ALMOND THREE EFFECT THERMAL COMFORT BUILDING CLIMATOLOGY ARC

ALMOND THREE EFFECT THERMAL COMFORT BUILDING CLIMATOLOGY ARC 810 DEPARTMENT OF ARCHITECTURE Federal university of technology Akure Nigeria ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

OUTLINE q. INTRODUCTION q. BASIC CONCEPTS OF THERMAL COMFORT q. THERMAL BALANCE OF THE HUMAN BODY q. FACTORS AFFECTING THERMAL COMFORT q. THERMAL INDICES q. APPLICABILITY OF THE INDICES ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

INTRODUCTION q The human body maintains a thermal balance by controlling heat loss and gain q. The six major factors that affect comfort are ü air temperature ümean radiant temperature üair velocity üthe relative humidity üintrinsic Clothing and ülevel of activity ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

BASIC CONCEPTS OF THERMAL COMFORT q Design of buildings with climate aims at maintaining comfort within and outside the building q An analysis is usually carried out to ascertain the comfort limit q. Comfort is subjective in nature q The best comfort conditions are called optimum thermal conditions q Under such conditions only 50 -75% people feels comfortable ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal balance of the human body Energy is got by the body through metabolism There are two types of metabolism • Basal metabolism • Muscular metabolism Body gains heat through • Conduction • Convection • radiation ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal balance of the human body Body loses heat through • Convection • Conduction • Radiation • Evaporation ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal balance of the human body q. Body loses heat through üConvection üConduction üRadiation üevaporation Thermal balance is achieved Heat loss heat gain ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal balance of the human body chart showing an equilibrium of heat loss and heat gain ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal balance of the human body Control is maintained internally through • Shivering • Breathing • Sweating ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal balance of the human body ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal balance of the human body Control is maintained externally through clothing activity rate posture choice of location ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Factors Affecting Thermal Comfort air tempera ture mean radiant tempera ture air velocity relative humidity intrinsic clothing level of activity ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Factors Affecting Thermal Comfort Others factors that may have an effect on the sensation of comfort are age, sex, acclimatisation, body shape, health ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Factors Affecting Thermal Comfort AIR TEMPERATURE It is the dry bulb temperature Its an important factor Low temperature makes people feel cold High temperature makes people feel hot Comfort can be achieved (between 16 -28 degree Celsius) ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Factors Affecting Thermal Comfort MEAN RADIANT TEMPERATUR E • Its radiation to and from an enclosed surface • Measured with globe thermometer • Calculated from globe temperature using • Air temperature • Velocity ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

MEAN RADIANT TEMPERATURE CONTINUED Comfort is achieved if • Globe temperature is between (16 -28 degree Celsius) • Difference between dry and mean radiant temperature is not less than 5 degree Celsius ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Factors Affecting Thermal Comfort of up to 0. 1 metre per second may lead to a feeling of stuffiness indoors Helps on the body by • Increasing heat loss during sweating • Enhancing evaporation of sweat; causing cooling of 0. 1 to 1. 0 m/s are comfortable indoors above this level there is discomfort AIR VELOCITY ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Air velocity continued A kata thermometer is used to measure air due to low velocities. Outdoors, wind speeds of up to 2. 0 m/s can help achieve comfort, especially when the humidity is high. Wind speeds of over 5. 0 m/s lead to considerable discomfort ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Air velocity continued Outdoors, wind speeds of up to 2. 0 m/s can help achieve comfort, • when the humidity is high Wind speeds of over 5. 0 m/s lead to considerable discomfort. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Factors Affecting Thermal Comfort The Relative Humidity When humidity is low • The air is dry • Sweating is more effective for body cooling When humidity is high • The air is damp and clammy • Sweating no longer cools the body effectively ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Relative Humidity continued Thermal comfort as achieved between 20 -90 % ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Factors Affecting Thermal Comfort The Intrinsic Clothing • Clothing is measured in clo units: • 0. 5 clo => a pair of shorts for men and a cotton dress for women ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Intrinsic clothing continued The Intrinsic Clothing • 1. 0 clo => normal business suit, shirt and underwear • 2. 0 clo => outdoor winter clothing • The range of intrinsic clothing for thermal comfort is between 0. 5 to 1. 0 clo. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

PICTURE SHOWING EFFECT OF THERMAL FACTORS ON THE BODY ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Factors Affecting Thermal Comfort The Activity • represents the metabolic rate • The higher the activity • the more heat is produced by the body • metabolic rate is measured in W/m • rate for a person sitting is about 58 W/m • this is the basic unit of activity known as "met“ ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The activity continued The Activity As such Sitting 1 met Sleeping 0. 7 met Standing relaxed 1. 2 met Dancing 2. 4 -4. 4 met Comfort can be maintain ed with metaboli c rates Heavy from machin about 0. 7 e work to 2. 5 3. 5 met. 4. 5 met ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

