Hvac System


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A short Brief on HVAC system

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Hvac System

  1. 1. 1 HVAC : Heating, Ventilating, and Air Conditioning (HVAC) equipment perform heating and/or cooling for residential, commercial or industrial buildings. The HVAC system may also be responsible for providing fresh outdoor air to dilute interior airborne contaminants such as odors from occupants, volatile organic compounds (VOC’s) emitted from interior furnishings, chemicals used for cleaning, etc. A properly designed system will provide a comfortable indoor environment year round when properly maintained. What can HVAC do? HVAC system performs four basic functions: 1. Control airborne particles, dust and micro-organisms – Thru air filtration using high efficiency particulate air (HEPA) filters. 2. Maintain room pressure (delta P) – Areas that must remain “cleaner” than surrounding areas must be kept under a “positive” pressurization, meaning that air flow must be from the “cleaner” area towards the adjoining space (through doors or other openings) to reduce the chance of airborne contamination. This is achieved by the HVAC system providing more air into the “cleaner” space than is mechanically removed from that same space. 3. Maintain space moisture (Relative Humidity) – Humidity is controlled by cooling air to dew point temperatures or by using desiccant dehumidifiers. Humidity can affect the efficacy and stability of drugs and is sometimes important to effectively mould the tablets. 4. Maintain space temperature - Temperature can affect production directly or indirectly by fostering the growth of microbial contaminants on workers. Each of above parameter is controlled and evaluated in light of its potential to impact product quality.
  2. 2. 2 What HVAC can’t do? 1. HVAC cannot clean up the surfaces of a contaminated surfaces, room or equipment. 2. HVAC cannot compensate for workers who do not follow procedures. We will learn about the specific design aspects later in this course, but first we will briefly discuss the generic pharmaceutical process. Pharmaceutical Process The task of the pharmaceutical manufacturer is to combine the medicinally active agents provided by a fine chemicals plant, or by extraction from vegetable, animal or other source, with suitable inactive ingredients so that the end product may be used in the correct dosage to produce the effect needed. What are advantages here? 1. Usually less air filter loading = lower filter maintenance and energy cost 2. Opportunity for better air filtration 3. Less challenge to HVAC = better control of parameters (T, RH, etc) 4. Less throw-away air = lower cooling/heating cost Disadvantages 1. Return air ductwork routing to air handler may complicate above ceiling 2. Chance of cross contamination = requires adequate supply air filtration (an sometimes return air filtration) Applications 1. Classified spaces such as sterile manufacture (few airborne materials, very clean return air) 2. Finished oral solid dosage (OSD) manufacture where product is not airborne with other products in the facility 3. Final bulk APIs, usually with dedicated air handler for each room .
  3. 3. 3 Comfort Requirement: � Temperature � Humidity � Air movement � Fresh air � Clean air � Noise levels � Lighting � Furniture and work surfaces A comfortable environment, however, is broader than just temperature and humidity. Comfort requirements that are typically impacted by the HVAC system include: • Dry-bulb temperature • Humidity • Air movement • Fresh air • Cleanliness of the air • Noise levels Some HVAC systems address these comfort requirements better than others. In addition, there are other factors that affect comfort but are not directly related to the HVAC system. Examples include adequate lighting, and proper furniture and work surface.
  4. 4. 4 A-V Stages of HVAC sys: A. Design Conditions: Following are the temperature/humidity conditions to be used for the design of HVAC systems that serve “standard” buildings/spaces: Outdoor Air: 94 Degrees F. DB / 76 Degrees F. WB for cooling 79 Degrees F. WB for evaporative cooling -10 Degrees F. DB for heating Indoor Air: 75 Degrees F. DB / 50% RH for cooling 70 Degrees F. DB for heating When a system that serves a “standard” building/space is provided with positive humidity control, the space humidity setpoint shall be limited as follows: Summer: Not less than 50% RH Winter: Not more than 30% RH Examples of “nonstandard” spaces are central computer rooms, library rare book rooms, animal facilities and laboratories with special temperature/humidity requirements. In order to maintain a space relative humidity outside these limits specialized HVAC equipment and/or building construction is required. B. Central Utilities: HVAC systems shall utilize central distributed chilled water, central distributed steam and central distributed electricity whenever these utilities are available. Lower pressure “Campus steam”, if available, (as opposed to higher pressure “Utility Steam”) shall be used as the source of heat for all HVAC systems within campus buildings that are served with steam from Abbott Power Plant through the central steam distribution system. If “Campus Steam” is not available (e.g. at more remote locations such as the Veterinary Medicine Complex and the furthest north reaches of campus) then “Utility Steam” may be utilized to serve building HVAC systems. The dedicated utilities that serve a new building (or portion thereof) shall be sized and configured as appropriate to serve potential load growth.
