Executive Summary - Computer Action Team



Executive SummaryThis report provides evaluated and on-site experimental data as well as design suggestions to meet the primary client requirement: to provide occupancy comfort in the Mt Angel Library in Mt Angel, Oregon. While choosing upgrades to the existing systems the team noted that modifications to the existing glazing, overhangs, or roof/wall construction are not acceptable because of the building’s historic value. To meet the building’s peak cooling demand, two different cooling coil options and two chiller options were reviewed. To ensure the overall effectiveness of the system, servicing and renovations for the air handling system were also considered.One of the cooling coil options is to use a large single cooling coil to condition the main supply plenum. Another option is to use 16 individual cooling coils in the ducts to provide better zonal control. Air cooled and water cooled chillers were considered as options to supply the cooling needed. As a finalized model, two alternatives are recommended to achieve the project goals. The first alternative is a complete system with central cooling, zone air volume control and direct digital system controls. The second alternative consists of four design phases aimed at achieving the project goals incrementally.This report addresses existing thermal comfort issues, on-site testing data, results from computer simulations, calculations to size system components, and cost analysis for each component. The team generated RTS and eQuest cooling-heating models using system design plans and onsite measurements. Greenheck coil selection software verified cooling coil size calculations. CONTENTS TOC \o "1-3" \h \z \u Executive Summary PAGEREF _Toc200998864 \h 1Introduction PAGEREF _Toc200998865 \h 3Mission Statement PAGEREF _Toc200998866 \h 3Product Design Requirements PAGEREF _Toc200998867 \h 4Current System Assessment PAGEREF _Toc200998868 \h 5Retrofit Equipment Simulations PAGEREF _Toc200998869 \h 10Available Design Options PAGEREF _Toc200998870 \h 10Design Evaluation PAGEREF _Toc200998871 \h 14Final Design Recommendations PAGEREF _Toc200998872 \h 15Conclusions PAGEREF _Toc200998873 \h 21References PAGEREF _Toc200998874 \h 22Appendices PAGEREF _Toc200998875 \h 23IntroductionMs. Victoria Ertelt, the Mt.Angel Abbey library administrator first approached the Capstone class in early September 2011 to introduce her project. During the initial presentation, Ms.Ertelt described the project background and her expectations from the Capstone team. Since November 2011, the team has had meetings with the client to identify the direction and scope of the project. Mt. Angel Abbey library was built in 1970. It is a 46,000 square-foot, three-story library with an insufficient HVAC system for its current needs. The existing air-handling unit is a multizone unit, which provides heating and ventilation only. The main supply plenum feeds 16 individual zone ducts. Each duct contains a hot-water heating coil for zonal heating. The outside-air damper is set at 21% open throughout the year due to a malfunctioning pneumatic actuator. As a result of not having a minimum control system and a cooling method, the thermal comfort in the overall library is significantly affected. The library holds over 5000 rare books and antiquities, and is a resource—architecturally and educationally--for a number of students and visitors. The Capstone team has been tasked with evaluating the current HVAC system and recommending modifications to meet the desired thermal comfort levels that will make the library a more enjoyable environment for occupants and improve storage conditions for the books.Mission Statement The objective of this Capstone project is to propose cost effective and efficient changes to the Mt Angel Library HVAC system that will maintain a desired temperature and humidity to meet occupancy comfort and provide for the safe storage of books. The team will use computer-aided simulations from eQuest and an RTS cooling-heating spreadsheet to verify the project goals. Data loggers will be used to collect temperature, humidity information to calibrate the computer model in order to generate accurate information about the library.Product Design Requirements The major client requirementsThermal comfort in the librarySafe environment for book storageThe minor client requirementsLow first costLow energy costThe major/minor ASHRAE requirementsMajor:ASHRAE standard 55-2004, Thermal comfort for occupantsASHRAE standard 62.1-2004, Ventilation and indoor air quality ASHRAE requirements for preservation of public collections (library specific standard)MinorSystem needs to generate less than 40 Decibels of background noiseCurrent System AssessmentRadiant time series (RTS) analysis provides a rough system loads analysis. A spreadsheet with typical mean data for peak temperature extremes for a chosen climate is applied to basic glazing and building envelope parameters. The end result is an estimate of peak heating and cooling requirements as well as an annual energy consumption estimate (appendix E). This is the basis for comparison in more sophisticated energy simulation. The eQuest building energy simulation tool has two fundamental parameters that control its output: a building file and a weather file. The weather file was a typical mean year, which represents a likely weather exposure of the building. The closest weather station with an e-quest formatted TMY file is located at the Salem OR airport, which is about 21 miles away. The