125 tie thermal comfort ii - cvut.cz

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ČVUT v Praze

Fakulta stavební

Katedra technických zařízení budov

125 TIE

Theory of Indoor Environment

Thermal comfort

prof. Ing. Karel Kabele, CSc.

A227b

[email protected]

PROBLEMS RELATED TO

INDOOR ENVIRONMENTAL

QUALITYTIE 2122ZS prof. Karel Kabele, CVUT 103

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Indoor Environment and Health

• Sick Building Syndrome (SBS)

– set of symptoms and problems associated with

users stay in a building without a clear cause

Symptoms

– Complaints of discomfort, irritation of eyes, nose,

headaches, fatigue, difficulty in concentrating;

– The cause is not known;

– Most problems disappear after leaving the

building.

TIE 2122ZS prof. Karel Kabele, CVUT 104

Indoor Environment and Health

Building Related Illness (BRI)

– Diagnosed disease associated with stay in a

building with a clear cause: occurrence of mold,

gases concentration, …

Symptoms

– Users complain about the cold, stiff neck, fever,

convulsions

– There are known causes - such as drafts, poor job

– Remedy usually lasts longer and the problems do

not stop after leaving the building


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Adaptation

There may be defined three categories of adaptation toindoor climate (Folk 1974, 1981, Goldsmith 1974, Prosser1958, Clark and Edholm 1985):

1. Behavioural Adjustment;

2. Physiological;

3. Psychological.

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The three components of adaptation to indoor climate

(adapted from ASHRAE RP 884)

Adaptation to Indoor Climate

AdjustmentBehavioural /technological changes to the heat balance

(clothing and activity,personal environmental

control)

AcclimatizationLong term physiological

adaptation to climate (genetic adaptation)

HabituationPsychological adaptation –

changing expectations (expectations and thermal

memory, adaptive opportunity)

prof. Karel Kabele, CVUT 109

Negative Effect of IE on Health

• Direct noticable comfort-related complaints by the

senses – smell, noise, heat, cold, draught,…

• Systemic effects – tiredness, poor concentration,

depression

• Irritation, allergic and hyper–reactive effects –

irritation of mucous membranes of the skin and

respiratory tract, asthma, rashes on the skin, sun

burn, hearing loss, damage of eyes,…

• Infectious diseases – Legionnaires´disease

• Toxic chronic effects that slowly increase or appear

(cancer)

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Bluyssen 2009


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Factors of indoor climate with known

quantitative effects on productivity

• Ventilation and sick leave

• Ventilation and work performance

• Perceived indoor air quality and task

performance

• Temperature and work performance

TIE 2122ZSRehva GB 6


Rehva GB 6

Ventilation rates and sick leave


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Temperature and performance

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Rehva GB 6


THERMAL COMFORTTIE 2122ZS

Indoorenvironmentof buildings

Thermalcomfort

Air

Lighting

Acoustics

Psychic

Elmgfield


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THEORETICAL BACKGROUND


Fundamentals overview

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• Heat

– Heat is the form of energy transferred between a system and its

surroundings due solely to a temperature difference between

the system and some parts of its surroundings.

• Temperature

– State variable describing kinetics energy of the particles of the

system

• Thermodynamic /Kelvin/ T [K]

• Celsius t [°C] t= T-273,15

• Fahrenheit [°F] 1°F=5/9°C (°F-32).5/9=°C


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Basic laws of thermodynamics

Zeroth law

– There is a state variable TEMPERATURE. Two

systems at the same temperature are in

thermodynamics equilibrium.

– If two thermodynamic systems are in thermal

equilibrium with a third, they are also in thermal

equilibrium with each other



First law• The increase in the internal energy of a

thermodynamic system is equal to the

amount of heat energy added to the system

minus the work done by the system on the

surroundings.

The energy of the world is constant. Clausius [1865]

WQU −=

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The change in internal energy of a system is equal to the heat added

to the system minus the work done by the system


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Second law

• The second law is concerned with entropy (S), which

is a measure of disorder. The entropy of the universe

increases.->

• Heat cannot of itself pass from a colder to a hotter

body. Haynie[2001]



Third law

• As a system approaches absolute zero

of temperature, all processes cease and

the entropy of the system approaches a

minimum value

• It is impossible to cool a body to

absolute zero by any finite process.

Nernst [1912]


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Heat transfer modes

• Heat Conduction

– Heat is transferred between two

systems through a connecting

medium, Fourier law x

TkA

t

Q

−=

−=

SdSTk

t

Q

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Q is the amount of heat transferred [J/s]

t is the time taken [s]

k is the material's conductivity [W/m.K]

S,A is the surface through which the heat is flowing

[m2] ,

T is the temperature [K].

