Comparison of life cycle costs of air filters

Transcription

1 Kseniia Vyrysheva T6615KA Comparison of life cycle costs of air filters Bachelor s thesis Building services engineering January 2015

2 Date of the bachelor's thesis 15 th of January 2016 Author(s) Kseniia Vyrysheva Name of the bachelor's thesis COMPARISON OF LIFE CYCLE COSTS OF AIR FILTERS Degree program and option Double Degree Program in Building Services Engineering Abstract The object of this thesis is life cycle costs of the filters. The main aim of this work is to calculate life cycle costs of air filters that are installed in CAV and VAV ventilation systems and compare them between each other. The other aim was to calculate face and media velocities and compare them to guidelines. It was essential to visit technical rooms of A-building and D-building to get all necessary information to perform calculations. These two buildings were chosen as an examples for calculations because A- building has CAV ventilation system and D-building has VAV ventilation system, in particular CO 2- based DCV system. Velocities were calculated in order to see what difference between these velocities would be if instead of bag filter it would be panel filter installed. Results are shown in form of tables. Then these results for A-building and D-building were compare to each other and some conclusions about this comparison were drawn. In this work there is an overview of CAV and VAV ventilation systems, air filters, air filtration, face and media velocities through the filters. Summing it up, it was found out that filters which are installed in VAV ventilation system have smaller life cycle costs than filters which are installed in CAV ventilation system. Subject headings, (keywords) Constant air volume, variable air volume, air filters, air filtration, life cycle costs, face velocity, media velocity Pages Language URN 41 English Remarks, notes on appendices Tutor Luoma Marianna Employer of the bachelor's thesis

3 CONTENTS 1 INTRODUCTION THEORETICAL BACKGROUND Mechanical ventilation systems CAV type ventilation system VAV type ventilation system Air filters and air filtration Mechanisms of filtration Air filters overview Classification of air filters Requirements for air filters Replacement of soiled air filters Disposal of soiled air filters Life cycle costs METHODS Calculations of face velocities of filters Calculations of media velocities of filters Calculations of life cycle costs Investigation of initial data needed in calculations Initial data from A-building Initial data from D-building RESULTS Face velocities of filters Media velocities of filters Life cycle costs of filters in A-building Life cycle costs in D-building Comparison of velocities Comparison of LCCs DISCUSSION LIST OF REFERENCES APPENDICES

4 1 INTRODUCTION 1 Nowadays indoor air quality has started to attract more attention. Cleanliness of the supply air means a lot in achieving proper indoor air quality. That is the reason why we use air filters in ventilation systems. There are three aims in this bachelor s thesis. The first one is to calculate face and media velocities of the filters and compare them between each other. The second aim is to find differences between lifecycle costs of the filters used with CAV and VAV ventilation systems. The third aim is to compare calculated life cycle costs between each other and make some conclusions basing on this comparison. It is expected that life cycle costs of the filters that are installed in VAV ventilation system will be smaller than life cycle costs of the filters that are installed in CAV ventilation system. This work can be divided into three main parts. In the first one, theoretical background, readers can get familiarized with CAV and VAV types of mechanical ventilation systems, air filters and principles of air filtration. Information about life cycle cost can be found in this part as well. This chapter is needed to have an overview of the things this work is about. In the second part of the work velocities and life cycle costs are calculated. In the third part comparison of the results is made. There are also necessary explanations concerning the comparison made.

5 2 THEORETICAL BACKGROUND 2 Ventilation system is supposed to provide fresh and conditioned air to the ventilated premises. It is also made to extract contaminated air to the outside. Overall, there are three types of ventilation systems. The first type is mechanical ventilation systems (supply air and exhaust air fan). The second type is supply air fan with exhaust by leakage through the building envelope, or a natural ventilation system. The third one is ventilation by leakage through the building envelope, in other words no ventilation at all. /1 p. 372./ 2.1 Mechanical ventilation systems Mechanical ventilation systems can be divided into two types. The first one is constant air volume systems (CAV). The second type is variable air volume systems (VAV) CAV type ventilation system CAV ventilation systems were quite common in older commercial like factories, office buildings, and shopping centers before variable air volume systems started to be utilized. Such systems preheat air by means of air handling units (AHUs) with heating coil, and sometimes are also used for air conditioning of spaces if AHUs has cooling coil./3/. The principle difference between VAV and CAV is that in constant air volume systems airflow rate is constant while the supply air temperature changes./1/. CAV systems are designed for demand in so-called «worst case» when the biggest amount of air is to be supplied to the spaces. The working principle of CAV ventilation is so that outdoor air comes to the air handling unit and after being treated in AHU, it goes to the serving spaces with a constant air flow rate. In AHU outdoor air goes through the air filter that arrests pollutants and impurities, heat recovery and heating coil to reach the appropriate temperature. Only temperatures are changed in AHU for CAV system. The only form of control in CAV

6 systems is on/off control. It means that system is just turned on at, for example, 7 a.m. and then turned off at, for example, 21 p.m. 3 CAV is usually used when loads from people do not vary very much as well as heat loads. Advantages of CAV type ventilation is relatively cheap installation and simple control as it can be just switched on and off. The most important disadvantage of this system is high energy consumption and waste of money as a result VAV type ventilation system Variable volume system is designed to decrease energy and maintenance cost. Temperature inside the space is controlled by changing amount of air that is delivered into this space./3./ The working principle of VAV ventilation is so that temperature sensor monitors room temperature and then send signal to VAV controller that in turn changes position of the damper and amount of fresh air that is supplied to the room. Usually VAV controllers are installed on the VAV boxes. Room temperature sensor is a nickel- or platinumresistive element that is sensitive to changes of the temperature in the room. If temperature of room changes, the resistance of the element changes and signal about it is send as a feedback to the VAV controller./3./ Scheme of working principle of VAV ventilation system is presented on Figure 1. FIGURE 1. Scheme of working principle VAV ventilation /3./