focus points of this model were orientation, construction properties, glazing, infiltration, internal gains, and mechanical equipment.The building is oriented with the majority of the glazing facing the Northeast. The large percentage of glazed area (20%) contributes to solar heat gains in all perimeter spaces, as well as added conduction and infiltration losses. To capture the complex orientation of the glazing, the building plan was traced and the detailed window plan was replicated in the e-quest model. Skylights with similar orientation and area to those in the building plans were also placed on the roof of the library. The building envelope has three important exterior components: exterior walls, roof, and foundation. The details of construction for the e-quest model were taken from the original building plans by Alvar Aalto.Table SEQ Table \* ARABIC 1: eQuest detail building construction Envelope ElementConstruction ElementConstruction ElementConstruction ElementConstruction ElementConstruction ElementU-Value (BTU/hr/ft^2)Exterior walls4 inches brick3 inches LW concrete4 inches brick0.178RoofRubber tileBuilt up Roof6 inches MW concreteAir layerAcoustic Tile0.208Floor6 inches concreteCarpet0.358 There are three major types of glazing included in the model all of which were verified visually and with a Glasscheck Pro. glazing measurement device.Table SEQ Table \* ARABIC 2 : Detailed glazing dataGlazing ElementGlass Thickness (mm)SHGCFrameCenter of glass U value BTU/hr/ft^2Operable Window30.84Aluminum W/O brake1.23Inoperable Window30.84Aluminum W/O brake1.12Glass entryway Doors30.84Aluminum W/O brake1.05Infiltration and ventilation account for the majority of energy exchange with the outside environment, in buildings that have a high volume to surface area ratio. Therefore the most heavily weighted parameter in model validation was infiltration which was estimated at 1.55 cubic feet per minute per square foot of exterior surface, and 0.03 cubic feet per minute of floor area in interior zones. Specific planned ventilation values are addressed in the mechanical components section.Internal gains are heat producing elements inside of a building envelope. The loads added by building occupants in the e-quest model are governed by schedules and are not a large source of heat compared to heat gains from equipment and lighting. Lighting densities were determined by default values in eQuest for an office building. Table SEQ Table \* ARABIC 3: eQuest lighting density Type of SpaceLighting density W/m^2Work/Reading Area1.465Break room and Restrooms1.392Counting each appliance type and summarizing their typical power consumptions for each zone determined internal gains for office equipment and appliances. The usage fraction in eQuest was left as the default for each equipment type.Table SEQ Table \* ARABIC 4: eQuest, internal gains by appliance (Appliance)Space Name (Zone Name)Office Equipment (Kilowatts)Cooking Equipment (Kilowatts)Refrigeration Equipment (Kilowatts)Cataloguing Room.3700Circulation Desk.10002nd Floor Stacks.11001st Floor Stacks.5300Printing Area.9000Head Librarian Office.1000Staff Room01.17.70Server Room7.4600Mechanical equipment determines how a building controls its internal environment. The key elements in the existing library HVAC are the supply fan, exhaust relief fan, and the whole campus steam boiler. The steam boiler is designed to provide a load for the whole campus so only the library requirement is included in the model parameters. The design load provided by individual zone heating coils is detailed in appendix I.Table SEQ Table \* ARABIC 5: Boiler, Supply Fan, Return FanComponentEfficiencyDetailed InputsBoiler0.67-1.574 MBTU/hrSupply Fan0.3340 HP, 41673 CFMReturn Fan0.3326 HP, 32551 CFMThis HVAC system was originally designed to have an air-side economizer. Currently the damper motors do not work so the system is set to a fixed outside air percentage of 21%.The resulting simulation indicates the following peak loads:Table SEQ Table \* ARABIC 6: Summary of cooling peak loadsZoneHC11 (Carrels)HC16 (1st Floor Stacks)HC1 (3rd Floor Stacks)HC2 (3rd Floor Stacks)All Other ZonesSumCooling Peak Loads KBTU/HR114.858159.98390.049117.158894.0781376.126MonthAUGAUGAUGAUGJUN-AUG?This model was verified by examining detailed temperature outputs. The data was generated for the 15th of January through the 14th of May. Data loggers in the catalog room (Zone HC9) and a study carrel (Zone HC11) showed the following data after the whole building’s infiltration rates were adjusted to 1.55 CFM per square foot of exterior wall.Figure SEQ Figure \* ARABIC 1: Comparison of BIN data in the First Floor between collected values from Data loggers and eQuest generated modelFigure SEQ Figure \* ARABIC 2: Comparison of BIN data in a Study Carrel between collected values from Data loggers and eQuest generated modelThe collected data is more concentrated in the 65-80 F° range than the model, although still very close in terms of density of values. This variation is caused by two factors in particular. The typical mean year for a nearby weather station was used for the model instead of the data specific to Mount Angel this year. The data generated for the zones is a mean for those zones while the data loggers represent discreet locations in the center of the zone. Even though the match is not perfect, the model is still representative of Library for the pruposes of estimating peak loads and energy use.Retrofit Equipment SimulationsAfter a baseline model was developed, mechanical equipment could