  5. 5. 5 C. Central HVAC Systems: Each building shall be served by a minimal number of central HVAC systems rather than numerous individual/package units such as fan coil units, window air conditioning units or DX “split systems”. Typically, each central system shall include an air handling unit, a return and/or exhaust fan or fans and air distribution/return/exhaust ductwork. D. Institutional Quality: HVAC equipment/systems shall be institutional as opposed to commercial grade (i.e. having a 25 year minimum life expectancy for dynamic system components such as motors, switches, pumps, valves, fans, dampers, compressors and burners, and a 50 year minimum life expectancy for static system components such as ductwork, piping, conduit, and wiring). E. System Size: The number of small systems (i.e. less than 5,000 CFM) shall be minimized. The installation of a smaller number of larger systems typically results in higher equipment quality and reduced maintenance requirements while providing more opportunity for the application of energy conserving features and control strategies. F. System Configuration: HVAC systems shall be configured such that spaces with similar usage are served by a common system. As much as possible, spaces with dissimilar usage types or schedules shall not be served by the same system. Large lecture halls / public assembly areas shall be served by a dedicated HVAC system. The animal facilities within a laboratory building shall be served by a dedicated HVAC system. Areas that have special temperature and/or humidity requirements shall be served by dedicated systems. This allows the design of each system to be tailored to the specific needs of the areas being served. It also allows the implementation of specific control strategies (such as occupied/unoccupied modes and temperature resetting) for each system to conserve energy while satisfying the requirements of all of the spaces served by that system. G. Future Requirements: Each HVAC system shall be sized and configured so as to accommodate anticipated/potential changes in loads, layout, etc. (within practical limitations) as the use of the areas served changes in the future.
  6. 6. 6 H. Backup Equipment: A 100% backup or duplex unit shall be provided for each critical piece of HVAC equipment that is vulnerable to failure. I. Equipment Location: Each piece of motorized HVAC equipment shall be located within a mechanical equipment room with the exception of roof mounted exhaust fans, window air conditioners and specialized unitary equipment such as “Liebert” computer room units that are specifically designed to be located within the space being served. Location of motorized HVAC equipment above finished ceilings shall be avoided. J. Energy Conservation. K. Sound Control: Sound control as it relates HVAC systems shall be given adequate priority. As mentioned elsewhere, the best way to control noise is to not create it in the first place. When focused attention is given to maximizing the efficiency of HVAC systems, noise is much less of an issue. The allowable HVAC-related background noise level for a given type of occupancy shall not exceed the guideline criteria . L. Vibration Control: Most floor supported rotating HVAC equipment that is located within the lowest level of a building , with the exception of air distribution equipment and reciprocating equipment (e.g. air/refrigeration compressors and internal combustion engines) may and shall be installed with virtually no special provisions for vibration isolation between the equipment and its support system or associated hydronic piping. This equipment shall typically be “hard mounted” directly to a reinforced concrete housekeeping pad without the use of vibration isolation devices and “hard connected” to the piping systems they serve without the use of flexible pipe connectors. The use of flexible pipe connectors shall be minimized since they have proven to be leak/failure prone. An exception to these general rules may be necessary in facilities where equipment that is especially vibration sensitive (e.g. an electron microscope) is located at the lowest level of the building in close proximity to an equipment area. Rotating HVAC equipment that is supported from any ceiling or supported by any floor other than the lowest floor of the building shall be individually evaluated to determine if vibration isolation devices, inertia bases and/or flexible pipe connectors are needed to prevent unacceptable levels of vibration from being transmitted into the building structures. M. Terminal Zoning: HVAC systems shall be configured such that each occupied space can be controlled as a separate zone with regard to temperature and/or