THERMAL INDICES Need for a Thermal Index a need for a scale that will combine the effects of all factors discussed above Such a scale is called a thermal index or a comfort scale. Arbuthnot established the first milestone in 1733 • pointed out the chilling effects of wind by dispersing the layer of warm, moist air around the body ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Need for thermal index continued The more salient points include Was quickly followed by several developments as detailed by Markus and Morris(1980) proposal of the Effective Temperature Index (ET) (Houghton and Yaglou 1923) Corrected Effective Temperature Index (CET) proposed(Bedford 1946) ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Need for thermal index continued The Equivalent Temperature (1929) Other important concepts include The Operative Temperature The Standard Effective Temperature. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Examples of Thermal indices Its a rational physiologicallybased index of comfort The Standard Effective Temperature (SET) expresses any environment, clothing and activity level in terms of A uniform environment standardised at • 50 percent RH • air velocity of 0. 125 m/s • activity of 1 met • intrinsic clothing at 0. 6 clo ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Standard effective temperature continued Note that • 0. 125 m/s is the velocity of still air in a room • 1 met is equivalent to sedentary metabolic rate at 58 W/m • zero external work • 0. 6 clo is equivalent to normal, lightweight, indoor clothing. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Standard effective temperature continued To determine SET the following variables should be known • the relative humidity • the air temperature • the mean radiant • temperature • the air velocity • the intrinsic clothing • the activity ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Standard effective temperature continued The kata thermometer ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Effective Temperature (ET) Definition Its the temperature of a still, saturated atmosphere, which would, in the absence of radiation, produce the same effect as the atmosphere in question was developed in 1923 by Houghton and Yaglou while working for ASHRAE ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The effective temperature continued It combines the effects of the following: the relative humidity the air velocity the air temperature ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal comfort chart for the Effective Temperature index. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Corrected Effective Temperature q it is an improvement on the ET scale as it considers radiation effects as a fourth determinant of comfort ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Use Of The Effective Temperature Nomogram can be used to determine the Effective Temperature given: widely used thermal index is the Effective Temperature Index (ET) • the dry bulb or globe temperature • the wet bulb temperature • the air velocity ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Use Of The Effective Temperature Nomogram To find the Effective Temperature for a given set of conditions: • the globe or air temperature is marked on the scale on the left hand side of the nomogram. • the wet bulb temperature is marked on the scale on the right hand side of the nomogram. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Use Of The Effective Temperature Nomogram These two points are joined by a line. The point of intersection of this line and the line representing the appropriate air velocity is determined. The Effective Temperature is then read. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Use Of The Effective Temperature Nomogram Effective Temperature nomogram for persons wearing normal clothes. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Effective Temperature nomogram for persons stripped to the waist. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Use Of The Effective Temperature Nomogram the determined effective temperature value is compared to the comfort limits Values for tropical comfort limits are • Lower limits = 22 degree Celsius • optimum temperature = 25 degree Celsius • Upper limit = 27 degree Celsius ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Use Of The Effective Temperature Nomogram recent research by Ogunsote (1988) indicates that comfort limits valid for Nigeria are 20 -25 degrees Celsius same nomogram is used for both Effective and corrected effective Temperatures. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

THERMAL INDICES The Resultant Temperature (RT) its an improvement on the ET the nomograms defining them are almost identical Was developed in France by Missenard • is considered unreliable tropical conditions ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Resultant Temperature (RT) continued it does not sufficiently incorporate the cooling effect of air movement over • 35 degrees Celsius • 80 percent RH ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Resultant Temperature (RT) continued Chart of the Resultant Temperature index. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

THERMAL INDICES The Heat Stress Index (HSI) • Its reliable between • 27 and 35 degrees Celsius • 30 and 80 percent RH • heat production of subjects doing various kinds of work taken as an indication of heat stress ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

THERMAL INDICES The Equivalent Warmth (EW) • was developed by Bedford in England • Is based on the reaction of 2000 factory workers • engaged in light work • under varying indoor conditions • takes into account • Temperature • RH • mean radiant temperature ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Equivalent Warmth continued Its reliable within the comfort zone up to • 35 degrees Celsius with low RH • 30 degrees Celsius with high RH it under-estimates the cooling effect of air movement at high humidities ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

THERMAL INDICES The Equatorial Comfort Index (ECI) its similar to the ET was developed by Webb in Singapore Temperature It accommodates the effects of Humidity Air movement ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