be added or removed to determine its effect on energy savings. The savings calculated justify each component individually so that a payback period may be estimated for each component. The variations in each model run are as follows:Table SEQ Table \* ARABIC 7: eQuest baseline model and variations to the modelModel RunBaseline ModelChanges From BaselineVariable Frequency DriveCurrent SystemFans are variable speed with 50% efficiencyDemand Control VentilationCurrent SystemTotal ventilation set by critical zoneDirect Digital ControlsAny SystemAverage electrical and gas savings estimated at 15%Zone Volume Control DampersVariable Frequency DriveSystem type is variable air volumeChiller OnlyBaseline ModelAir cooled chiller and single zone water chilled coil addedEconomizerChiller OnlyOutside air intake controlled by thermostat. Operates between 55 and 62 degrees FFull UpgradeCurrent SystemAll changes listed aboveThe savings for each component are addressed in final design recommendations (Table 10 for monitory savings) and in appendix F (energy savings by component).Available Design OptionsCooling CoilAs a means of cooling the library, chilled water will be used to remove heat from the supply air. The type of heat exchanger that is typical for this application utilizes a finned tube (mixed air-unmixed water) arranged in a series of rows and packaged into a “cooling coil” that includes a drain pan to collect condensate. In the Mt.Angel library application, two different methods of implementing cooling coils have been studied to provide the required cooling load of 120 tons. One method is to locate one large central coil between the mixing chamber and the supply fan. This method will require zone control to regulate zone temperatures (see VFD and Zone Control Dampers section, below).Another method is to install 16 individual coils in the zone ducts. This option will appropriately condition the air going into different zones by individually controlling the coils. Installing multiple coils will require a more extensive network of chilled water supply piping as well as drain lines to the sixteen coils. Each coil will require a supply valve, actuator and tie-in to the control system. VFD and Zone Control DampersThe use of a central cooling coil will provide cooling sufficient to cool air in the zone with highest cooling load. This will produce overcooling in zones where the cooling load is significantly lower. Using the heating coils in each zone duct to reheat the air is one method to control zone temperature. While this method has no additional upfront cost, the energy use to supply reheat adds to the operating cost of the system.A more energy efficient method of zone temperature control is to install automatically-controlled individual zone volume dampers in each branch duct in place of the manual damper that currently exists upstream of the heating coil. This damper would modulate air volume based on cooling load requirements in each zone. Another typical component in this application is a variable air volume (VAV) box, which includes an electric reheat coil. With individual heating coils in each zone duct, the extra cost associated with a VAV box is not justified. With a variable air volume damper in each zone, the supply and return fans must vary their flowrate to match the demand so that pressure is balanced in the system. The use of a variable frequency drive (VFD) on the supply and return fans regulates speed to match demand. In the retrofit of an older system, it is typical to replace the fan motor with a variable speed model in addition to adding the drive. The addition of a VFD will add additional energy savings year round by reducing fan power consumption. Implementation of the automatic zone dampers and VFD requires integration into an effective controls system.ChillerChillers are refrigeration systems which cool a fluid through a vapor-compression refrigeration cycle to afford a desirable and comfortable environment. In general, chillers have some basic components such as evaporators, compressors, condensers, and recirculation pumps. Air-Cooled and Water-Cooled chillers are the main two types of chillers.Air-cooled chillers have condensers that use the surrounding atmosphere (Air) as the cooling medium to extract heat from the refrigerant. Usually a condenser fan is used to force the air over the condensing coils to maximize cooling. Air-cooled chillers produce cold refrigerant that can be transmitted through pipes and pumps to a large number of envelope zones. No freeze protection is needed in air-cooled condensers since they operate below the freezing point. This type of chiller does not require a mechanical room, condenser pumps, or cooling tower. Moreover, air-cooled chillers require less maintenance and have low installation costs.As for Water-cooled chillers, they use water to cool the refrigerant. Water exits the chillers warmed which needs to be cooled usually through cooling towers, where the cooled water enters the condensers again and the cycle is repeated. Water-cooled chillers have large refrigerating capacities, long service life, and high efficiencies that make them favorable for large industrial and commercial applications. This type of chiller is available as a closed loop system or a split system. Both systems are usually installed indoors. A readily available water supply is required and a water treatment plan should be scheduled since water has a corrosive effect on metal coils. A table is shown in Appendix G, which compares the cost, efficiency, capacity, maintenance