Par Hill Research Reducing air pllutin frm yur building - a series f manuals fr peratrs, designers & develpers Manual A - Minimising air pllutin during building use Factsheet A5 - Best Practice in building cntrls Janne Arbn & Iarla Kilbane-Dawe
Par Hill Research Minimising air pllutin during building use Factsheet A5 Best Practice In Building Cntrls SOME CONVENTIONS USED IN THIS DOCUMENT Key infrmatin is highlighted in an range bx like this text. 2013 Par Hill Research Ltd. Althugh every effrt has been made t ensure the accuracy f the infrmatin herein, the authrs and publisher can accept n liability fr lss, damage r injury caused by errrs r missins in the infrmatin given in this dcument. The cntent may be distributed freely withut the permissin f the cpyright hlder in electrnic r ther frmat, s lng as the surce and cpyright are acknwledged and n charge is made fr the dcument. Examples and Case Studies These are shwn inside a light blue bx. External Resurces and Clickable links t websites are shwn like this are shwn in blue bld typeface. ww.parhillresearch.cm
Par Hill Research Ltd, Science, Envirnment & Plicy Research A5 Best Practice Fr Heating Cntrl A5.1 INTRODUCTION If yu have an apprpriate system, yu need t ensure it perates at the highest level f efficiency pssible. This requires the system t be cntrlled well, s that it nly perates as and when required; and that it is practively maintained t achieve its designed level f efficiency. Even well designed heating systems can perfrm badly if the cntrls are inadequate r incrrectly installed. As a general rule, clearly it is best nt install unnecessarily cmplex cntrl systems. Hwever, mre cntrl cmplex systems give the greatest ptential fr energy savings prvided they are crrectly applied and maintained. Befre deciding n the apprpriate level f cmplexity it is wrth cnsidering the building size and the staff available t mange the system The size and cmplexity f the building. Fr small individual buildings r thse with a unifrm pattern f ccupancy, pre-set r self-adaptive cntrls with an verride ptin fr ut-f-hurs wrking shuld prvide an apprpriate level f cmfrt and energy savings ver a prly cntrlled system. Bigger buildings with varied requirements will usually benefit frm mre cmplex cntrl systems. The 3 Glden Rles f Heating Cntrl Use plant ONLY when necessary D nt heat & cl simultaneusly - It is essential t ensure that cntrls d nt interfere r cnflict with each ther. Prvide flexibility Gd practice cntrl systems fr under 50kW Optimisatin & zned time-switches Weather cmpensatin & zne cntrls Biler interlck Building Management System Gd practice cntrl systems fr ver 50kW Optimisatin & zned time-switches Zned weather cmpensatin & zne cntrls Biler interlck & minimise standing lsses Building Management System Staff available t manage the system A cmplex cntrl system needs suitably trained peple with the time available t manage it and use the data prduced. There must be staff resurce t ensure that cntrls are calibrated crrectly, tested and wrking well, as cntrls will nt cntinue t make savings n their wn. If n ne is available, it is unlikely that the ptential savings f the cntrl system will be achieved. This is particularly true when perating a BMS system effectively Heating system cntrls cmprise all three f biler cntrls, time cntrls and temperature cntrls. 39 - Reducing air pllutin frm yur building
Par Hill Research Ltd, Envirnment, Plicy & Innvatin A5.2 Biler cntrls The principal functin f mst biler cntrls is t maintain the desired temperature f water that flws frm the biler. At the mst basic level, these cntrls simply turn the system n and ff r prvide a high r lw setting, burt have varying levels f cmplexity. Burner cntrls Burner cntrls manage the fuel-t-air rati which is critical t the efficient peratin f the biler. The fuel-t-air rati is nrmally set n the burner cntrls and will be based n the biler manufacturer s recmmendatins. Prper cntrl f this rati will ensure that the biler is as efficient as pssible. This rati shuld be measured as part f rutine servicing and where necessary remedial actins taken, such as upgrade f the burner t newer, energy efficient versins Older bilers simply have an n-ff burner. An imprvement t the abve is high-lw cntrl, where the burner has the ptin f ging t a lw firing rate, typically 40% f full capacity. This imprves biler efficiency under partlad cnditins. A further imprvement is a mdulating cntrl. With this type f cntrl, the fuel and air supplies are regulated t exactly match the required heat demand. This ensures gd efficiency acrss the whle heat utput range f bilers. Fr larger bilers, a stack gas xygen analyzer can be installed t cntinuusly mnitr excess air and adjust the biler fuel-t-air rati fr ptimum efficiency. Retrfitting f burner cntrls is best suited fr lder, cnventinal bilers with large, variable heat lads. demand fire, and