  7. 7. 7 airflow. In other words, one terminal control unit (e.g. constant volume reheat coil or VAV unit with reheat coil) shall be provided for each occupied space. N. Multi zone Units: When a multi zone air handling unit is utilized it shall be configured such that 100% of the airstream passes through the cooling coil prior to entering the reheat coil / bypass area in order to provide adequate humidity control. O. Fan Coil Units: Fan coil units shall not be installed, except as a last resort when it is not possible to serve an area by means of one or more central air distribution systems. In those instances where heating/cooling fan coil units are installed, they shall be “four pipe” units. P. Disallowed Equipment: The following types of HVAC equipment/systems shall not be installed in campus facilities: 1. “Rooftop” or similar packaged heating and/or cooling units 2. Residential furnaces / air conditioning systems 3. Heat pump type heating/cooling units 4. “Two-pipe” combination hydronic heating/cooling systems Q. Control Systems: (See the Energy Management / Environmental Control Systems section within these General Guidelines for specific control system guidelines and requirements.) R. Freeze Protection: Water, steam and condensate piping systems shall not be installed in locations where they could potentially become vulnerable to freezing (e.g. outdoors without sufficient earth cover, within unheated spaces, within building exterior walls or wall cavities, within exposed overhangs, within exposed exterior walkways, etc.) S. Humidification: Space humidification shall be avoided as much as possible due to the energy and maintenance costs as well as the indoor air quality problems associated with it. When required, it typically be provided by means of a steam reboiler type humidifier installed at the central station air handling unit that serves
  8. 8. 8 the area to be humidified. The makeup water to each humidifier shall be softened to reduce scaling within the humidifier. Steam from the campus wide central steam distribution system shall not be used in conjunction with a direct steam injection type humidifier. All steam from this system shall be condensed and the condensate returned to Abbott Power Plant through the central condensate return system. T. Animal Facilities. U. Wet Laboratories: General Guidelines for specific HVAC system requirements related to wet laboratories. V. Finalizing.
  9. 9. 9 HVAC industry and standards International ISO 16813:2006 is one of the ISO building environment standards.It establishes the general principles of building environment design. It takes into account the need to provide a healthy indoor environment for the occupants as well as the need to protect the environment for future generations and promote collaboration among the various parties involved in building environmental design for sustainability. ISO16813 is applicable to new construction and the retrofit of existing buildings. The building environmental design standard aims to:  provide the constraints concerning sustainability issues from the initial stage of the design process, with building and plant life cycle to be considered together with owning and operating costs from the beginning of the design process;  assess the proposed design with rational criteria for indoor air quality, thermal comfort, acoustical comfort, visual comfort, energy efficiency and HVAC system controls at every stage of the design process;  it erate decisions and evaluations of the design throughout the design process. North America United States In the United States, HVAC engineers generally are members of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, EPA Universal CFC certified, or locally engineer certified such as a Special to Chief Boilers License issued by the state or, in some jurisdictions, the city. ASHRAE is an international technical society for all individuals and organizations interested in HVAC. The Society, organized into regions, chapters, and student branches, allows exchange of HVAC knowledge and experiences for the benefit of the field's practitioners and the public. ASHRAE provides many opportunities to participate in the development of new knowledge via, for example, research and its many technical committees. These committees typically meet twice per year at the ASHRAE Annual and Winter Meetings. A popular product show, the AHR Expo, is held in conjunction with each winter meeting. The Society has approximately 50,000 members and has headquarters in Atlanta, Georgia. The most recognized standards for HVAC design are based on ASHRAE data. The most general of four volumes of the ASHRAE Handbook is Fundamentals; it includes heating and cooling calculations. Each volume of the ASHRAE Handbook is updated every four years. The design professional must consult ASHRAE data for the
  10. 10. 10 standards of design and care as the typical building codes provide little to no information on HVAC design practices; codes such as the UMC and IMC do include much detail on installation requirements, however. Other useful reference materials include items from SMACNA, ACGIH, and technical trade journals. American design standards are legislated in the Uniform Mechanical Code or International Mechanical Code. In certain states, counties, or cities, either of these codes may be adopted and amended via various legislative processes. These codes are updated and published by the International Association of Plumbing and Mechanical Officials (IAPMO) or the International Code Council (ICC) respectively, on a 3-year code development cycle. Typically, local building permit departments