Table of Contents Page Number(s) Executive Summary 2 Project Background 3 Proposed Depth Alternatives 4 Proposed Depth Redesign 5-7 Justification of Proposed Depth Redesign 8 Proposed Breath Redesign 9 Integration and Coordination 9 Proposed Solution Method 10-11 Difficulties and Limitations 11 Research and References 12 Appendix A Heating and Cooling Loads 13 Appendix B Electric Utility Rates 13 12/05/02 1
THESIS PROPOSAL Executive Summary Centre Community Hospital East Wing Addition is a 3 story 50,000 square foot addition to the existing Centre Community Hospital that will house 12 Intensive Care Units, Same Day Surgery Units, administrative offices, an auditorium, and a cardiovascular rehabilitation room. The existing mechanical systems consist of nine direct expansion air handling units accompanied by air cooled condensers. Two boilers provide hot water for preheating coils in the air handlers and for the heating in the terminal hot water duct heaters. The focus of this proposal will be the mechanical systems in the Intensive Care Units and Same Day Surgery Units located on the 15,000 square foot first floor. Radiant heating and cooling from suspended ceiling panels will be utilized in parallel with 100% outdoor air units for fresh air requirements. This design will require the addition of two chillers and two air handling units equipped with glycol runaround heat recovery loops. The goal of this thesis will be to improve the indoor air quality of these spaces and to show a savings in energy by the implementation of this type of system. Space savings and a reduction of congestion in the plenums will also be analyzed. Electrical systems will be affected by this radiant heating and cooling system, and it will be redesigned accordingly. Circuit breakers, circuits, panel boards, and overall power usage will be calculated and analyzed as a part of this thesis. The placement of mechanical equipment on the roof will affect the size of the structural members supporting these pieces of equipment. A structural analysis and redesign will be incorporated if the size and weights of the new units deem necessary. The entire process of this thesis has been broken down into eight major categories. A workable timetable of thirteen weeks has been developed to complete this thesis on time. Research of topics that pertain to all aspects of this thesis has been conducted and will continue to be as this process goes on. 12/05/02 2
Project Background Centre Community Hospital (CCH) East Wing Addition is a three story, 50,000 square foot building that performs many functions for CCH s overall hospital operations. The basement floor contains medical records, a cardiovascular rehabilitation room, mechanical spaces, and electrical spaces. The ground floor contains administrative offices, an executive board room, and an auditorium. Occupying the first floor addition are 12 Intensive Care Units (including two pressure isolation rooms) and Same Day Surgery Units. All spaces in this addition are conditioned by nine constant volume, direct expansion air handlers. AHU 69 and 70 are 100% outdoor air units that serve the patient areas with a glycol runaround loop for heat recovery. Heat for the vapor compression process is rejected through the use of air cooled condensers located in close proximity to the air handler that it is associated with. (See Appendix A for building heating and cooling loads). Heating for the spaces is accomplished by using hot water preheat coils in the air handlers accompanied with terminal hot water duct heaters. Hot water needed for this process is provided by two 225 horsepower boilers located in the existing boiler house. The boilers provide 60 psi steam which is run through a heat exchanger to provide 180 degree water. All major mechanical equipment is located in three areas, on the roof, in the ground floor mechanical space, and in the basement mechanical room. Two vertical shafts, one in the southeast corner and another in the eastern part of the addition, allow for the run of ducts, pipes, and risers for the entire East Wing. The electrical systems in the East Wing Addition are more complicated than they would be in a typical building. Six major branches of power are provided including a normal branch, a life safety branch, a critical branch, an emergency only branch, an emergency equipment branch, and an uninterrupted power supply (UPS) branch. The life safety, critical, and UPS branches are fed from the existing electrical systems in the hospital. The new 480 V, 2500 A service provides power for the normal, emergency only, and emergency equipment branches. This service is backed up by a 500 KW diesel generator located in the basement of the East Wing. (See Appendix B for CCH s Utilities Rates) 12/05/02 3