and availability of air-cooled and water-cooled chillers.Controls and System PerformanceThe original controls for the HVAC system use pneumatic actuators to control heating coil supply valves, a steam supply valve and damper motors. Input from temperature sensors that measure return air, outside air and mixed air is used to modulate the dampers. The outside air temperature sensor supplies input to the heating supply controller that modulates the steam supply valve to provide adequate heating water and pneumatic thermostats modulate zone heating coil valves. Additionally, smoke sensors located in the return air send input to fan motor controllers to prevent fan operation when smoke is present.The system was designed to operate the supply, return, and exhaust fans as well as the heating pump as scheduled on the building time switch. A manual spring wound timer was designed to be used to operate the system during unscheduled hours. The dampers are modulated to prevent the mixed air temperature from falling below 55°F. As well, dampers are set to remain in the full recirculating position when the supply fan is off or the return air temperature is below 70°F.The system was designed with an air-side economizer cycle which takes advantage of free cooling when outdoor air temperatures are low enough (approximately 62°F) and there is a cooling load. Increased levels of outdoor air above ventilation requirements are brought in to cool return air without the use of mechanical cooling. The effective performance of this system is dependent on precise control of the outdoor, return and exhaust air dampers as well as adequate mixing of outdoor and return air in the mixing plenum.Air flow through the system is balanced using manual volume dampers. These are located at the beginning of each zone branch line upstream of the heating coil and at each supply and return diffuser. Access panels at each location are provided for manual balancing. Periodic system balancing is necessary to maintain even pressure and conditioned air distribution in the library.Over the 40 years since installation, the HVAC system-- including the controls--has received irregular maintenance. Inoperable damper actuator motors are evidence of a need for routine system inspection. As well, periodic thermostat calibration and zone damper balancing have not been performed. Pneumatic control systems have a life span of 25-30 years. The air supply system which includes the compressor, drier, filters and regulators becomes contaminated with oil, water and dirt and causes fouling of the field devices over time. While the system is still functional, its performance is not optimal at present and is nearing or beyond its useful service life. In order to continue the use of the pneumatic system and operate it at optimal performance, all field devices should be inspected , tested and recalibrated. The continued use of this control system would require replacement of any actuators, valves, damper motors or thermostats that are not functioning. The pneumatic lines and fittings should be inspected for leaks and blockages. Also, the damper positions and linkage condition should be inspected to insure that positions match desired setpoints.Conversion to a direct digital control (DDC) system would provide significant energy savings and offer greater control over the HVAC setpoints, proportional or integral gains, minimum on and off times, high or low limits, night-flush cycles and tighter control of the economizer cycle.DDC would also allow for integration of demand-controlled ventilation (DCV). DCV uses CO2 sensors to modulate the outdoor air damper to meet minimum ventilation requirements based on occupancy, thus reducing the energy used to heat or cool excess outdoor air. Another advantage of DDC would be to incorporate humidity control using the cooling coil. Humidistats could be placed in zones with the highest levels of humidity. If humidity levels exceeded setpoints, chilled water from the chiller would be demanded and regulated through the coil control valve.Installation of a new central cooling coil, chiller and volume control dampers will require actuators and integration into the system controls. The options for this include:Pneumatically controlled actuators tied into the existing pneumatic control systemElectronic-to-pneumatic transducers to retrofit the existing pneumatic system to digital controllers and thermostatsCompletely new electric actuated direct digital control (DDC) system.The option with the least up front cost would be the use of pneumatic actuators tied into the existing pneumatic system. This option would of course be dependent on the inspection, testing and calibration of the existing system. Upfront costs would include, in addition to the actuators and pneumatic lines and installation, the costs associated with restoring the existing system to its optimal performanceDesign EvaluationNote:**All the components are described in the previous section**Table SEQ Table \* ARABIC 8: Design decision matrix: each recommendation is ranked on a scale of 1 to 10 (lowest to highest influence) with respect to each criteria. ?CriteriaRecommended upgradesServicing existing system Replacing malfunctioned controlsDirect Digital Controls (DDC)Variable Speed Drive (VFD)Cooling coil Volume Control DampersDemand Control VentilationCost9624637Performance56788103Thermal Comfort5677895Book Preservation4567891Total23232326302916Final Design Recommendations Note:This project report has excluded the section dedicated for “Top-level