5.Implemented Situation 31
  32. 32. The 6 piston compressors were replaced by 6 Screw compressors(Schraubenkompressoren), which have up to 40 % more cooling capacity and need lessenergy.Control StrategyThere were also smaller changes within the control system of the cooling centre. Therewas no change in the kind of cooling consumption all over the hospital. Date of the new screw compressor: Type: 30HXC190-PH3 Cooling capacity: 622 kW Electricity consumption: 130 kW Evaporator capacity: 622 kW COP: 4, 78 Performance levels: 6 Minimum level: 21 % Refrigerant: R134aWithin the control systems of the cooling centre the following changes are possible:An own program make a calculation about the energy consumption (Cooling, heating)within the next 24 h. Based on these results, it is possible the change the coolingdemand in time.If the outside temperature is less than 18°C and the enthalpie about 45 kJ, it is possibleto raise the Cooler outlet temperature to 7 or 8 °C. (Otherwise it is 6°C). This goes handin hand with the weather forecast.To optimize the efficiency of the cooling engine, they try to operate always with 100 % or50% per engine.Cooling PerformanceCharacteristic data from the screw compressor Performace Condensor inlet Cooling Electric COP level temperature Capacity Capacity % °C kW KW 100 31°C 622 130 4,78 86 31°C 532 123 4,33 71 31°C 436 109 4,00 50 31°C 316 67 4,72 36 31°C 218 54 4,04 21 31°C 155 47 3,30To optimize the production of cool on a hot summer day, an extra Heat exchanger unitwas fixed on the roof. With this heat exchange unit it is possible to reduce the inlettemperature from 48°C to 38 – 40°C. During winter they will use free cooling, when theoutside temperature is less than 8°C. The heat exchanger on the roof should be enoughthe offer a cooling demand of 150 to 200 kW (reduction).SummaryThe first part of the renovation was done in May 2003. Concerning to calculation it wasexpected that the electricity consumption will be reduced by about 20 to 30 %. Themaximum power load will be reduced by about 180 kW and the energy saving is up to500.000 kWh. First result showed that there is a saving even between 30 to 35% - in thishappened in the hot summer 2002. 32
  33. 33. Belgium Case Study 1BCS1Office Building Corinne ROGIEST-LEJEUNE Philippe ANDRE University of Liège - Belgium Date: December 2006 Heating – three gas boilers with variable flow to feed radiators and AHU’s. Cooling – two chillers with reciprocating compressors and air condensers with variable flow to feed AHU’s and fan-coils.IntroductionThe building is located in the center of the town of Namur where it must be integrated inthe city landscape. The building has been defined in modules in order to take intoaccount the slope of the street.The commissioning and the management of the HVAC system have been monitored bythe University of Liège.Building descriptionProject Data Location: Namur (Belguim). Altitude: 90 m Year of construction: 1997/1999 Costs in €: 52 500 000 Number of working spaces: 884 Degree days: (15/15) 2240 Kd Heated floor area: 31440m2 Heated space: 105000 m3 Inst. heating capacity: 3150 kW Inst. cooling capacity: 1825 kWBrief description of the type of building in study: Big size (68000 m² with 32000 m² offices) office building. Modular architecture: 11 blocs. Most of the useful area of the building consists in offices. 33
  34. 34. Figure 2: sketch of the building at design stageDescription of the building layout: Two big (300 meters long) rectangular buildings (South wing and North wing) connected together by an atrium except for the central bloc that is the entrancehall. 3 levels under ground (parking and road tunnel). 3 levels in the North wing and 5 levels in the South wing, for offices. The atrium has no level and is covered by glass. Figure 3: lateral facades of the building Figure 4 : building sectionDesign ConceptBuilding EnvelopeDetailed description of the building envelope:Per office: South: 0.08 m² heavy opaque concrete structure 3.02 m² triple glazing 0.76 m² wooden frame North: 7.35 m² heavy opaque concrete structure 5.21 m² double glazing 1.30 m² wooden frame Atrium North and South: 4.87 m² heavy opaque concrete structure 1.76 m² insulating metallic panel 5.78 m² double glazing 1.45 m² wooden framePhysical properties of the walls, slabs and roofs layers:external North wall (ventilated): natural stone +insulation (polystyrene) 34
  35. 35. + reinforced concrete U=0.47 W/m²Koffice floor: heavy reinforced concrete +light concrete +linoleum U= 1.07 W/m²Koffice ceiling: linoleum +light concrete +heavy reinforced concrete U= 1.07 W/m²Kinternal wall: plaster +acoustic insulation (rock wool)+plaster U= 0.35 W/m²Kcorridor ceiling: paving (gres)+light concrete+reinforced concrete U= 1.89 W/m²Kcorridor floor: reinforced concrete +light concrete +paving (gres) U = 1.89 W/m²Katrium wall: natural stone (pierre bleue)+ air+reinforced concrete U= 1.80 W/m²Kexternal wall South: crepi +insulation (polystyrene)+reinforced concrete U= 0.43 W/m²Ksimple glazing (to interior street): U=3.88 W/m²Kdouble gazing (North):glazing + air +glazing U=2.81 W/m²Kexternal wooden frame: U=2.86 W/m²Kinternal wooden frame: U=2.45 W/m²Katrium frame: U=2.86 W/m²Katrium glazing: glazing +air +glazing U=2.83 W/m²KSolar and Overheating ProtectionPassive technology: Atrium between the two buildings to increase solar gains duringwinter.In