B


Heat transfer

Heat Convection

– Macroscopic movement of

the matter in the forms of

convection currents.

– Natural convection

– Forced convection

– Fourier-Kirchhof equation

– Grashof, Pecklet number

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2 2 2

2 2 2.x y z

T T T T T T Tv v v a

t x y z x y z

+ + + = + +


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http://en.wikipedia.org/wiki/Thermal_conductivity

http://en.wikipedia.org/wiki/Image:Linear_Heat_flow.svg

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Heat transfer

Radiation

– Electromagnetic waves

– Stefan-Boltzmann law

( )4 4

1,2 1,2 1 2Q S T T = −

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4

00

bE I d T

= =

85,67.10 −=

max

0,0028978213

T =

Stefan-Boltzman constant

[W/(m2K4)]

Wien's law

[m]

1

T1

2

E1

Q1,2= E1- E2

E2

T2 >

ε1 ε2


Psychrometry

• Psychrometrics orpsychrometry are terms usedto describe the field of engineering concerned withthe determination of physicaland thermodynamicproperties of gas-vapormixtures

• Dry-bulb, wet-bulb

• AHU processes – air drying, cooling, mixing, humidifacition

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Fan

Wet bulb

temperatureDry bulb

temperature

Wet

„sock“

Air


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Mollier diagram

Dew Point

Enthalpy

TEMPERATURE

Specific Humidityg/kg

Dry-Bulb

Temperature

Wet-Bulb

Temperature

Relative Humidity


Sensible x Latent Heat

Entalpy of dry air = sensible heat

ha = cpa . t

Entalpy of water vapor = latent heat

hw = cpw . t + hwe

Enthalpy of moist air

h = ha + x hw

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where

h = Entalpy of moist air (kJ/kg)

ha = Entalpy of dry air (kJ/kg)

x = specific humidity(kg/kg)

hw = Entalpy of water vapor (kJ/kg)

t = air temperature = water vapor temperature (oC)

cpa = specific heat of dry air (kJ/kg.oC, kWs/kg.K) =1.006 (kJ/kgoC)

cpw = specific heat of water vapor (kJ/kg.oC, kWs/kg.K) =1.84 (kJ/kg.oC)

hwe = latent heat of vaporization of water at 0 ° C (kJ/kg) = 2,502 (kJ/kg)

Radiation Convection Evaporation, condensation


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THERMAL COMFORTTIE 2122ZS

Indoorenvironmentof buildings

Thermalcomfort

Air

Lighting

Acoustics

Psychic

Elmgfield


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Thermal comfort

State of the mind expressing

satisfaction with the

environment related to heat

and moisture flows between

the human body and its

surroundings…

… feeling neutrally.


https://www.hpac.com/

https://www.electronichouse.com

https://appliedenergysaving.com.au

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Thermal comfort

prof. Karel Kabele, CVUT

• Human heat production –metabolic heat M

• Heat transfer between the

body and the -

environment Q

– Respiration

– Convection

– Radiation

– Conduction

– Evaporation

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Thermal comfort




body and the -

environment Q

– Respiration

– Convection

– Radiation

– Conduction

– Evaporation

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Thermal comfort




body and the -

environment Q

– Respiration

– Convection

– Radiation

– Conduction

– Evaporation

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Thermal comfort




body and the -

environment Q

– Respiration

– Convection

– Radiation

– Conduction

– Evaporation

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Člověk z hlediska tepelné energie




body and the -

environment Q

– Respiration

– Convection

– Radiation

– Conduction

– Evaporation

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Thermal comfort




body and the -

environment Q

– Respiration

– Convection

– Radiation

– Conduction

– Evaporation

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Thermal comfort


• Human heat production –

metabolic heat M


body and the -

environment Q

– Respiration

– Convection

– Radiation

– Conduction

– Evaporation

Heat balance equationM = Q thermal comfortM > Q warmM < Q cold

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Factors Influencing Thermal

Comfort

• Factors of Human

– Metabolic Heat

– Clothing Insulation

• Factors of Environment

– Air Temperature (Dry-Bulb)

– Relative Humidity

– Air Velocity

– Radiation (Mean Radiant Temperature)


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Factors of Human - Metabolic Heat

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BasalMetabolism

MuscleMetabolism

Metabolic

Heat



• Unit 1 MET – is defined as the

production of energy of sitting person,

when an adult consumes 3.4 ml

respectively 3.6 milliliters of oxygen

per kilogram of body weight per minute

• 1 Met = 58 W/m2

• 0 up to 16,9 Met


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Metabolic Heat

• basal metabolic rate - heat generated by biological

processes in the body necessary for life

BMR men = 66 + (13,7 x M) + (5,0 x H) – (6,8 x A)BMR women = 655 + (9,6 x M) + (1,85 x H) – (4,7 x A)