design alternatives”. Rather than concluding with a final design, this report consists only of design recommendations. The design team was not given a project budget by the client for the final design. Therefore, two alternative solutions were proposed to accommodate various levels of funding. The first alternative is a complete system that will provide mechanical cooling , takes advantage of some energy saving measures and provides precise system control. The second alternative is a four phase installment plan. The four design phases have been assessed with the consideration of least upfront cost to highest upfront cost. Even though the first option can be classified as the least expensive option, it consists of upgrades to the current system in order to meet minimal design requirements.Below are the detailed final design alternatives:Design Alternative I: Complete Mechanical Cooling SystemBased on the peak-cooling load generated by the eQuest energy model, it was determined that the library would need 120 tons of cooling. The recommended system to accomplish the thermal comfort needs of the library includes an air-cooled chiller, a central cooling coil, return and supply fan VFD’s with new variable speed motors, automatic zone control dampers and a complete DDC control system with DCV and humidistats. These items are detailed below in the Design Alternative II section. Estimated costs for this system are $160,000 for the equipment and $180,000 for the installation for a total of $340,000 in project costs. This is a rough estimate based on industry rules of thumb (See Appendix E). While a multi-phase alternate to the complete system is proposed in this report, the library will save money and have a more comprehensive plan by completing all of the work at one time. Contractors’ bids are likely to be more cost effective when considering completion of the work at one time. As well, spending money to rehabilitate components that have exhausted their useful service life may not make the most economic sense. Design Alternative II: Four-Phase Installment PlanPhase 1: Existing System OverhaulInspect and test pneumatic control system Check lines for leaks and air, oil or moisture contaminationTest valves, damper motors and actuators—repair or replace as necessaryTest temperature sensors and thermostats—calibrate and repair or replace as necessaryTest economizer dampers—repair or replace as necessaryTest main controller for performance: temperature setpoints and economizer cycle—calibrate and repair or replace as necessaryBalance zone and diffuser dampersAdditional insulation around door to the boiler room and exposed ductworkAs detailed above, this phase would consist of overhauling the existing system to optimize it’s performance, return the system to design flowrate conditions and take full advantage of the free- cooling economizer cycle. This phase would not solve the library’s thermal comfort issues in the hotter months, but should reduce the number of uncomfortable days and would improve thermal comfort in the heating season. The cost estimate used to calculate payback for this phase of the recommendation was $20,000. This included a quote of roughly $7000 for system inspection and balancing (Refer Appendix J) plus the replacement cost of economizer dampers and actuators of $6000 and an allowance for controls components and installation costs. This is obviously a rough estimate based on speculation of necessary repairs. The repair of the economizer cycle would qualify for an Energy Trust of Oregon (ETO) incentive (see Appendix F). The payback was calculated to be under 3 years (see Table 10).Phase 2: Digital Control RetrofitInstall hybrid digital control system using electronic-to-pneumatic (EPT) transducers to make use of pneumatic power but gain digital controlInstall EPT switches at 16 heating coils and 1 main hot water valveInstall EPT switches at 3 damper motorsInstall 16 digital thermostatsInstall main digital controller with 3 temp sensorsAs detailed above, this phase would involve implementing DDC controls while utilizing the pneumatic power system to save in first cost. It should be noted, however that if the pneumatic system is found to be faulty or costly to recondition, a full conversion to DDC (see Phase 4) would make more economic sense.The installed cost of this phase would be approximately $40,000 and would qualify for an ETO incentive. The calculated payback period of 8.5 years for DDC controls was based on the full conversion cost of $60,000 (see Table 10). This hybrid conversion, while not producing the same level of energy efficiency, would still have a payback of under 10 years.Phase 3: Install mechanical coolingInstall a chiller to accommodate the additional cooling needs. This will ensure that the library will meet its required cooling capacity and thermal comfort. For chiller selection, an air-cooled chiller is recommended over a water-cooled chiller. The reasons for selecting an air-cooled chiller were:Air-cooled chillers have a lower upfront cost compared to water-cooled chillers.Aesthetics of the building: Water-cooled chillers require a water cooling tower. The cooling capacity for the library requires a significantly large water tower that will be hard to conceal.Water-cooled chillers produce a visible plume of steam.A limited economic analysis was conducted on the two options of implementing the cooling coils. Cost estimates for the coils were obtained to compare each option. The quote from Greenheck listed the large coil as $18,000 and the 16 smaller