that these bilers are used at their ptimum efficiency lad. Sequence cntrllers can als ensure that the rder in which the bilers fire can be rtated t minimise maintenance csts. Nte that where there are bth cndensing and standard bilers installed, the cndensing biler shuld always take the lead. Biler inhibit/interlck cntrls which prevent unnecessary firing Bilers can cntinue t fire even when there is n demand fr heat (called drycycling) and s all the heat energy is lst t the flue. Simple bservatin and listening when a building is at required temperature can ften tell yu if drycycling is ccurring. Linking the biler cntrls with the heating system cntrls (such as rm thermstats) via a biler interlck will ensure that the biler des nt perate when there is n heat demand and will prevent drycycling. The best ptin will be determined by the size f the system and lcatin f the biler and cntrls. Interlck cntrl is apprpriate fr all types f biler. Dr & Windw interlcks Open drs & windws result in substantial heat lsses. If heat is cut ff when drs are pened, there is an incentive fr peple t keep drs clsed. Simple interlck cntrls are relatively cheap t install and they will link the peratin f heaters s that they switch ff autmatically when drs & windws are pened. Biler sequence cntrl (lad matching, reduced maintenance) Where there are tw r mre bilers (ther than duty & stand-by) with a variable lad pattern, sequence cntrl shuld be installed. If all bilers are firing and shutting dwn simultaneusly, it is likely that they are perating nly at part-lad and d nt have sequence cntrl. Gd sequence cntrl ensures that nly the minimum number f bilers required t meet the heat 40 - Reducing air pllutin frm yur building
Par Hill Research Ltd, Science, Envirnment & Plicy Research A5.3 Time cntrls Time cntrls specify when the heating shuld cme n and fr hw lng. Set crrectly, they ensure the system perates at the best times in terms f building ccupancy and requirements. Time clck (start/stp times) These can range frm simple 24-hur dial time switches with heating either switched n and ff, t seven-day time switches allwing days f the week t be selected r mitted, up t mdern electrnic time switches that allw the heating t be set fr different times, fr different days f the week, summer and winter. The latter give a much higher degree f cntrl and shuld be a minimum requirement. Optimisers (times biler t match ccupancy) An ptimiser is a sphisticated timeswitch linked t the internal and external thermstats that enables the biler t fire at exactly the right time t ensure that the building reaches the required internal temperature in time fr ccupatin, rather than just based n the time switch setting. Similarly, the biler is switched ff early s that the internal temperature is maintained nly when required. Night/weekend setback (24hr heating requirement) This reduces r sets back space temperature during specific time perids, mst cmmnly at night and weekends, when the building is nt fully peratinal. Setback is ften prvided as part f weather cmpensatin & BMS cntrls and is mainly applicable t cntinuusly ccupied premises, fr example, hspitals, nursing hmes r htels. Bst/Extensin timers Prvide greater flexibility if ut-f-hurs heating is required ccasinally. This is a mre efficient ptin than cnstantly reprgramming time switches. If nly a part f the building is t be used, it may be mre ecnmical t prvide lcal heating, and shut the main system dwn. Delayed ff cntrls These are particularly useful where heating needs t be extended beynd nrmal hurs (fr example, evening wrking in shps) r when ccupancy in an area is unpredictable (such as in functin rms). Heating is switched n by the ccupant but autmatically switches ff after a pre-set perid. These are typically fund in split AC units r fan-cil units. PIR/Mtin Detectrs Setback Installatin f a tw-stage thermstat can prvide a setback temperature when an ccupancy sensr detects that a rm is empty. When ccupants return, the thermstat increases the level f heating t the required ccupant temperature. Substantial savings can be achieved depending n building size and ccupatin patterns A5.4 Temperature cntrls Temperature cntrls help heating systems t prvide just the right temperatures t maintain cmfrt withut wasting energy and mney: Thermstats biler/ zne/ rm Wall/Rm thermstat simple rm temperature cntrl. Wireless units are nw available that prvide increased flexibility in psitining and eliminate visible wiring. Prgrammable rm thermstats allw different temperatures t be set fr different perids in the day r week, and prvides a better match t the business wrking pattern. This is imprtant if ccupancy is varied ver the day r week. These can als prvide a night setback feature where a minimum temperature can be maintained at night. Many als allw time cntrl f ht water. Frst Prtectin heating cntrls shuld prtect the building, its cntents, plant and pipewrk frm frst and cndensatin damage. They shuld autmatically switch n heating when the space, external air r return water temperatures fall t pre-set minimum levels (usually belw 5ºC). A separate thermstat may need t be fitted t sme 41 - Reducing air pllutin frm yur building