are charged with enforcement of these standards on private and certain public properties. In the United States and Canada, as well as throughout the world, HVAC contractors and Air Duct Cleaning companies are members ofNADCA, the National Air Duct Cleaners Association. NADCA was formed in 1989 as a non-profit association of companies engaged in the cleaning of HVAC air duct systems. Its mission was to promote source removal as the only acceptable method of cleaning and to establish industry standards for the association. NADCA has expanded its mission to include the representation of qualified member companies engaged in the assessment, cleaning, and restoration of HVAC systems, and to assist its members in providing high quality service to their customers. The goal of the association is to be the number one source for the HVAC air duct cleaning and restoration services. NADCA has experienced large membership growth in the United States, Canada and overseas and has been extremely successful with the training and certification of Air Systems Cleaning Specialists (ASCS)and Certified Ventilation Inspectors (CVI). The association has also published important standards and guidelines, educational materials, and other useful information for the consumers and members of NADCA. Standards include the Assessment, Cleaning and Restoration (ACR), Certified Ventilation Inspector (CVI) and other important guidelines. HVAC professionals in the US can receive training through formal training institutions, where most earn associate's degrees. Training for HVAC technicians includes classroom lectures and hands-on tasks, and can be followed by an apprenticeship wherein the recent graduate works alongside a professional HVAC technician for a temporary period.HVAC techs who have been trained can also be certified in areas such as air conditioning, heat pumps, gas heating, and commercial refrigeration.
  11. 11. 11 Europe United Kingdom The Chartered Institution of Building Services Engineers is a body that covers the essential Service (systems architecture) that allow buildings to operate. It includes the electro-technical, heating, ventilating, air conditioning, refrigeration and plumbing industries. To train as a building services engineer, the academic requirements are GCSEs (A-C) / Standard Grades (1-3) in Maths and Science, which are important in measurements, planning and theory. Employers will often want a degree in a branch of engineering, such as building environment engineering, electrical engineering or mechanical engineering. To become a full member of CIBSE, and so also to be registered by the Engineering Council UK as a chartered engineer, engineers must also attain an Honours Degree and a Masters Degree in a relevant engineering subject. CIBSE publishes several guides to HVAC design relevant to the UK market, and also the Republic of Ireland, Australia, New Zealand and Hong Kong. These guides include various recommended design criteria and standards, some of which are cited within the UK building regulations, and therefore form a legislative requirement for major building services works. The main guides are:  Guide A: Environmental Design  Guide B: Heating, Ventilating, Air Conditioning and Refrigeration  Guide C: Reference Data  Guide D: Transportation systems in Buildings  Guide E: Fire Safety Engineering  Guide F: Energy Efficiency in Buildings  Guide G: Public Health Engineering  Guide H: Building Control Systems  Guide J: Weather, Solar and Illuminance Data  Guide K: Electricity in Buildings  Guide L: Sustainability  Guide M: Maintenance Engineering and Management Within the construction sector, it is the job of the building services engineer to design and oversee the installation and maintenance of the essential services such as gas, electricity, water, heating and lighting, as well as many others. These all help to make buildings comfortable and healthy places to live and work in. Building Services is part of a sector that has over 51,000 businesses and employs represents 2%-3% of the GDP.
  12. 12. 12 Australia The Air Conditioning and Mechanical Contractors Association of Australia (AMCA), Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH), and CIBSE are responsible. Asia Asian architectural temperature-control have different priorities than European methods. For example, Asian heating traditionally focuses on maintaining temperatures of objects such as the floor or furnishings such as Kotatsu tables and directly warming people, as opposed to the Western focus, in modern periods, on designing air systems. Philippines The Philippine Society of Ventilating, Air Conditioning and Refrigerating Engineers (PSVARE) along with Philippine Society of Mechanical Engineers (PSME) govern on the codes and standards for HVAC / MVAC in the Philippines. India The Indian Society of Heating, Refrigerating and Air Conditioning Engineers (ISHRAE) was established to promote the HVAC industry in India. ISHRAE is an associate of ASHRAE. ISHRAE was started at Delhi in 1981 and a chapter was started in Bangalore in 1989. Between 1989 & 1993, ISHRAE chapters were formed in all major cities in India and also in the Middle East.