coils as $32,000. It should be noted that these cost values do not include the cost of installation and maintenance. The cost of installing the coils, the extensive chilled water supply lines, the individual drain lines, and the individual control components for the individual coils was not estimated but considered to be a prohibitive first cost and more expensive than other more energy efficient measures. Individual coils also have an increased associated maintenance cost due to internal and external fouling. From our limited analysis, the use of one central cooling coil was determined to be the best cooling coil option.Determination of the proper size for the central cooling coil was influenced by several parameters. A cooling coil must be designed such that the face velocity does not exceed approximately 550 feet per minute with a maximum fin density of 11 fins per inch to avoid moisture carry over into the supply air. Also, the coil size was kept as small as possible to minimize first cost. A Greenheck coil sizing calculator was used to size different iterations of coils. The final design choice had a face area of 83.3 ft2 with a face velocity of 500 fpm and an overall size of 8’ x 10’. Design details as well as sample hand calculations are shown in Appendix H. The coil has a built in drain pan and can be drained into an existing floor drain in the adjacent room. The proposed locations for the central coil, chiller and chilled water piping are shown in Appendix D. To regulate zone temperatures using the central coil, a return and supply fan VFD and variable speed motors are recommended as well as automatic zone control dampers. This retrofit equipment will not only provide an energy efficient means of regulating the mechanical cooling but will improve energy efficiency of the mechanical system year-round. As energy saving measures, the VFD with motors and the zone dampers would qualify for ETO incentives. ETO requires that measures be assessed individually for qualification of incentives. The payback analysis of these measures (see Table 10) showed a payback of 11.3 years for the VFD and 3.1 years for the zone dampers. With a payback of over 10 years, the VFD would not qualify for an incentive. ETO might consider these items as one system since they are interdependent which would allow both to qualify.Phase 4: Complete DDC ConversionThis phase is an upgrade from Phase 2. Rather than having a hybrid control system using EPT, all the pneumatic controls and actuators will be replaced with a complete digital package. This full conversion will improve system control and reduce maintenance costs associated with a pneumatic system. At this time, DCV CO2 sensors should be installed to control outdoor air intake as well as humidistats (see Appendix J) in the zones with the most humidity fluctuation.The estimated cost of this phase is approximately $25,000 and would qualify for an ETO incentive. The calculated payback period of 8.5 years for DDC controls was based on the full conversion cost of $60,000 (see Table 10). This completion of the digital conversion would have a payback of under 10 years. The DCV portion of the overall cost was analyzed and found to have a payback of under 1 year.Below is the summary of four different design phases. Table SEQ Table \* ARABIC 9: Design phase summaryDesign AlternativesImplementationServiceControlsCoilsZone Volume ControlAlternative I:Complete Mechanical CoolingSystemSimultaneousExisting systemFull DDCLargeSingleVFD, Individual Dampers + DCV, HumidistatsAlternative II:MultiphaseInstallmentsPhase 1Existing system---Phase 2Existing systemHybrid Digital controls--Phase 3 Option 1-Hybrid or Full DDCLarge SingleReheat Option 2-Hybrid or Full DDCLarge SingleVFD, Individual Dampers Option 3-Hybrid or Full DDCMultipleIndividual DampersPhase 4-Full DDCLarge SingleVFD, Individual DampersTable SEQ Table \* ARABIC 10: Costs and simple paybacks of design optionsConclusionsThe recommendations for the system each have a different overall value which contributes to the thermal comfort of the library occupants. The goal of providing an increased lifespan for the books in the main stacks is also met by providing occupant comfort. These are all weighted in the design evaluation matrix (see Table 8). The chiller is the most critical element to improve thermal comfort in the summer season. Carrying out repairs for the economizer system will improve comfort and reduce the total energy consumed by the chiller. The volume control dampers will allow the system to compensate for discomfort in individual zones with minimal changes to the ducting plan as a whole. This will also reduce the need for reheat to compensate for over-cooling. Volume control dampers require variable speed fans. While not justified on their own, the sum of the components will be a net improvement. Direct digital control (DDC) will improve the operating efficiency of the overall system by allowing precise temperature setpoints and throttling. The addition of demand control ventilation (DCV) lets the system reduce zone ventilation when there are no occupants in a given zone. The DCV will prevent zones from being over conditioned for occupants that are not present. Humidistats in problem zones will improve humidity fluctuations in winter months. Changes to the envelope are purely to decrease the thermal loads in some zones in order to reduce the energy requirement for the HVAC. Overall, recommended measures improve energy efficiency and have a reasonable payback.References[1] 2009 ASHRAE Handbook Fundamentals. Atlanta, GA: American Society of Heating, Refrigeration and Air-Conditioning Engineers, 2009.