THERMAL INDICES The • Developed by British naval authority Predicted • Considering the special heat stresses Four Hour experienced by seamen • is indicated by their Sweat • pulse • internal temperature Rate • rate of sweat secretion from the body (P 4 SR) ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Predicted Four Hour Sweat Rate continued Its considered unsuitable for temperatures below 28 degrees Celsius it underestimates the cooling effects of air movement at high humidities ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Predicted Four Hour Sweat Rate continued Factors considered are • Air temperature • Humidity • air movement • metabolic rate • clothing • Mean radiant temperature of the surrounding ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal indices The Operative Temperatur e (OT) • Definition • Its uniform temperature of an imaginary enclosure in which man will exchange the same dry heat by radiation and convection as in the actual environment • It combines the effects of radiation and air temperature • It was developed by Winslow, Herrington and Gagge • Its similar to the EW ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Operative Temperature continued Operative Temperature chart. Air velocity = 0. 1 m/s and activity = 1 met. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal indices The Index Of Thermal Stress (ITS) • definition • its the calculated cooling rate produced by sweating would maintain thermal balance under the given conditions as established from first principles by Givoni (1976) • It is reliable in the range of conditions between comfort and severe stress provided • that thermal equilibrium can be maintained ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal indices The Bioclimatic Chart Victor Olgyay's conviction that there is no point in defining a single-figure index, as each of the components are controllable by different means resulted in the construction of the bioclimatic chart ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Bioclimatic chart continued The comfort zone is defined in terms of the dry bulb temperature the RH the effects of air movements and radiation on the comfort zone are indicated ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Bioclimatic chart continued Use of the Bioclimatic Chart • The bioclimatic chart is popular mainly because Of • its simplicity of use • the ease with which results can be interpreted for design purposes ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued For very simple analysis • the average monthly air temperatures may be used • relative humidities may be used The use of the minima and maxima of these climatic variables is however more informative and this is the procedure described here. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued The bioclimatic chart ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued The monthly minima and maxima of air temperature and relative humidity are usually readily available data and are sufficient for this analysis of it is advisable to obtain the average monthly wind velocity Mean monthly solar radiation ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued A reduction factor should be used to convert the wind velocity to air movement at the level of the human body (see table 1) These two Take the variables monthly mean minimum define a point temperature on the and the Bioclimatic monthly mean Chart maximum ARC 810: Building Climatology relative Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued Condition Mean daily humidity Diurnal range High temperature over 27 and high humidity by over 27. 5 day over 70% - 50 - 70% ? 10 C High temperature and high diurnal range over 32. 5 0 - 30% - over 30. 5 30 - 50% - over 29. 5 50 - 70% >10 C over 38 0 - 30% - over 37 30 - 50% - over 35. 5 50 – 70% >10 C over 32 over 70% ? 10 C Excessive discomfort Mean daily temp. ( C) ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued Day and night comfort but with high diurnal range 10 - 32. 5 0 - 30% >10 C 10 - 30. 5 30 - 50% >10 C 10 - 29. 5 50 - 70% >10 C 10 - 29 over 70% >10 C Low day temperatures 15 - 18 (fresh) - - 10 - 15 (cool) - - all conditions not included above 70% - 50 - 70% ? 10 C Day comfort High temperature above 25. 5 and high humidity by night above 26 ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued High temperature and low humidity by night above 27. 5 0 - 30% - above 26. 5 30 - 50% - above 26 50 - 70% >10 C Low night temperatures below 10 - - Table 1: Temperature and humidity limits for different forms of discomfort ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued Take the monthly mean • maximum temperature and the • minimum relative humidity use this to define a second point for the same month of January Join these two points together with a straight line ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued Use the wind velocity and the solar radiation for the same month to determine whether • there is hot discomfort • cold discomfort • comfort for the two points You may indicate thermal stress thus ascertained symbolically ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued Repeat the process for the remaining eleven months of the Year This chart gives an indication of the duration and nature of thermal stress throughout the year and design decisions can be made on this basis ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Use of Bioclimatic chart continued Example of the use of the bioclimatic chart for Zaria. ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Thermal indices The Mahoney Scale • Carl Mahoney proposed a scale which is capable of determining • hot discomfort for each month of the year • cold discomfort for each month of the year • capable of doing this on the basis of only • relative humidity data • temperature data ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Mahoney Scale continued It differentiates between day and night comfort limits • lower limits for the night There are different limits for hot, average and cold climates, and these are presented in table 2 ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Mahoney Scale continued Comfort limits proposed by Mahoney ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

thermal indices The Evans Scale The limits are for • The comfort limits for climatic design proposed by Martin Evans are very similar to the ones proposed by Carl Mahoney • hot comfortable • cold climates as shown in table 3 ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Evans Scale continued Table 3: Comfort temperature ranges according to Evans ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

The Evans Scale continued Also recognizes that there are various combinations of climatic variables which produce conditions under which natural means are not sufficient for the attainment of comfort and mechanical aids are needed These conditions are shown in table 1 ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Applicability of the Indices The choice of a thermal index for climatic analysis is closely related to the • purpose of the analysis • the availability of data • the simplicity of the particular thermal index Also of importance is the range of application of the particular index Nomograms where necessary should of course be available ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Applicability of the Indices continued For student projects the following should be commonly used • The Bioclimatic Chart • The Effective Temperature • The Standard Effective Temperature • The Mahoney Scale • The Evans Scale are ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria

Applicability of the Indices continued It should be noted that there may be slight variations in the comfort limits proposed by these indices and those actually applicable in the Nigerian climate For extensive analyses the use of a computer program such as COLDHOT is advisable ARC 810: Building Climatology Department of Architecture, Federal University of Technology, Akure, Nigeria