Par Hill Research Ltd, Envirnment, Plicy & Innvatin simple cntrls. Frst prtectin space sensrs r thermstats shuld typically be installed in the mst vulnerable parts f the building. Zning Buildings frequently have prblematic areas with different time and temperature requirements, where nly ne verall heating r cling cntrl system exists. In this instance zning shuld be cnsidered - where separate time and temperature cntrls are installed fr individual areas. Zned areas will prvide clser, mre efficient heating cntrl. Thermstatic radiatr valves (TRVs) are the simplest and cheapest methd f zning and are useful fr cntrlling individual rms. Cnsider fitting tamperprf TRVs which lck at a fixed setting t prevent staff using them as n/ff switches. Fr larger buildings, install separate pumps and pipewrk t supply each zne, with mtrised valves, zne temperature sensrs and an apprpriate cntrl system. Lcal cntrl +/-2 C thermstats can be put in place t allw a limited degree f cntrl. Fr buildings where there are separate Air Handling Units (AHUs) serving different areas, generally cntrlled thrugh the BMS, cnsider the use f reheats fr sub-znes within these areas. Cnventinal thermstats are inapprpriate fr radiant heating systems s cnsider black-bulb thermstats which are designed t measure radiant heat rather than air temperature. Weather cmpensatin (lad matching) Weather cmpensatin cntrls autmatically adjust biler circuit water flw temperatures t suit the utside temperature, using a sensr utside the building and anther cnnected t the biler. This is mre efficient than the biler turning n and ff, and energy is saved since flw temperature is reduced during milder weather. Fr smaller systems, a cmpensatr can smetimes directly cntrl the biler. Fr areas f ver 1,000m2, fit a weather cmpensatr and mtrised valve t vary the flw f heat t the building. Ensure peratrs are prperly trained All cntrls and BMS systems are nly as gd as the peratrs wh use them. Therefre it is essential that the staff wh will be perating and maintaining the systems are trained apprpriately; and that the settings and any alarms are reviewed regularly. A5.5 Building Management Systems Businesses spending mre than 10,000 a year n energy shuld cnsider installing Building Management System (BMS r BEMs). Building Management Systems (BMS r BEMS) are cmputer systems which cntrl any r all f a buildings services. Intelligent cntrllers, r utstatins, mnitr cnditins thrughut the building, and determine the peratin f the plant such as bilers, pumps, fans, mtrs and lighting in respnse t changing cnditins like time, temperature and light levels. They can be linked using a simple cmmunicatin netwrk, and a PC can be cnnected t this netwrk t bserve their perfrmance and adjust settings. Many systems nw use web based platfrms, allwing management frm anywhere. The main advantage f a BMS installatin is the ease with which users can review the perfrmance f cntrls and cnveniently make adjustments. Other advantages include: Clse cntrl f envirnmental cnditins Data can be lgged and archived fr energy management purpses Rapid infrmatin n plant status Alarms can be autmatically generated, and apprpriate persnnel alerted Identificatin f maintenance requirements, bth planned and reactive (e.g. systems can recrd the number f hurs that mtrs have run, r identify filters n air supply systems which have becme blcked). 42 - Reducing air pllutin frm yur building
Par Hill Research Ltd, Science, Envirnment & Plicy Research A5.6 Getting the best ut f yur cntrls A simple way f assessing the effectiveness f yur heating cntrls is t plt heating energy cnsumptin n a graph and cmpare with perids f building peratin and utside weather cnditins (Heating Degree Days). Des the building shw high energy use ut-f-hurs? Is there a high heating lad when the weather is mild? Is there a pr degree f crrelatin between energy use and cld weather? These are indicatins that cntrl settings are inaccurate r that additinal cntrls are required Check time cntrls are accurate Are they displaying the crrect time and date? Are they adjusted fr daylight savings? Are they set fr the right seasn? D they match wrking hurs Ensure that heating and cling dn t perate at the same time Set cntrls t give a wide gap between the temperatures at which heating and cling systems cut in. Set a gap between f arund 4 5 ºC between the heating and cling thermstat set pints t create a cmfrtable dead band. This will als help t keep ccupants happy. Unless this is implemented, bth systems may perate simultaneusly. 43 - Reducing air pllutin frm yur building