Proposed Depth Alternatives Proposal Alternative #1 Under Floor Air Distribution Problem Statement: The 4136 square foot, 200 person capacity auditorium located on the ground floor is supplied with air by linear ceiling diffusers. There are also hard wired computer and electrical circuits that must be supplied to each seat. Problem Solution: Use an under floor air distribution system to provide airflow underneath the seats and to make installation and relocation of computer and electrical circuit easier. The under floor air distribution will improve the comfort level in the space, and it will also raise the supply air temperature, thus saving energy. Proposal Alternative # 2 Chilled Water Problem Statement: All nine air handlers are direct expansion (DX) with air cooled condensers. This is an energy intensive way to condition a building. Problem Solution: Use a chiller to provide cooling for each air handler, and use cooling towers for heat rejection. This system will save energy compared to the DX system and also could provide first cost savings. Proposal Alternative # 3 Radiant Heating and Cooling in Parallel with 100% Outdoor Air AHU s Problem Statement: All nine air handlers are direct expansion with air cooled condensers. This is an energy intensive way to condition a building. Problem Solution: Use a radiant heating and cooling panel system in all spaces except for the auditorium. This will require the addition of chillers and cooling towers. This system will improve the indoor air quality of the building and reduce the energy consumption of the mechanical systems. Proposal Alternative # 4 Radiant Heating and Cooling in Parallel with 100% Outdoor Air AHU s Problem Statement: All nine air handlers are direct expansion with air cooled condensers. This is an energy intensive way to condition a building. Problem Solution: Same as Alternative # 3 except the radiant heating and cooling will be used only on the first floor, where all of the patient areas are located. 12/05/02 4
Proposed Depth Redesign The proposed redesign will be the utilization of radiant heating and cooling panels in parallel with 100% outdoor air AHU s in all spaces on the first floor of the 15,000 square foot East Wing Expansion. The first floor is where all the patient areas, therefore critical mechanical spaces, are located. 12/05/02 5
The radiant heating and cooling suspended panels (Figure 2) will be a four pipe system (Figure 1) allowing for heating or cooling of any space, at any given time. The 100% outdoor air units will supply only the amount of outdoor air required for acceptable indoor air quality to the spaces. A conventional HVAC system would supply the amount of outdoor air needed along with conditioned return air to meet the space loads. In this system the majority of the space load will be met with the radiant heating and cooling panels, with the conditioned outdoor air taking care of the rest of the load that is remaining. Figure 1 4 Pipe Arrangement ASHRAE HVAC Systems and Equipment Figure 2 Suspended Radiant Panel ASHRAE HVAC Systems and Equipment This system will replace three direct expansion, constant volume air handlers along with their air cooled condensers. The two existing 225 horsepower boilers will remain, although the hot water produced will be used in radiant ceiling panels instead of the existing terminal hot water duct heaters. A new chiller will be required to produce the chilled water needed for the radiant cooling panels. The Intensive Care Units and the Same Day Surgery Units require N + 1 redundancy therefore a second chiller, the same capacity as the first, will also be required. These chillers will be placed in the mechanical room located in the basement. Two new 100% outdoor air handlers will be required for this redesign. The first floor requires N + 1 redundancy, therefore two air handlers will be used for this floor. These air handlers will be equipped with an ethylene glycol runaround loop (Figure 3) for heat recover from the exhaust air ducts, located in the southeast corner of the building. Figure 3 Glycol Runaround Loop Due to the reduction of air supplied to each space the supply and return ductwork will be resized, and the layout will be changed. The existing supply air diffusers will have to be replaced with high aspiration diffusers to distribute the fresh air properly. A ceiling plan of the redesign will be provided to show the savings of space and congestion. 12/05/02 6
Each room will be controlled by a space thermostat located on a wall that is not adjacent to the outdoors. The thermostat will regulate a three way valve (Figure 1, V-1) located before the panels that will provided heating or cooling, whichever is called for. A first cost mechanical comparison will be calculated for the proposed design. Equipment cost will be straight forward, but labor and installation cost will have to be estimated. Installation costs of radiant panels may be difficult to find, but an educated estimate can be determined. The cost of placing less equipment on the roof will also be taken into consideration, along with the cost savings of relocating the equipment for the building s future expansion. Energy savings and operational cost will be covered in the breath analysis. Example of 100% OA air handlers to be used Example of cooling towers to be used Example of water cooled chillers to be used Courtesy of Trane Courtesy of Marley Cooling Towers Courtesy of the Carrier Corporation 12/05/02 7