7 4 The amount of air that is supplied by the damper depends on the angle at which the damper is positioned./3/. It can be seen on Figure 2, that, for example, when damper is at 90, it is fully closed and new air is not supplied into the room. FIGURE 2. Damper /3./ Variable air volume ventilation systems may be divided into manual operation ventilation systems (MOV) and demand control ventilation systems (DCV). Difference between MOV and DCV is that in DCV systems there is an automatic control of the air flow in relation with demand in the space. Demanded parameter is to be specified. For example, it can be CO2-based demand control ventilation or occupancy based demand control ventilation. In these cases, CO2 or occupancy sensors are installed in the premises./4./ 2.2 Air filters and air filtration Mechanisms of filtration Filtration is a process of removing impurities from the fluid flow. In case of ventilation systems, this fluid is air. There are several mechanisms of that helps to catch the impurities and arrest it in air filter. Each mechanism remove particles of definite size range. The first mechanism is straining. It works when distance between the fibers is smaller than the size of the particle that tries to go through. The second mechanism is inertial separation. If air flow changes the direction, particle in this flow go not change its direction immediately as air does. For some small time it continues to go in the same way and goes exactly into the fiber trap. This method is usually applied when there are lot of coarse particles in the air. The third mechanism is interception. It work when particle size is equal or smaller than the distance between this particle and fiber. In this case,

8 5 particle makes a contact with fiber and is attached to it. The forth principle of filtration is diffusion. It appears when Brownian motion makes a particle clash with a fiber. This mechanism works well when media velocities are low as they are in extended surface area filters. The last mechanism is electrostatic attraction. It works with fibers of relatively big size. This mechanism is supposed to higher the efficiency of removal of fine particles. The principle is so that fiber has charge of one sign and the particle has charge of the other sign so they are attracted together. One more point is that during time this electrostatic attraction decreases because particles accumulate on the fiber and neutralize its charge. On all this mechanisms air filtration is based./5./ Air filters overview Air filters are significant in achieving desired indoor air quality as they reduce amount of transferred pollutants from the outdoors to the indoors. The second purpose of filters is protection of different components of the ventilation systems from being broken because of contaminated air that goes through this components. There are several types of air filters that are used in HVAC systems. The first one is impingement filters. These filters are usually low cost filters which purpose is to remove only coarse impurities from the air. Common examples of such filters are panel filters and roll media filters. The example of panel filter is presented on Figure 3 below./6./ FIGURE 3. Panel filter /7./ The second type is extended surface filters. It is the most widely spread type of filters in HVAC systems nowadays. Extended surface filters have more filter media area than

9 6 area of the filter itself (discharge area of the filter). Increasing of media area helps to decrease average velocities per m 2 of the filter area and increase efficiency of the filters. Pleated filters, bag or pocket filters are examples of extended surface filters./6./ Example of pleated filter is shown on Figure 4 below. Difference between panel filters and pleated filters is illustrated on Figure 5 below. It can be seen that in first case, for panel filter, media velocity is equal to face velocity when area of filter media is 4 ft 2. In this case, face velocity and media velocity through the filter are the same. In the second case, for pleated filter, area of filter media is 12 ft 2 that is three times bigger than for panel filter but face area is the same. In this case, media velocity is three times smaller than face velocity. FIGURE 4. Pleated filter /8./ FIGURE 5. How extended surface filters work /6./

10 7 The third type is gas phase filters. Irritating and odorous gases can be removed with help of gas phase filters. Generally, examples of gas filters are deep bed filters loaded with some agent like active carbon. /6./ The forth one is electronic air cleaners. Electronic air cleaners use active external power source to remove impurities from the air. Their efficiency decreases significantly if they are not maintained properly. Particles that settle down on the collectors should be carefully removed./6./ Classification of air filters Currently used European classification is in accordance with standard EN 779:2012. This classification is based on laboratory tests performed at a test volume flow rate between 0.24 m 3 /s (850 m 3 /h) and 1.5 m 3 /s (5400 m 3 /h) in a rectangular duct with dimensions 610 mm x 610 mm./9./ Classification itself is presented in the Table 1 below. TABLE 1. Classification of air filters in accordance with EN 779:2012 /10./ Filter type EN 779 class Average arrestance Am (%) Average efficiency Em (%) Minimum efficiency (%) Final pressure drop (Pa) Coarse dust filters Fine dust filters G1 Am G2 65 < Am G3 80 < Am G4 90 < Am M5-40 < Em M6-60 < Em F7-80 < Em F8-90 < Em F9-95 < Em In Europe EN 1822:2009 classification of EPA (efficient air filters), HEPA (high efficiency particulate air filters) and ULPA (ultra low penetration air filters) filters is used. The basis of this classification is efficiency on the most penetrating particle size (MPPS). HEPA filters are not commonly used in the field of HVAC but there is some

11 kind of overlap between F8/F7 and EPA filters. In Table 2 below classification of EPA, HEPA and ULPA filters is presented./9./ 8 TABLE 2. Classification of EPA, HEPA, and ULPA filters in accordance with EN 1882:2009 /9./ Filter EN 1882 class Efficiency MPPS (%) Leak test (%) EPA E EPA E EPA E HEPA H HEPA H ULPA U ULPA U ULPA U Requirements for air filters There are several requirements and criteria that should be take into account when selecting and maintaining air filters./9/. As majority of nations claim that global warming is clear and evident, humans have to reduce environmental emissions to decrease the risks of climate changes. The share of buildings in the climate change is approximately considered to be 40% of the total anthropogenic load on the environment. This load is usually quantified by the greenhouse gases emissions. Ventilation system uses about one third of all energy consumed by the building./9./ As far as air pressure drop of the filters play a big role in energy consumption that people are supposed to reduce, it is easy to reach better energy performance by using filters with lower pressure drop. The EPBD (Energy Performance of Building Directive 2002) claim that better energy performance should not decrease the indoor air quality. It is important to respect the initiatives of the EPBD and do not let the indoor air quality to deteriorate at the same time./9./