North façade, windows are large because of no noise from the road. In South façade,windows are smaller to limit solar gains and noise from the station. There is an externalmetallic structure to shade the top of each level in the South facade. Figure 6: view of solar protectionsDesign DetailsGlobal description of HVAC system type:Central heating production by 3 natural gas boilers (operating in cascade) with hot waterloop with variable flow (to feed radiator circuit and AHU).Central cooling production by 2 chillers (reciprocating compressors with air condensers)with cool water loop with variable flow (to feed AHU and fan-coils).Heating and cooling power is distributed through huge collectors feeding the substations.There are 5 groups (substation) for each set of two architectural modules.Substations feed terminal units in offices, meeting rooms and atrium.The terminal units are VAV boxes (cooling and ventilation), fan-coils (heating andcooling in the meeting rooms) or radiators (only in the offices). Thermostatic valves orVAV terminals provide local control.Terminal units 35
  36. 36. In the offices: Figure 7: view of the terminal unitsAbout 1 500 terminal units with VAV (Variable air volume) installed in the ceiling of all offices. These ventilation boxes are used for both air renewal and cooling. Thetemperature set point is selected by the occupants. Radiators with thermostatic valves installed in each office. The supply watertemperature in to the radiators is regulated by a three-way valve in function of theambient temperatureIn the atrium:Terminal units with CAVIn the meeting rooms:Some rooms (meeting rooms) are provided with fan-coils which supply air, pre-heated at20°C.Air handling unitsThere are 5 AHUs (substation) for each set of two architectural modules (example G-H): - “S1” for offices in South wing - “S2” for the atrium, South side - “N1” for offices in North wing - “N2” for atrium, North side - “N3” for meeting rooms (located between the 2 modules in the North side). Figure 8: organization of the AHUs distribution 36
  37. 37. For group S1 and N1, the AHU feeds the offices with fresh air at fixed air volume (4300m³/h) and re-circulated air with variable air flow (8600 to 18900 m³/h).For group S2 and N2, a fixed (constant air volume) part of the air extracted from theoffices (3400 m³/h) is injected in the atrium after cooling and-or heating in the AHU.Difference between fresh air and air injected in the atrium air is extracted through thecorridors to the sanitary by extraction fans. M.E.T. Namur P Ventilation Rue Intérieure Bloc p Atrium t t h t Cde Etat CAV Cde Dis. Etat Dis. p VAV p p t h Offices Fresh Cde Cde p Etat Cde Etat Air Dis. Dis. Figure 9: detailed view of a typical Air Handling UnitGS1 is constituted from: GS2 is constituted from: Register Register Filter Filter Heating coil (68 kW) Heating coil (16 kW) Cooling coil (123 kW) Cooling coil (22 kW) Humidification battery Fan with constant flow (3400m³/h) Fan with variable flow (8600 - 18900 m³/h)GN1 is constituted from: GN2 is constituted from: Register Register Filter Filter Heating coil (54 kW) Heating coil (18 kW) Cooling coil (83 kW) Cooling coil (23 kW) Humidification battery Fan with constant flow (3400 m³/h) Fan with variable flow (8600 - 18900 m³/h)GN3 is constituted from: Register Filter Heating coil (17 kW) Fan with constant flow (1600 m³/h)Cooling plantThe cooling plant is composed of two chillers, which have nominal capacity of 869.5kWand 956.5kW respectively.Each chiller is composed of: 3 or 4 screw compressors 1 water heated evaporator 2 air-cooled condensers 2 electronic expansion valves (one per condenser) 3 or 4 oil separators (one per compressor) 37
  38. 38. 3 or 4 oil cooler (one per compressor) 3 or 4 filters (one per compressor)Both chillers use two independent refrigerant circuits, which are connected to the same evaporatorFigure 11: scheme of the chiller circuits Figure 12: distribution of cold waterChiller 1 is located in the west side of the building and chiller 2 at the opposite in theEast side of the building.Chiller 1 has 4 twin screws, direct drive compressors, 2 for each refrigerant circuit; chiller2 has 3 screw compressors, 2 for the first circuit and one for the other.The cold water circuit is divided in “primary” and “secondary” water networks.Control StrategyGlobal controlElectricity and HVAC are controlled separately.Supervision software is used to - adapt the hourly settings - manage automatic cut off of electrical circuits - visualize process control - manage the alarms - record electrical consumptionsThe management of HVAC system is based on one central unit and several controlstations. central unit: - supervision of all of the HVAC system in DCC - collection information from collect units, analyze - optimize HVAC performance to reduce energetic costs - facilitate maintenance control station: - function modulesThe control system is different for heating and for cooling and, for both cases, shows ahierarchical nature, starting from the control of the rooms, then considering control of thesecondary units (HVAC) and ending with control of the primary plants (boilers andchillers).Specific control systems:Boilers: - set point temperature in relation with external temperature - cascade operation activated by temperature sensor on in and out water 38

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