MODULE 3

• Topical design


  Design focused on a specific topic or theme
• Microclimate


  The climate of a small, specific area that may differ from the climate of the surrounding area
• Maaliwalas


  A Filipino concept related to comfort and well-being
• The aim of design with climate is to maintain comfort within buildings
• An analysis is usually carried out to ascertain how external conditions compare with the required conditions for comfort
• Optimum thermal conditions


  The best comfort conditions, where 50-75% of people feel comfortable
• Thermal balance of the human body

  • Body loses heat through convection, conduction, radiation, and evaporation
  • Thermal balance is achieved when heat loss equals heat gain

  
• Internal control of thermal balance

  • Shivering
  • Breathing
  • Sweating
• Factors affecting thermal comfort

  • Air temperature
  • Mean radiant temperature
  • Air velocity
  • Relative humidity
  • Intrinsic clothing
  • Level of activity
• Air temperature


  The dry bulb temperature, an important factor for comfort (16-28°C)

  
• Mean radiant temperature


  Radiation to and from enclosed surfaces, measured with a globe thermometer (16-28°C, difference from air temp not less than 5°C)

  
• Air velocity


  Helps with heat loss and evaporation, comfortable range is 0.1-1.0 m/s indoors, up to 2.0 m/s outdoors

  
• Relative humidity


  Comfort range is 20-90%, high humidity reduces effectiveness of sweating for cooling

  
• Intrinsic clothing


  Measured in clo units, comfort range is 0.5-1.0 clo
• Activity level


  Measured in metabolic rate (met), comfort range is 0.7-2.5 met
• Thermal index


  A scale that combines the effects of all thermal comfort factors
• Standard Effective Temperature (SET)


  A rational, physiologically-based index of comfort, expressed in terms of a uniform environment at 50% RH, 0.125 m/s air velocity, 1 met activity, and 0.6 clo clothing
• Effective Temperature (ET)


  The temperature of a still, saturated atmosphere that would produce the same effect as the actual atmosphere, considering RH, air velocity, and air temperature

  
• Corrected Effective Temperature


  An improvement on ET, considering radiation effects as a fourth determinant of comfort

  
• Using the Effective Temperature nomogram

  To determine the Effective Temperature given dry/globe temp, wet bulb temp, and air velocity

  
• After determining the Effective Temperature, it must be compared to comfort limits

  
• Effective Temperature Index (ET)


  The most widely used thermal index

  
• Using the Effective Temperature nomogram

  1. Mark globe or air temperature on left scale

  2. Mark wet bulb temperature on right scale

  3. Join the two points

  4. Determine point of intersection with air velocity line

  5. Read the Effective Temperature

  
• Effective Temperature


  • Compared to comfort limits
  • Lower limit: 22°C
  • Optimum: 25°C
  • Upper limit: 27°C

  
• Corrected Effective Temperature


  Uses globe temperature instead of air temperature

  
• Resultant Temperature (RT)


  Improvement on ET, but unreliable for tropical conditions as it does not sufficiently incorporate cooling effects of air movement over 35°C and 80% RH

  
• Heat Stress Index (HSI)

  Reliable between 27-35°C, 30-80% RH, takes metabolic heat production as indication of heat stress

  
• Equivalent Warmth (EW)


  Based on reactions of 2000 factory workers, takes into account air temperature, RH and mean radiant temperature, reliable up to 35°C with low RH and 30°C with high RH, underestimates cooling effect of air movement at high humidity
• Equatorial Comfort Index (ECI)

  Similar to ET, accommodates effects of temperature, humidity and air movement

  
• Predicted Four Hour Sweat Rate (P4SR)


  Considers heat stresses experienced by seamen, indicated by sweat rate, pulse and internal temperature, unsuitable for temperatures below 28°C, underestimates cooling effects of air movement at high humidities
• Operative Temperature (OT)


  Combines effects of radiation and air temperature, similar to EW

  
• Index of Thermal Stress (ITS)

  Calculated cooling rate produced by sweating to maintain thermal balance, reliable between comfort and severe stress if thermal equilibrium can be maintained
• Bioclimatic Chart


  Defines comfort zone in terms of dry bulb temperature and RH, indicates effects of air movement and radiation

  
• Using the Bioclimatic Chart

  1. Plot monthly min temp and max RH, and monthly max temp and min RH

  2. Join the two points

  3. Use wind velocity and solar radiation to determine thermal stress

  
• Mahoney Scale


  Determines hot or cold discomfort for each month based on temperature and RH, with different limits for day and night, and hot, average and cold climates

  
• Evans Scale


  Similar to Mahoney Scale, also recognizes conditions where mechanical aids are needed for comfort
• Choice of thermal index depends on purpose of analysis, data availability, simplicity, and range of application

  
• For student projects, common indices used are Bioclimatic Chart, Effective Temperature, Standard Effective Temperature, Mahoney Scale, or Evans Scale
• Comfort limits may vary slightly from those proposed by indices, depending on local climate

  
• For extensive analyses, computer programs like COLDHOT are advisable