12 9 In EN 13779:2007 standard indoor air quality in occupied premises is defined in four categories from higher to lower quality. There are no default values for these categories. According to this requirement, air filters can be chosen depending on the degree of outdoor air pollution. Outdoor air quality can be specified in correspondence with local, national or WHO (World Health Organization) requirements. It is said in EN that for hygienic reasons outdoor air should be filtered in two stages with minimum F7 filter quality. For exhaust air the minimum quality filter is M5. In Table 3 below classification of outdoor air and guidelines to use of filters in this outdoor air conditions is presented./9./ TABLE 3. Classification of outdoor air (ODA) and guidelines to use of filters according to EN 13779:2007 /9./ Indoor Air Quality Outdoor air quality IDA 1 (high) IDA 2 (medium) IDA 3 (moderate) IDA 4 (low) ODA 1 (pure air) F9 F8 F7 M5 ODA 2 (dust) F7+F9 F6+F8 M5+F7 M5+M6 ODA 3 (very high concentration of dust or gases) F7+gas filter+f9 F7+gas filter+f9 F5+F7 M5+M6 There is also a German hygienic requirement for HVAC systems VDI 6022:2006. Its general aim is to prevent reduction of indoor air quality because of ventilation system itself. According to this criteria it is important to monitor the relative humidity and keep it below 80% because the higher relative humidity may cause microbial growth. It also requires replacement of the filters after certain periods of operation and minimum efficiency of the filters to avoid dust and microorganisms collecting. It is recommended to use two-stage filtration of outdoor air. The first filter in the air intake should be at least F7 and the second one should be at least F9. One more filter should also be installed downstream the fan to get rid of contaminants from fan drive belt. The minimum exhaust air system filter is F5./9./

13 2.2.5 Replacement of soiled air filters 10 Soiled air filter should be replaced when pressure drop has reached optimal final pressure drop or for hygienic reasons if the second ones appears earlier. It is important to emphasize that, however, classification of coarse and fine filters EN 779 is based on the laboratory tests with final pressure drop of 250 Pa for coarse filters and 450 Pa for fine filters, no filters are designed for such a high pressure drop. Nowadays the most economical and environmentally friendly final pressure drop will be about Pa./9./ They should be replaced after 2000 hours of operation or maximum one year. The filter of second filtration stage and also exhaust filter should be replaced after 4000 hours of operation or maximum 2 years. For hygienic reasons, filters should be removed after the main pollen and spore season in autumn./9./ Before replacing the filter, the date and pressure drop of the filter should be recorded. Visual inspections for leaks are to be done. Problems with faulty air intakes, damaged filters, and incorrectly mounted filters should be taken into account before installing new filters./9./ Disposal of soiled air filters According to legislation, these are the rules applicable to the disposal of air filters: - Organic or combustible waste must be incinerated as they are not suitable for landfill; - All waste must be classified in accordance with EU waste Directive 2000/532/EC; - There are specific regulations for hazardous materials; - The recovery plants have also different acceptance criteria for waste./9./ Re-use is not applicable for air filters because of their dirty condition. Although there are some exceptions when parts of the filter can be cleaned and re-used. Incineration and landfill are the alternative methods of disposal of the air filters. Overall, the biggest part of the filters is to be incinerated./9./

14 2.3 Life cycle costs 11 The last topic to be discussed in theoretical background is life cycle costs (LCC) and life cycle costs analysis (LCCA). A product with the lowest initial price will not necessarily remain the cheapest one for its service life. In the future it may require additional investment. Life cycle cost is an economical conception which main purpose is to give an understanding of how much money is required for products during their whole life in particular./11./ Life cycle costing may also be defined as a mathematical method that is used for supporting any decision./12/. Analysis of life cycle costs is important in establishing, decreasing and overall controlling of costs. It can be applicable in selecting between several alternatives or planning future budget or evaluating new technology as well./11./ The general points of life cycle costs analysis procedure are presented as follows: - The price of all elements includes all money that appear during the life time of the product from installation till final disposal at the end of its working life. All costs must be taken into account precisely and carefully; - Life cycle costs are divided into three stages: development and engineering, production and implementation and maintenance; - There is such a conception as estimating of costs. Relationship in estimating costs may be expressed using some mathematical relation of these costs to one or several independent between each other variables. Costs that were collected during past time may be used as a basis of this estimating process; - Method of LCC calculation is also important. Appropriate method of evaluation of life cycle costs have to be chosen before starting calculations./13./ Stages of life cycle costs can be seen on Figure 4 below.