Justification of Proposed Depth Redesign This proposed radiant heating and cooling system has been used effectively in many applications, including health care facilities, in Europe over the past years. It provides numerous beneficial factors to a building s overall operation. The most beneficial effect it will have on this building is the comfort level and indoor air quality that it will provide. The area in which this system will be installed is the Intensive Care Units and Same Day Surgery Units. The patients in these areas are very sensitive to temperature variations and airflow, and this system will greatly enhance their comfort level. A conventional HVAC system would satisfy all heating and cooling loads using air supplied to the space. This system will produce drafts and air movements that may be very unpleasant to patients. Since there will be very little air movement compared to a conventional HVAC system, the proposed solution will greatly reduce airborne contaminants. This is a very critical issue in the patient care areas. This system will reduce the chances the other patients and medical staff from receiving airborne diseases from others. Another beneficial factor is that this system will reduce the mechanical operational cost. Less air will have to be conditioned due to the fact the ceiling panels are removing most of the load, which will save energy. Since less air is being supplied to the space and the ductwork layout is simplified, energy use of the fans will be reduced. When using radiant panels the perceived room temperature is lower than the air temperature, which allows for higher temperature then normal air to be supplied, hence saving energy. Ductwork will be able to be downsized considerably due to less airflow being supplied. Not only will this save money for materials and labor, but it will make the plenum area less congested. The terminal hot water duct heaters and the piping serving them will be able to be removed, freeing up even more space in the plenum. A major beneficial factor that may not be that noticeable is that three air cooled condensers and one air handler will be removed from the roof. The equipment on the roof would not be a problem in a typical building, but this building has been designed for two more stories to be added above the first floor. The structure, electrical systems, and mechanical risers are all designed for this soon to be addition. It will be very beneficial to keep as much equipment off the roof as possible to prevent it from being moved in the future. My proposed design would only consist of two air handlers being placed on the roof. The chillers will be located in the basement mechanical room and the cooling towers will be placed in the ground floor stilt space. This proposed solution will also have educational value. Even though this system would never be approved by the building engineer, this gained knowledge of radiant systems will be beneficial in the future. Although many engineers and owners would frown at the ideas of using radiant heating and cooling, I believe that once this systems begins to be implemented it will cause a snowball effect in the HVAC industry. 12/05/02 8
Proposed Breath Redesign Electrical The proposed mechanical system will have a drastic change in the power consumption of the building. New power requirements will come from the chillers, cooling towers, air handlers, pumps, and fans. All of these new feeds will be sized for their power consumptions and rerouted into different panels. The new wire sizes, circuit breakers sizes, and currents will be calculated for each new piece of mechanical equipment. Power consumption of the new equipment will be less then the consumption of the existing equipment for the first floor. The proposed consumption will be calculated and compared to the existing conditions. Kilowatt and kilowatt-hour usage will be calculated, thus an overall cost savings will be able to be shown. It will be determined if any of the existing panels boards or services will be able to be downsized due to the reduced load. Structural Two new air handlers will need to be placed on the roof. The proposed location is where AHU 69 and 70 are currently located. It has yet to be determined if these units are heavier then AHU 69 and 70. If the new units are heavier, which would be a good assumption, then the structural support of the roof will have to be analyzed. If the structural support is not sufficient for these units, the associated structural members will have to be resized. Integration and Coordination This proposed solution will be easily integrated and coordinated into the existing architectural design. One possible problem may be the placement of the chillers. The proposed location in the basement mechanical space is not very congested, therefore rearranging of existing equipment should allow room for the chillers. Clearance requirements for all equipment in this room will have to be verified. The cooling towers will be able to be placed in the area on the ground floor behind existing air cooled condensers 63, 64, and 65. The two new air handlers will be able to be placed on the roof where AHU 69 and 70 currently exist, although structural support for these units will need to be verified. Integration and coordination of the plenum space becomes simplified due to this system. Ductwork will become smaller and less of it will be required. Hot water supply and return piping for the hot water duct heaters will be removed, along with the duct heaters themselves. Space in the plenum will no longer be an issue. It is estimated that up to 12 of plenum space can be saved. This type of systems makes it extremely easy for medical gas piping, sprinkler piping, and light fixtures to be laid out and installed. 12/05/02 9