[2] Principles of Heating, Ventilating and Air Conditioning. 6th Edition. Atlanta, GA: American Society of Heating, Refrigeration and Air-Conditioning Engineers, 2009.[3] U.S Energy Information Administration. Buildings Energy Data Book: 2003. Accessed February 2012. [4] Tobias, Leanne, and George Vavaroutsos, et al, Retrofitting Office Buildings to Be Green and Energy-Efficient: Optimizing Building Performance, Tenet Satisfaction, and Financial Return. Washington, D.C.: Urban Land Institute, 2009.[5] RSMeans, Building Construction Cost Data: The 2012 Building Construction Cost Data, 70th Annual Edition, RSMeans, A Division of Reed Construction Data. (Norwell, MA, 2012).[6] Amrit B. Marathe, Oct-Dec 2002Air conditioning and Refrigeration Journal, Selecting Cooling Coils with Proprietary Software[7] Greenheck Software Coil Modeling & Calculations. [8] A. Bhatia, Selection Tips for Air Conditioning Systems. [9] Herbert W. Stanford III, HVAC Water Chillers and Cooling Towers. Fundamentals, Application, and Operation. Dekker 2003.AppendicesAppendix A :Appendix B :Appendix C :Table C : Hourly BIN data collected at Mt.Angel Library Jan,15th 2012 – May,14th 2012MezzanineCatalog RoomAuditorium1st Floor StacksCarrelBins (deg F)160-10153-1Library-1153-3153-8Below 600000060-65001120065-70298157015761411144870-752461121510811419133975-80835968145480-854564585 and up66566Appendix D:Figure D-1 : Cooling Coil Placement Figure D-2: Chilled Water Pipeline Model RunNatural Gas (BTU);Domestic Hot WaterZone HeatTotal GasElectric (kWh)Area LightingMisc. EquipmentPumps & Aux. SystemsVentilation FansSpace CoolingTotal electricCurrent System745000006878200000695270000019225037660294001274900386800Variable Frequency Drive74500000696560000070401000001922503766029400612300320540Demand Control Ventilation74500000639020000064647000001922503766029400713600330670Zone Control Dampers75000000626080000063358000001922503766030990612300322130Chiller Only74700000802370000080984000001922503766051730185170182250649060Economizer74700000737520000074499000001922503766050940185100154140620090Full Upgrade74700000737000000074447000001922503766049870185100119360584240Appendix E:Table E-1 : Industry Cost Estimates Table E-2 : Simulated Energy Consumptions by Component Appendix F:Energy Efficiency IncentivesAs a customer of Portland General Electric (PGE) and NW Natural Gas, energy-efficient improvement cash incentives are available to Mt. Angel Abbey for the addition of cooling to the library through Energy Trust of Oregon (ETO). Incentives are generally available for projects that can show a maximum of 10 year payback (9 years for gas). The incentive is based on annual energy savings as well as any annual non-energy savings such as maintenance and water use. The incentive is calculated based on $0.25/kW-hr or $1/therm of energy saved plus non-energy savings and is limited to 50% of the project cost including installation. The energy savings are based on a comparison to baseline (existing) conditions. In the case where baseline is a nonexistent system (such as with the library’s chiller) the incentive is based on energy savings above the minimum code required energy efficiency rating. ETO incentives are calculated on a measure-by-measure basis. For the library, available incentives would include:Chiller: energy savings above minimum code requirement; cost based on difference in base model and more efficient modelRepair of economizer: energy savings from fully functioning economizer applied to cost of repair and replacementVFD: energy savings from installation of VFD applied to cost of parts and installationDDC: energy savings from installation of digital controls applied to cost of parts and installationEnergy savings are typically calculated based on simulations of system enhancements using a building energy model.Table F : Payback and ETO IncentivesAppendix G:Table G : Comparison Between Air-Cooled & Water-Cooled ChillersAir-Cooled ChillersWater-Cooled ChillersCostAir-cooled chillers that don’t use water condenser pumps have lower initial costs.Higher initial costs due to using water cooling towers. However, the lower condensing temperature of this type of chillers can offset the higher initial cost.Energy efficiencyConsume 10% more energy that water-cooled chillers. Since water transfers heat more efficiently than dry surfaces.Have higher efficiency than air-cooled chillers.CapacityLimited to 500 tons of capacity.Have capacity up to 3000 tons.MaintenanceLess and limited maintenance operations needed.More maintenance needed such as water treatment, cooling tower services, and freeze protection.AvailabilityQuicker availability since this type of chillers uses air as the cooling mediumMust have water source available and cooling tower installed.Appendix H:Hand calculation steps and equations: (3. A. Bhatia, )These equations provide the framework to be able to calculate the necessary information to be given to Greenheck for cost breakdowns. Face VelocityFace Velocityfpm=Dehumidified Air Flow(cfm)Face Area (ft2)Number of rows required Number of rows required=Tons × 12000U × LMTD × Face Area × Outside Face Area per Face Area per RowWhere: LMTD= Log (to the base) mean temperature difference.U= overall heat transfer coefficient (Btu/ hr.sqft.F.row)Ton=Capacity × 100012000LMTD=GTD-LTDLoge GTDLTDWhere: GTD= DBmix- LWT LTD= DBair- EWT1∪=1Ko+ rm+ RKiTable H : Outside film coefficient (for dry coil)Coil face velocity (fpm)?Ko (Btu/hr.sqft.F)100?4.1200?6.3300?8400?9.6500?11600?12.3Water flow Water Flow US gpm=Tons × 12000500 × (LWT-EWT)Sample Calculation for cooling coil number 2:Given:Leaving water temp. (°F)= LWT= 78Entering water temp. (°F)= EWT=58Face area = 11 ft2Leaving air temp. (°F)= DBair=65.9Capacity = 166.7 MBHFluid velocity = 2.60 ftsActual air flow = 5525.658 cfmMetal resistance (( hr.sqft.F) per Btu)= rm= 0.025Outside surface area (sqft./row/face area)= R=22Solution:Face Velocity (fpm) =Dehumidified air flow cfmFace area sq.ft.