15 12 FIGURE 6. Life cycle costs stages /13./ The purpose of life cycle costing is to evaluate investment options quite precisely, to take into account all costs, not only the initial ones, make choice between several competing alternative more evident./13./ To make it easier, life cycle costs are divided into elements such as initial costs, life of the product, interest rate, maintenance costs, costs of replacement and disposal, information and feedback and finally uncertainty analysis./13./ Initial costs includes purchasing costs, installation costs and commissioning cost of a product. Prediction of life of a product has a big influence on analysis of life cycle costs and expectations about life of the product can be defined in several different ways. Functional life is a period when there is need in this product. Physical life is a period when the product is expected to last physically until replacement. Technological life is a period till product is replaced because it is changed to technologically more accomplished substituting alternative. Economic life is a period till product is changed to a lower costing substituting alterative. Quite realistic expectations may help to evaluate life cycle costs of a product really precisely. Interest rate helps to take into account effect of future inflation because usually life cycle costs are calculated at the present values. Maintenance costs consists of labor costs, cost of materials, fuel and equipment. Maintenance costs can be divided into smaller categories such as regular planned maintenance, unplanned maintenance in case of faults and periodical maintenance in

16 13 case of refurbishment of a product. Disposal costs include cost of elimination or landfilling or incineration which depends on a product. It may also include costs that selling of a product requires if it is going to be sold. Such element of life cycle costs analysis as information and feedback means that information about a product should be monitored and collected during its life in order to provide some kind of data base for the future. Uncertainty analysis means that life cycle costs are really dependent on the assumptions that were taken into account during calculations and also much depends on collected initial data. Uncertainty may happen, for example, because differences between real and expected behavior of a product happens and this difference straightly has influence on at least the maintenance cost./13./ To reduce an uncertainty to a minimum, initial data for life cycle costs calculations should be collected quite carefully as well as expectations about future behavior of a product are supposed to be based on the past experience or deep literature review. 3 METHODS To achieve aims that were mentioned in the first chapter of the work A-building and D- building of MUAS (Mikkeli University of Applied Sciences) campus were chosen. The choice was so because these buildings have different type of ventilation systems. A- building has CAV ventilation system while D-building has VAV ventilation system. Each building has several air handling units (AHU). LCC and velocities calculations will be made for each AHU separately because all filters that are installed in each AHU are considered as one big filter. 3.1 Calculations of face velocities of filters The definition of face velocity says that it is discharge air flow rate divided by face area of air filter. This definition is expressed in form of equation below. v q / v A (1) where v is filter face velocity, s m A is summarized face area of the filters for AHU, m 2 qv is discharge air flow rate through the filter, m 3 /s

17 14 Summarized face area of the filters for AHU can be found by means of following equation 2: where A A * i * ni Ai 1 * ni 1 Ai n ni n (2) A i is face area of one filter of the type, m 2 n i is number of filters of the type in AHU Face area of one filter of the type can be found as follows: A h * l (3) i i i h i l i is height of face area of one filter, m is length of face area of one filter, m 3.2 Calculations of media velocities of filters Media velocity is velocity through the filter media. It is defined as discharge air flow rate divided by area of filter media. This definition is expressed in equation 3 below. v q / A m (3) v m where vm is filter media velocity, s m Am is summarized area of the filter media for AHU, m 2 qv is discharge air flow rate through the filter, m 3 /s A A * j * n j Aj 1 * n j 1 Aj n n j n (4) where A j is media area of one filter of the type, m 2 n j is number of filters of the type in the AHU Media area of one filter of the type can be found as follows: A h * l *2* n (5) j j j bags

18 where h j l j is height of the bag of one filter, m is length of the bag of one filter, m 15 n bags is number of bags in one filter of the type 3.3 Calculations of life cycle costs Life Cycle Cost is defined as a total cost for any equipment from the moment of its installation to the moment of its final decommissioning. In this method annual energy costs and operating costs during the lifetime are taken into account by the present value. The procedure is made with waste, disposal and other costs. Moreover, method takes into account changes in inflation, interests and prices./9./ In LCC calculation analysis full cost is covered and cost of different elements of lifetime of filter is compared. /9, p. 77./ The life cycle cost can be calculated using the following equation: LCC total I LCC int LCC LCC (6) investment ma enance energy disposal where I investment is the capital costs of the filter installation in case when the ventilation system was first installed. It includes purchasing price of the filter, price of the frame, labor cost and housings of the building volume for the filter, ma enance LCC energy is the present total cost of energy for the filters (the electricity to power the fan), LCC int is the present total purchasing cost of replacement filters including labor costs for replacing the filters, LCC disposal is present total cost for disposing an air filter, /9./

19 To calculate LCC energy average pressure drop is to be known. Its value always depends on the design of the filters and volume flow that goes through the filters. The average pressure drop is usually calculated approximately by the following equation: 16 p avg p p )/ 2 (7) ( ini final where p avg is average pressure drop in the filter, Pa p ini is initial pressure drop of the filter, Pa p final is final pressure drop of the filter, Pa However, the increase of the filters pressure drop is typically faster at the end of its lifetime. So to avoid overestimating of the pressure drop and thus energy consumption that corresponds to the pressure drop of the filter, calculations in this work will be performed with equation (3): p avg p p p )/3 (8) ini ( final ini Energy consumption of the filter can be calculated by the following equation: E ( q * p * t / )/1000 (9) avg where E is energy consumption, kwh q is airflow through the filter, m 3 /s p avg is average pressure drop of the filter, Pa t is efficiency of the fan is time of running of ventilation, h /9 p.71./

20 3.4 Investigation of initial data needed in calculations Initial data from A-building To be able to make calculations, it is needed to get all essential information about the ventilation systems and filters installed in the building. For this purpose, technical rooms were visited and people, who are responsible for maintaining these places, were asked about all the information. The list of questions was as follows: - type of the ventilation system; - working time of the ventilation; - air flow rates; - type of the filters and manufacturer; - serving time; - initial pressure drops. There are four air handling units in A-building. Ventilation system is of the CAV type. Initial information from technical rooms of A-building is presented in Appendix 1. On Figure 6 below example of filter that is installed in A-building can be seen. FIGURE 7. Example of filter that is installed in A-building /14./ The sizing of the filters should be mentioned. Information about dimensions of the filters, its material and price was got from the manufacturer since maintenance person provided the list of filter types installed in A- building. Information about filters that are in use can be seen from the Table 4 below.