Proposed Solution Method A. Panel Cooling Weeks 1 and 2 1. Establish design indoor design conditions. 2. Calculate sensible and latent cooling loads and heating loads for spaces. Carrier s Hourly Analysis Program 4.1 will be used to determine these loads. 3. Select mean water temperature 4. Determine the amount of outdoor air required in all spaces for the third floor. Table 7.2 from AIA Guidelines for Design and Construction of Hospital and Health Care Facilities, 2001 Edition will be used. Spaces not in this table will be designed in accordance with ASHRAE Standard 62, Ventilation for Acceptable Indoor Air Quality, 2001 Edition. 5. Calculate latent cooling available from outdoor air 6. Calculate sensible cooling from outdoor air 7. Select a panel and determine its cooling load 8. Determine the panel area necessary from the reaming cooling 9. Design the panel layout B. Panel Heating Weeks 3 and 4 1. Establish design indoor design conditions. 2. Calculate room heat loss 3. Select mean water temperature for the water 4. Determine surface temperatures of unheated surfaces t u = t a U/h * (t a t o ) 5. Determine AUST of surfaces in room 6. Determine surface temperature of heated radiant surface Refer to figure 9 and 10 of ASHRAE Systems and Equipment chapter 6 7. Determine the panel area necessary for heating Refer to figure 9 and 10 of ASHRAE Systems and Equipment chapter 6 8. Design the panel layout C. Ductwork and Diffuser Layout Week 5 1. Determine the number of diffusers per space 2. Layout and size supply and return ductwork Use ductulator to size 3. Put ductwork layout into CAD to show the space savings in the plenum D. Equipment Selection Weeks 6 and 7 1. Select and size chillers, air handlers, cooling towers, glycol runaround loops, pumps, and fans E. Structural Analysis Week 8 1. Resizing of structural support for new air handlers if necessary 12/05/02 10
F. Electrical Week 9 1. Size circuits and circuit breakers for all mechanical equipment 2. Place the equipment on panel boards G. Cost Analysis Weeks 10 and 11 1. Determine the mechanical first cost savings 2. Determine the installation and future relocation of equipment costs. 3. Determine and calculate the KH and KWH usage 4. Determine the operational cost on a KWH basis 5. Compare the savings of using radiant heating and cooling vs. the existing system H. Prepare Thesis Presentation Weeks 12 and 13 Difficulties and Limitations A proposal for radiant heating and cooling for the entire building would have been more realistic, but due to time restraints only the first floor will be redesigned. The overall cost savings will be deflated due to the fact that this systems is being implemented in such a small area of the building and due to the fact that N + 1 redundancy is required for the entire first floor. Difficulties in this design will be to keep the space conditions at a point where condensation will not occur during cooling operations. This problem can be solved using various sensors and careful design. This design should be somewhat straight forward and any difficulties or limitations will be proper handled if they occur. Enough examples of this type of system in medical facilities exists, therefore any problems or issues can be referenced to these examples. 12/05/02 11
Research and References AIA Guidelines for Design and Construction of Hospital and Health Care Facilities. 7.31 and 7.32 Mechanical and Electrical Standards for a General Hospital. American Society for Hospital Engineering of the American Hospital Association. Mechanical Systems, Volume 8. ASHRAE Handbook. HVAC Systems and Equipment 1996. Chapter 6, Panel Heating and Cooling. ASHRAE Handbook. HVAC Applications 1995. Chapter 7, Health Care Facilities. ASHRAE Standard 62. Ventilation for Acceptable Indoor Air Quality. 2001 Designing Dedicated Outdoor Air Treatment and Ventilation Systems. www.trane.com/commercial/equipment/sys-eb-3-01.asp. Mumma, Stanley. Ceiling Radiant Cooling Panels As A Viable Distributed Parallel Sensible Cooling Technology Integrated With Dedicated Outdoor-Air Systems. ASHRAE Transactions, May 2001. Mumma, Stanley. Overview Of Integrating Dedicated Outdoor Air Systems With Parallel Terminal Systems. ASHRAE Transactions, May 2001 Mumma, Stanley. Safety and Comfort Using Using DOAS Radiant Cooling Panel Systems. ASHRAE IAQ Applications Newsletter, 2001. Mumma, Stanley. Ceiling Panel Cooling Systems. ASHRAE Journal, November 2001. Solray - Radiant Heating Panels. www.solray.co.uk/main.htm Zent-Frenger Building Service Consultancy. Chilled Ceilings Operation and Function. * More references will be used as thesis process evolves 12/05/02 12
Appendix A Appendix B 12/05/02 13