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- 1. Thermal control: Mechanical control Activedesign Prepared by Seid D.
- 2. Objectives of active(energy-based) thermal control ā¢ When cold discomfort prevails, to compensate for any net loss, by heating which uses some form of energy ā¢ When hot discomfort prevails, to remove any excess heat by cooling which uses some form of energy ā¢ When conditions vary diurnally between hot and cold discomfort, to compensate both excesses by a flexible heating-cooling system Prepared by Seid D.
- 3. Principle of heatingand air conditioning ā¢ To provide and maintain internal air conditions at a pre-determined state regardless of the time of the year, the season and the external atmospheric environment. To provide a precisely controlled indoor climate. Prepared by Seid D.
- 4. When is HVACreally necessary? If the health and comfort of the building occupant is already at RISK. Prepared by Seid D.
- 5. Problems with ActiveDesign ā¢ Technical ā Uneven distribution of heat or conditioned air ā Dryness or low humidity may result from heating ā Indirect condensation ā¢ Social ā The degree of sophistication in environmental controls depends on how much one is prepared to pay for it Prepared by Seid D.
- 6. Architectural Implications ā¢ Accommodationof any fuel storage: location of the plant room and shafts ā¢ The heat production plant and its flue ā¢ The routing and distribution of the distribution network: pipe for the water system, duct for the air system, choice and placement of emitters (grille or diffuser) In general HVAC is designed by a Mechanical Engineer/HVAC specialist so what will be the ARCHITECTās job ? Prepared by Seid D.
- 7. Zoning ā¢ Similar scheduleof use ā¢ Similar temperature requirements ā¢ Similar ventilation and air quality ā¢ Similar internal heat generation ā¢ Similar HVAC needs Prepared by Seid D.
- 8. Major parts ofHVAC 1. Source 1. Boiler and chiller ā to create cold and heat for the system to use 2. Cooling tower ā located outside to exhaust heat 2. Distribution 1. Air handlers ā to transfer heat and cold to air to be blown to the zones 2. System of ducts, control boxes and diffusers Prepared by Seid D.
- 9. Mechanical heating cycle Mechanicalcooling cycle Qc ā cooling load Qv ā outside ventilation Qw ā electric motor Work portions of the cycle is parasitical Prepared by Seid D.
- 10. General selection criteria Designconsiderations ā¢ Temperature ā¢ Relative humidity ā¢ Sound level and character ā¢ Quality of breathable air ā¢ Adjustment controls ā¢ Initial and operating cost ā¢ Ventilation rate ā¢ Occupant density and activity ā¢ Distribution system ā¢ Filter system Common building use ā¢ Residential facility ā¢ Commercial offices ā¢ Hotels and motels ā¢ Educational facilities ā¢ Hospitals ā¢ Manufacturing facilities Prepared by Seid D.
- 11. Types of heating/coolingsystems Systems for small buildings 1. Roof mounted package system 2. Forced-air central heating 3. Forced hot water heating 4. Evaporative cooling 5. Through-wall units and package terminal units 6. Electric baseboard convectors 7. Electric fan-forced unit heaters 8. Radiant heating 9. Wall furnace System for large buildings ā¢ Based on zoning Prepared by Seid D.
- 12. What type ofmechanical control is needed in a tropical climate? Undercooling is common Overheating is common Prepared by Seid D.
- 13. Recommended application Hot dryclimates ā¢ However high the afternoon maximum temperature, as long as the daily mean is not higher than the comfort limit, satisfactory control is possible without air conditioning, purely by structural means. Maritime desert climates ā¢ Air conditioning can be helpful ā¢ The building should be āsealedā or closeable ā¢ Should have small windows to reduce solar gain, good insulation and large thermal capacity to reduce peak loads Prepared by Seid D.
- 14. Warm-humid climates ā¢ Needsair conditioning because the air is both hot and humid, often remains warm overnight. ā¢ Without airconditioning ample air movement is necessary, hence the building should be as open and transparent for the wind as possible ā¢ If airconditioned the building should be closed and cooled below the outdoor temperature, thus the walls need to be insulated. Composite climates ā¢ Install airconditioning but to be operated only in warm- humid seasons ā¢ The discrepancy between outdoor and indoor conditions should not be excessive because it may acclimatize the occupants to low temperatures, thus making the outdoor overheated conditions even more intolerable. Prepared by Seid D.
- 15. Tropical upland climates ā¢If the building is well designed there is no need for airconditioning ā¢ Some external constraints e.g. urban site dictating the wrong building orientation, attached prestige value in e.g. a department store ā¢ Cool discomfort may occur where the heat deficit is small which warm clothing can solve. Local heating appliances may be used rarely. Prepared by Seid D.
- 16. PASSIVE VS. ACTIVEBUILDING DESIGN Prepared by Seid D.
- 17. Space heating concepts 1.Solar collection 1. Transparent or translucent materials 2. Southerly oriented 2. Thermal storage materials 1. Masonry units, sand, liquids 2. Adequate storage capacity 3. Heat distribution 3. Heat distribution 4. Control mechanisms 1. Vents 2. Dampers 3. Movable insulation 4. Shading devices Space cooling concepts 1. Site cooling 1. Vegetative control 2. Water bodies 3. Adjacent landform 4. Materials 2. Earth cooling 1. Groundwater 2. Earthās mass 3. Radiative cooling 1. Heat loss through the sky or cooler objects 4. Ventilative cooling 1. Cross ventilation 2. Double roofs, attics or walls 3. Induced or forced ventilation 5. Vapor cooling 1. Evaporative cooling 2. Dehumidification 6. Flywheel cooling 1. Internal thermal mass or rockbeds Elements of passive building design Prepared by Seid D.
- 18. Elements of active buildingdesign Its all about the indoor mechanical systemsā¦. Space heating equipment 1. āHeat raising plantā ā boiler or furnace 2. Distribution network ā ducting or piping 3. Heat emitter units ā diffusers, radiators or convectors Space cooling equipment 1. Propeller/ āmoverā 2. Filter 3. Washer 4. Humidifier 5. Cooler 6. Dehumidifier 7. Heater or reheater Prepared by Seid D.
- 19. 1. Direct systemsā heat is collected directly within space, for cooling, lost or dissipated directly from the space Passive design Heating strategy Cooling strategy Underheated period Overheated period Active design Heating strategy Cooling strategy Through-wall units and packaged terminal units Electric baseboard convectors Wall furnace Prepared by Seid D.
- 20. 2. Indirect systems ā heatgain or loss occurs at the weatherskin Heating strategy Cooling strategy Underheated period Overheated period Mass wall Water wall Roof pond Forced hot water heating Active design Heating strategy Cooling strategy Prepared by Seid D.
- 21. Heating strategy Coolingstrategy Underheated period Overheated period 3. Isolated systems ā heat gain or loss occurs away from the weatherskin Thermosiphon Sunspace Active design Heating strategy Cooling strategy Forced-air central heating Evaporative cooling Prepared by Seid D.
- 22. PASSIVE SOLAR HOUSE Preparedby Seid D.
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- 25. Villa 396, Germany Solarpanels for mechanical heating and air conditioning Prepared by Seid D.
- 26. Therefore the decision FORor AGAINST HVAC will be based on: 1. Comfort 2. Climatic and physical parameters 3. Social and economic factors Prepared by Seid D.