21 TABLE 4. Information about types of the filters from manufacturer Type Class EN 779 Material Dimensions (frame dimensions*depth), mm Number of bags 18 Purchasing price, FS-10-F F7 Fiber glass 592*592* ,24 FS-10-F F7 Fiber glass 592*492* ,80 FS-10-F F7 Fiber glass 592*287* ,39 FS-10-F F7 Fiber glass 592*492* ,30 FS-5-F F7 Fiber glass 287*592* ,69 FS-10-M M5 Fiber glass 592*592* ,56 FS-10-M M5 Fiber glass 592*287* ,35 FS-10-M M5 Fiber glass 592*492* ,96 FS-5-M M5 Fiber glass 287*592* ,63 In Table 5 below you can see the list of filters that are included in each AHU and summarized price of filters for each AHU as well. TABLE 5. List of filters and its price for each AHU AHU Type of filters Number of filters of the type Price of one, Price of all of the type, Summarized price for AHU, FS-10-F ,24 456,96 TK-01 FS-5-F ,69 135,38 737,12 FS-10-F ,39 144,78 PK-01 FS-10-M ,56 302,24 FS-10-M ,35 209,4 511,64 FS-10-F ,24 456,96 TK-02 FS-5-F ,69 135,38 737,12 FS-10-F ,39 144,78 PK-02 FS-5-M ,63 523,56 523,56 TK-03 FS-10-F ,24 228,48 FS-10-F ,8 217,6 446,08 PK-03 FS-10-M ,56 151,12 FS-10-M ,96 143,92 295,04 In Table 6 below information about weight of the filters can be found. Weight is needed to find price of landfilling that corresponds to the filters. Weight of the filters is taken approximately from the Camfil Company s brochures./15/. Filters from this manufacturer has almost similar sizes and material in the same. It is done so because it was not possible to find any information about weight of the filters from Suotimet Oy.

22 19 TABLE 6. Information about weight of the filters AHU Type of filters Number of filters of the type Weight of one, kg Weight of all of the type, kg Summarized weight for AHU, kg FS-10-F ,6 10,4 TK-01 FS-5-F ,6 3,2 16,6 FS-10-F ,5 3 PK-01 FS-10-M ,9 7,6 FS-10-M ,2 4,8 12,4 FS-10-F ,6 10,4 TK-02 FS-5-F ,6 3,2 16,6 FS-10-F ,5 3 PK-02 FS-5-M ,2 14,4 14,4 TK-03 FS-10-F ,6 5,2 FS-10-F ,4 4,8 10 PK-03 FS-10-M ,9 3,8 FS-10-M ,6 3,2 7 In accordance with equation 6 price of disposing the air filters and price of energy are needed. Method of disposing replaced filters is landfilling. Landfilling price was taken from the web page of the Finnish company MetsäSairila./16/. Normal price of mixed waste landfilling according to this web-page is 160,73 /ton, including 24% tax. Distributor of energy is ESE Company. Price of energy from is 6,3 snt/kwh Initial data from D-building D-building has CO2-based demand control ventilation. CO2 sensors are installed in the majority of spares but not in all of them. Therefore, it is too complicated to find out an average air flow rate for VAV ventilation system to make LCC calculations. To make further calculations possible, it is assumed that energy savings from DCV system in comparison with average energy consumption of CAV system for schools is 20% for «worst case»./4 p. 25, table 2./ Therefore, energy consumption of DCV system is assumed to be 80% of average energy consumption of AHUs with CAV ventilation system.

23 20 Initial information for D-building was taken from the building automation system program Evalvomo./17/. On Figure 8 example of screenshot from this program for TK-44 can be seen. Initial data from D-building is presented in Appendix 2. In Table 7 below information about types of the filters from the manufacturer is presented. In Table 8 below list of filters and its purchasing prices for each AHU is presented. In Table 9 below information about weight of the filters is presented. FIGURE 8. Screenshot from Evalvomo program for TK-44

24 TABLE 7. Information about types of the filters from manufacturer 21 Type Class EN 779 Material Dimensions (frame dimensions*depth), mm Number of bags Purchasing price, FS-8-F FS-10-F FS-8-M FS-10-F FS-10-F FS-10-M FS-10-F FS-5-F FS-10-F FS-5-F FS-10-M FS-5-M FS-8-F FS-4-F FS-8-F FS-4-F FS-8-F FS-4-F F7 F7 M5 F7 F7 M5 F7 F7 F7 F7 M5 M5 F7 F7 F7 F7 F7 F7 Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass Fiber glass 592x592x ,19 592x592x ,3 592x592x ,44 592x592x ,3 592x592x ,3 592x592x ,04 592x592x ,3 287x592x ,65 592x592x ,3 287x592x ,65 592x592x ,04 287x592x ,91 592x592x ,19 287x592x ,05 592x592x ,19 287x592x ,05 592x592x ,44 287x592x ,71

25 TABLE 8. List of filters and its price for each AHU 22 AHU Type of filters Number of filters of the type Price of one, Price of all of the type, Summorized price for AHU, TK-41 FS-8-F ,19 168,38 360,98 FS-10-F ,3 192,6 PK-41 FS-8-M ,44 134,88 134,88 TK-42 FS-10-F ,3 770,4 1540,8 FS-10-F ,3 770,4 PK-42 FS-10-M ,04 656,32 656,32 FS-10-F ,3 385,2 TK-43 PK-43 TK-44 PK-44 FS-5-F ,65 113,3 FS-10-F ,3 385,2 FS-5-F ,65 113,3 FS-10-M ,04 328,16 FS-5-M ,91 95,82 FS-8-F ,19 336,76 FS-4-F ,05 96,1 FS-8-F ,19 336,76 FS-4-F ,05 96,1 FS-8-M ,44 269,76 FS-4-M ,71 81, ,98 865,72 351,18