= 5525.65811=502.33 No. of rows required =Tons ×12000∪ ×LMTD ×face area ×Outside surface area per face area per rowWhere: Tons=Capacity ×10001200=166.7 ×100012000=13.8917 1∪=1Ko+ rm+ RKi We have to do iteration using table H 1 and 2 to get Ko and Ki 502.3-500X-11=600-50012.3-11 >>>>>Ko=11.0307 Ki=490 1∪=111.0307+ 0.025+ 22490 = U= 6.5358 LMTD=7-7.9Loge 77.9 = 17.133 So,No. of rows required=13.8917 ×120006.5358 ×17.133 ×11 ×22=6.1513Water flow (US gpm) =Ton ×12000500 ×(LWT-EWT) = 13.8917 ×12000500 ×( 78-58)=16.6692Hand calculations based on above formula’s:Coil Nameface area (ft^2)Capacity ( MBH)# of rowswater flow(usgpm)Central Cooling Coil83.3161712.6161.7111166.76.116.67211166.76.116.673348.66.44.864352.711.85.275347.76.44.7760.8613.17.11.317354.710.45.4781.528.611.42.8692.7847.9104.79101.528.711.82.87112.8951.311.35.13127115.56.411.551311164.66.116.46141.7526.66.22.66152.543.57.94.351615.13247.16.424.71Greenheck Cooling Software – Coil selectionThe Greenheck software was used in conjunction with our hand calculations that resulting in a cooling coil design and file that were used to determine the cost of each coil. The files for each coil were provided to the Greenheck Company for unit pricing. The chart below has the cost for each cooling coil configuration specified:Coil Name CostTotal Cost of coils 1 to 16 cost of one large coilCentral Cooling Coil $18,118 $32,906 $18,118.00 1$3,265 ??2$3,265 ??3$1,431 ??4$1,917 ??5$1,431 ??6$963 ??7$1,856 ??8$1,236 ??9$1,672 ??10$1,236 ??11$1,915 ??12$2,441 ??13$3,432 ??14$1,087 ??15$1,352 ??16$4,407 ??Appendix ICAP CFMTemp inTemp outCoil CAP Btu/hrHC1896061.683.8-214824.96HC2896061.683.8-214824.96HC3260061.677.3-44085.60HC4243061.691.1-77419.80HC5254061.675-36758.88HC670061.674.4-9676.80HC7260061.684.4-64022.40HC8136061.691-43182.72HC9225061.685.1-57105.00HC10137061.6100.5-57556.44HC11235061.6124.2-158878.80HC12613061.674.5-85403.16HC13900061.674.7-127332.00HC14142061.686-37419.84HC15221061.687.3-61340.76HC161337061.681.3-284460.12Appendix JJune 8, 2012John SlateReference:Mount Angel Abbey Library Pneumatic Controls Service/RepairsDear John,The following proposal is for the above referenced project and is based on information received from our recent correspondence and your RFP dated 5/17/12.We are offering pricing to service and calibrate the existing pneumatic controls serving the mechanical equipment in the Library. If we find that there are significant repairs, we will identify that in a follow-up proposal and scope letter. Please review scope of work below. Scope of WorkVerify operation of existing air compressor and run times (to help to determine if there are leaks in the piping) Check operation of AHU and fans, belts and grease bearings.Verify operation of boiler and pumps.Change oil and intake filter to air compressor.Verify if contaminants are present in control air piping, i.e. water and oil. Calibrate and note condition of (16) zone thermostats.Verify operation of (16) hot water control valves.Verify operation of return, exhaust and OSA dampers and actuators. Calibrate return, exhaust and OSA temperature sensors. Check operation of receiver controllers, low limit controller and minimum position control in main controls panel.Verify operation of existing electric/pneumatic switches and pneumatic/electric switches.Visually check and listen for air leaks and make minor repairs ExclusionsOvertime or after hours work.Replacement components.Verifying operation of smoke sensor and smoke dampers. While we could include an allowance for this, we could not verify the quantity and location.Price Installed$ 6,836.00Note: Without seeing the mechanical room and being familiar with the site, we have included a time allowance to verify location of all devices and trace out the pneumatic lines.If you have any questions with the above information please don’t hesitate to contact us. My direct line is (503) 417-0346. Sincerely,Brian SchainProject ManagerFigure J. Quote for service and inspection of pneumatics and dampers.[Brian Schain (Project Manager, Plumbing and Mechanical Contractors Group), In response to RFP, June 2012]Appendix KBy observing the information collected from the data loggers that were placed in the library, it can be seen that during the winter, the humidity levels have a significant fluctuation. The humidity rises above the desired 50% RH level. In order to address this issue, humidistats should be installed. These electronically controlled units will adjust the outside air mixture and override the cooling coil set points. From the psychometric chart analysis for cooling seasons (refer to the Psychometric chart below), it can be seen that there is a need for additional humidity if maintaining 50%RH is desired. According to ASHRAE data (Appendix B, Lifetime Multipliers Relative to 68°F and 50% RH) for library books, below 50% RH is acceptable. Because of this, having lower humidity levels during summer is not a critical concern for the Mt.Angel library. ................
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