26 TABLE 9. Information about weight of the filters 23 AHU Type of filters Number of filters of the type Weight of one, kg Weight of all of the type, kg Summorized weight for AHU, kg TK-41 FS-8-F ,6 5,2 FS-10-F ,6 5,2 10,4 PK-41 FS-8-M ,6 5,2 5,2 TK-42 FS-10-F ,6 20,8 FS-10-F ,6 20,8 41,6 PK-42 FS-10-M ,6 20,8 20,8 FS-10-F ,6 10,4 TK-43 FS-5-F ,6 3,2 FS-10-F ,6 10,4 27,2 FS-5-F ,6 3,2 PK-43 FS-10-M ,6 10,4 FS-5-M ,6 3,2 13,6 FS-8-F ,6 10,4 TK-44 FS-4-F ,6 3,2 FS-8-F ,6 10,4 27,2 FS-4-F ,6 3,2 PK-44 4 RESULTS FS-8-F ,6 10,4 FS-4-F ,6 3,2 13,6 Before starting the life cycle costs calculations the following assumptions need to be taken into account: - The schedule for ventilation is so that it runs on working days from 5 am to 21 pm and on Saturday once per each month from 5 am to 21 pm as well; - Pressure drops that were got in technical rooms are initial pressure drops of the filters because it was only several days since installing the new ones; - Price for housings of the building volume for the filter is ignored; - Efficiency of the fan is considered to be 0.5 in accordance with Eurovent 4/ «Calculation method for the energy use related to air filters in general ventilation systems» guidelines.

27 4.1 Face velocities of filters 24 Calculations for A and D-buildings are presented in Table 10 and Table 11 below. Example of calculations for TK-01 and TK-41 are presented below. For D-building calculations momentary qv were used. For TK-01 qv= 2,9 m 3 /s (from Table 4). Face velocities are found by means of equation 1. Face areas of the filters is found by means of equation 2, where Ai are found with help of equation 3. A A A A A 1 h1 l1 0,592*0,592 0, 35 * m 2 h2 l2 0,287* 0,592 0, 17 * m 3 h3 l3 0,592*0,287 0, 17 * m 1 n1 A2 * n2 A3 * n3 0,35*4 0,17*2 0,17*2 2, 08 * m v qv / A 2,9 / 2,08 1,39m / s TABLE 10. Face velocities for A-building AHU Type of filters ni hi, m li, m Ai, m2 A, m 2 qv, m 3 /s v, m/s FS-10-F ,592 0,592 0,35 TK-01 FS-5-F ,287 0,592 0,17 2,08 2,9 1,39 FS-10-F ,592 0,287 0,17 PK-01 FS-10-M ,592 0,592 0,35 FS-10-M ,592 0,287 0,17 2,08 4,6 2,21 FS-10-F ,592 0,592 0,35 TK-02 FS-5-F ,287 0,592 0,17 2,08 4,8 2,31 FS-10-F ,592 0,287 0,17 PK-02 FS-5-M ,287 0,592 0,17 2,04 5,3 2,6 TK-03 FS-10-F ,592 0,592 0,35 FS-10-F ,592 0,492 0,29 1,28 5,6 4,36 PK-03 FS-10-M ,592 0,592 0,35 FS-10-M ,592 0,492 0,29 0,99 5,45 5,49 For TK-41 qv= 2,8 m 3 /s (from table 8). Face velocities are found by means of equation 1. Face areas of the filters is found by means of equation 2, where Ai are found with help of equation 3.

28 25 A A 1 h1 l1 0,592*0,592 0, 35 * m 2 h2 l2 0,592* 0,592 0, 35 * m 2 2 A A 1 n1 A2 * n2 0,35* 2 0,35* 2 1, 4 * m 2 v qv / A 2,8/1,4 2m / s TABLE 11. Face velocities for D-building AHU Type of filters ni hi, m li, m Ai, m2 A, m 2 qv, m 3 /s v, m/s TK-41 FS-8-F ,592 0,592 0,35 FS-10-F ,592 0,592 0,35 1,4 2,8 2 PK-41 FS-8-M ,592 0,592 0,35 0,7 2,4 3,42 TK-42 FS-10-F ,592 0,592 0,35 FS-10-F ,592 0,592 0,35 5,61 8,1 1,44 PK-42 FS-10-M ,592 0,592 0,35 2,8 8,5 3,03 FS-10-F ,592 0,592 0,35 TK-43 FS-5-F ,287 0,592 0,17 FS-10-F ,592 0,592 0,35 3,48 3,6 1,03 FS-5-F ,287 0,592 0,17 PK-43 FS-10-M ,592 0,592 0,35 FS-5-M ,287 0,592 0,17 1,74 2,8 1,61 FS-8-F ,592 0,592 0,35 TK-44 FS-4-F ,287 0,592 0,17 FS-8-F ,592 0,592 0,35 3,48 3 0,86 FS-4-F ,287 0,592 0,17 PK-44 FS-8-F ,592 0,592 0,35 1,74 2,4 1, Media velocities of filters Calculations for A and D-buildings are presented in Table 12 and Table 13 below. Examples of calculations for TK-01 and TK-41 are presented as well. For TK-01 qv= 2,9 m/s (from Appendix 1). Media velocities are found by means of equation 3.Media area of the filters is found by means of equation 4, where Aj are found with help of equation 5. A * bags m 1 h1 l1 *2* n 0,592*0,6*2*10 7, 10 A * bags m 2 h2 l2 *2* n 0,287*0,6*2*5 1,

29 26 A * bags m 3 h3 l3 *2* n 0,592*0,6*2*10 7, 10 2 A A 1 n1 A2 * n2 7,10* 4 1,72* 2 7,10* 2 46, 07 * m vm qv / Am 2,8/ 46,07 0,06m / s 2 TABLE 12. Media velocities for A-building AHU Type of filters ni nbags li, m hi, m Ai, m Am, m 2 qv, m 3 /s vm, m/s FS-10-F ,6 0,592 7,10 TK-01 FS-5-F ,6 0,287 1,72 46,07 2,9 0,06 FS-10-F ,6 0,592 7,10 PK-01 FS-10-M ,33 0,592 3,91 FS-10-M ,33 0,592 3,91 31,26 4,6 0,15 FS-10-F ,6 0,592 7,10 TK-02 FS-5-F ,6 0,287 1,72 46,07 4,8 0,10 FS-10-F ,6 0,592 7,10 PK-02 FS-5-M ,33 0,287 0,95 11,37 5,3 0,47 TK-03 FS-10-F ,6 0,592 7,10 FS-10-F ,6 0,592 7,10 28,42 5,6 0,20 PK-03 FS-10-M ,33 0,592 3,91 7,81 5,45 0,70 For TK-41 qv= 2,8 m/s (from table in Appendix 2). Media velocities are found by means of equation 3.Media area of the filters is found by means of equation 4, where Aj are found with help of equation 5. A * bags m 1 h1 l1 *2* n 0,592*0,5*2*8 4, 74 A * bags m 2 h2 l2 *2* n 0,592*0,5*2*10 5, A A 1 n1 A2 * n2 4,74* 2 5,92* 2 21, 31 * m vm qv / Am 2,8/ 21,31 0,13m / s 2

30 TABLE 13. Media velocities for D-building 27 AHU Type of filters ni nbags li, m hi, m Ai, m Am, m 2 qv, m 3 /s vm, m/s TK-41 FS-8-F ,5 0,592 4,74 21,31 2,8 0,13 FS-10-F ,5 0,592 5,92 PK-41 FS-8-M ,5 0,592 4,74 9,47 2,4 0,25 TK-42 FS-10-F ,5 0,592 5,92 FS-10-F ,5 0,592 5,92 94,72 8,1 0,09 PK-42 FS-10-M ,5 0,592 5,92 47,36 8,5 0,18 FS-10-F ,5 0,592 5,92 FS-5-F ,5 0,287 1,44 TK-43 FS-10-F ,5 0,592 5,92 53,10 3,6 0,07 FS-5-F ,5 0,287 1,44 PK-43 FS-10-M ,5 0,592 5,92 FS-5-M ,5 0,287 1,44 26,55 2,8 0,11 FS-8-F ,5 0,592 4,74 FS-4-F ,5 0,287 1,15 TK-44 FS-8-F ,5 0,592 4,74 42,48 3 0,07 FS-4-F ,5 0,287 1,15 PK-44 FS-8-F ,5 0,592 4,74 18,94 2,4 0, Life cycle costs of filters in A-building Calculation are performed in table form. Table with detailed results for A-building is presented in Appendix 3. Example of calculations TK-01 is presented below. For calculating Iinvestment purchasing prices of filters for each AHU were taken from table 6. For TK-01 purchasing price of filters is 737,12. Labor costs were calculated basing on the assumption that maintenance person need about 45 minutes to either install or replace all separate filters from one AHU. Therefore, it was assumed that cost of one working hour of maintenance person is 50 so labor costs are 37,5. I investment 737,12 37,5 774,62 In this case LCCmaintenance is the same as Iinvestment. It is so because usually air handling unit is provided by manufacturer in its final condition but in this work is assumed that all the parts of air handling unit are provided separately to simplify the calculations.

31 28 LCC maintenance 774,62 Energy consumption of the filter is calculated in accordance with equation 9: E ( 2,9 *123,3* 4032/ 0,5) / , 22kWh Time is calculated in accordance with ventilation schedule: t 12h *5d *4w*12m 12h *1d *1w *12m 4032h Pavg is calculated in accordance with equation 8: p avg 60 (250 60)/3 123, 3kPa So LCC 2884,22*0,06 173,05 energy For LCCdisposal weight of filters is taken from table 6. Landfilling price is 160, 73 /ton. LCC disposal 160,73*0,01 2,73 In accordance with equation 6 total life cycle costs are as follows: LCC total I investment LCC maint enance 774,62 173,05 2, ,03 LCC energy LCC disposal 774, Life cycle costs in D-building Calculation are performed in table form. Table with detailed results for A-building is presented in Appendix 4. Example of calculations TK-41 is presented below. For calculating Iinvestment purchasing prices of filters for each AHU were taken from table 8. For TK-41 purchasing price of filters is 360,98. Labor costs were calculated basing on the assumption that maintenance person need about 45 minutes to either install or

32 replace all separate filters from one AHU. Therefore, it was assumed that cost of one working hour of maintenance person is 50 so labor costs are 37,5. 29 I investment 360,98 37,5 398,48 In this case LCCmaintenance is the same as Iinvestment. It is so because usually air handling unit is provided by manufacturer in its final condition but in this work is assumed that all the parts of air handling unit are provided separately to simplify the calculations. LCC maintenance 398,48 Energy consumption of the filters is calculated basing on the assumption that energy consumed by VAV system is 80% from the average consumption by CAV system. It is also taken into account that amount of working hours is different. Working hours of VAV system per year equals to 2400 hours. Time was calculated in accordance with ventilation working hours. The average energy consumption for CAV is 4390,3 and its working hours per year equals to 4032 hours. Therefore, calculations of energy in this case are as follows: E 0,8* 2400* 4390,3 / , 62kWh So LCC 2090,62*0,06 125,44 energy For LCCdisposal weight of filters is taken from Table 9. Landfilling price is 160, 73 /ton. LCC disposal 160,73*0,01 1,61 In accordance with equation 6 total life cycle costs are as follows: LCC total I investment LCC maint enance LCC energy LCC disposal 398,48 398,48 125,44 1,61 924,00

33 4.5 Comparison of velocities 30 Comparison of face and media velocities for A-building is presented in Table 16 below. It can be seen that media velocity is 2-6 % from face velocity through the filters. The average value is 4%. TABLE 16. Comparison of face and media velocities for A-building AHU v, m/s vm, m/s vm/v, % TK-01 1,39 0,03 2 PK-01 2,21 0,09 4 TK-02 2,60 0,06 2 PK-02 2,31 0,13 6 TK-03 4,36 0,12 3 PK-03 5,49 0,33 6 average 4 Comparison of face and media velocities for D-building is presented in Table 17 below. It can be seen that media velocity is 8-28 % from face velocity through the filters. The average value is 17%. TABLE 17. Comparison of face and media velocities for D-building AHU v, m/s vm, m/s vm/v, % TK ,16 8 PK-41 3,42 0,6 18 TK-42 1,44 0,41 28 PK-42 3,03 0,85 28 TK-43 1,03 0,12 12 PK-43 1,61 0,19 12 TK-44 0,86 0,13 15 PK-44 1,38 0,2 14 average Comparison of LCCs Comparison of life cycle costs of A-building and D-building is presented in Table 18 below.

34 31 TABLE 18. Comparison of LCCs of A-building and D-building LCCtotal for A- building, LCCtotal for D- building, 1725,03 924, ,78 478, , , , , ,30 938, , ,20-941,51 average 1424,03 average 1584,86 For A-building in last cells information is missing because there are two less AHUs. 5 DISCUSSION In this thesis differences between face and media velocities of the same filters were checked basing on the real case. The average face velocity for A-building is 3,06 m/s. The average face velocity for D-building is 1,85 m/s. The average media velocity for A-building is 0,13 m/s. The average media velocity for D-building is 0,33 m/s. Big difference between face velocities and media velocities is the reason of implementing extended surface area filters because the lower is velocity, the better is ability of filters to arrest impurities. Average face velocities also can be compared to values of energy efficient criteria for velocities. It is said in EN 13779:2007 that 2,5 m/s corresponds to poor design, 2,0 m/s corresponds to typical design and 1,5 corresponds to good design./18./ Average face velocity for A-building corresponds to poor design and value for D-building corresponds to typical design. It can be seen from Table 14 below that investment costs are about % from the total life cycle costs for A-building. The average value is about 40 % for A-building. It is less than it would be in real life because of assumptions that were taken into account in this work.

35 32 TABLE 14. Share of the of Iinvestment costs from the total LCCtotal for A-building AHU Iinvestment, LCCtotal, Share of Iinvestment from LCCtotal, % TK , ,03 44,9 PK , ,78 41,51 TK , ,37 41,44 PK , ,29 41,03 TK , ,61 PK ,54 938,69 35,43 average 40,15 For D-building investment costs are about %. The average value is 43 % do D- building. It can be seen from the Table 15 below. TABLE 15. Share of the of Iinvestment costs from the total LCCtotal for D-building AHU Iinvestment, LCCtotal, Share of Iinvestment from LCCtotal, % TK ,48 924,00 43,13 PK ,38 478,23 36,05 TK , ,16 46,50 PK , ,82 42,78 TK , ,30 46,03 PK , ,65 41,97 TK , ,20 42,74 PK ,68 941,51 42,68 average 42,73 Therefore, for both buildings average shares of investment costs from the total costs are almost similar. The main aim of this work was to compare life cycle costs of the filters installed in different types of ventilation systems. Results from Table 18 did not support an earlier

36 33 expectation that filters that are installed in VAV ventilation system has smaller life cycle costs than filters that are installed with CAV ventilation system. For A-building LCCs are 11 % smaller than for the D-building. The reason of such result is that compared buildings have different number of filters and as a result different purchasing prices for them. For instance, AHUs in A-building have pre-filters on the supply and AHUs from D-building do not have any of those. The average purchasing price for AHU for A-building is 541,76 and for D-building this price is 666,36. It still seems that in case of similar purchasing prices, filters that are installed in VAV would have smaller life cycle costs because share of purchasing prices of filters is about 60 % of all costs. It is so because these prices are included not only in investment costs but also in cost of maintanance.

37 LIST OF REFERENCES Nilsson, Per Erik. Achieving the Desired Indoor Climate: Energy Efficiency Aspects of System Design. Narayana press. Denmark Nebil Ben-Aissa, Johnson Controls, Inc. Heating, Ventilation, and Air Conditioning (HVAC) Controls: Variable Air Volume (VAV) systems. WWW document. Updated Referred Danfoss. Application note. Improving CAV ventilation systems. WWW document. Updated Reffered Emmerich Steven, Persily Andrew. State-of-the-Art Review of CO2 Demand Controlled Ventilation. Technology and Application. United States of America. National Institute of Standards and Technology. PDF document. Updated Referred Camfil. Principles of filtration. WWW document. Updated Reffered Troy Filters, Ltd. HVAC filtration 101. Basics of HVAC filtration. PDF document. Updated Reffered The online industrial exhibition. Direct Industry. Panel filter. WWW document. Updated Reffered