M – weight in kg; H – height in cm; A – age in years;

BMR – basal metabolism in kcal



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30

50

70

0 10 20 30 40 50 60

W/m

2

AGE

Basal Metabolismx age, sex

MUŽI

ŽENY

Source: Jokl 2002


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Activity Metabolic heat

W/m2 met

Lying 46 0,8

Relaxed Sitting 58 1,0

Work in a sitting position (offices, apartments,

schools, laboratories)

70 1,2

Standing, medium work (salesman, housework, work

on machines)

93 1,6

EN ISO 7730


Jokl 2007


Metabolic Heat

• directly proportional to the surface of the human

body

• Human body surface according to Du-Bois

𝑩𝑺𝑨 = ( 𝑯𝟎,𝟕𝟐𝟓×𝑾𝟎,𝟒𝟐𝟓)×0,007184

BSA Body Surface Area (cca 1,9) [m2]

W weight in kg,

H height in cm

• E.g.: 58 W/m2 x 1,8 m2 = 104 W


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20

0

50

100

150

200

250

300

350

W

Heat Loads from People

Latent heat

Radiation

Convection

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Kabele 2007


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Icl Daily common clothing

0,3 panties, T-shirt, light socks, sandals

0,45 briefs, panties, stockings, light dresses with sleeves, sandals

0,5 pants, shirts with short sleeves, light trousers, light socks, shoes

0,6 pants, shirts, light pants, socks, shoes

0,7 underwear, shirts, pants, socks, shoes (panties, petticoat, stockings,

dresses, shoes)

clo < 0,50,6 - 1,2 >3,5

Unit 1 clo=0,155m2.K/W

Factors of Human - ClothingEN ISO 7730


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Factors Influencing Thermal

Comfort

• Factors of Human

– Metabolic Heat

– Clothing Insulation

• Factors of Environment

– Air Temperature

– Relative Humidity

– Air Velocity

– Radiation (Mean Radiant Temperature)


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Factors of the Environment

Air temperatureState variable describing the kinetic energy of particles of the system.

Thermodynamic /Kelvin/ T [K]

Celsius t [°C] t= T-273,15

Fahrenheit [°F] 1°F=5/9°C (°F-32).5/9 = °C

The air temperature is without the influence of radiation, measured with a

thermometer, protected from radiation heat source.


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Mean Radiant Temperature MRT(also effective temperature of the surrounding surfaces, medium temperature of radiation) is defined as the uniform temperature of an imaginary enclosure in which the radiant heat transfer from the human body is equal to the radiant heat transfer in the actual non-uniform enclosure

• where

– tr = mean radiant temperature

– Ti = temperature of the surrounding surface i, i=1,2,....,n

– φrn = shape factor which indicates the fraction of total radiant energyleaving the clothing surface 0 and arriving directly on surface i, i=1,2,...n

273.T....Tt 4 4nrn

41r1r −++=



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Where top = operative temperatureta = air temperaturetr = mean radiant temperature (MRT)hc = convective heat transfer coefficient

hr = mean radiative heat transfer coefficient

rc

rraco

hh

ththt

+

+= Calculated value

Operative Temperatureis defined as a uniform temperature of a radiantly black enclosure in which an

occupant would exchange the same amount of heat by radiation plus convection

as in the actual nonuniform environment. It can be defined as the average of the

mean radiant and ambient air temperatures, weighted by their respective heat

transfer coefficients.



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go tt Naměření hodnota

Resultant Temperature(globe temperature) is measured with a globe thermometer, it includes the effect

of air velocity and radiant heat source.

Jokl 1984

Valid for low air velocity (up to 0,2 m/s)

and small differencies between ta and tr

(up to 4 °C),



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Measured value

Stereo temperaturemeasured directional globe thermometer, includes the effect of air velocity and

uniformity of radiant heat source

Jokl,Jirák2005



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Air Humidity

• Specific humidity 𝑊𝑎 =𝑀𝑣

𝑀𝑎[g/g]

– Wa specific humidity;

– Mv weight of water vapor;

– Ma mass of dry air in a given sample of humid air.

• Relative humidity RH = 100 ×𝑝𝑎

𝑝𝑎𝑠[%]

– pa partial pressure of water vapor;

– pas partial pressure of saturated water vapor at the same temperature and the same total pressure

• Dew point– Temperature at which the partial pressure of

water vapor in the air is equal to the partial pressure of saturated water vapor

• Psychrometer– Dry-Bulb tempearture

– Wet-Bulb temperature

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Fan

Wet-Bulb

Temperature

Dry-Bulb

Temperature

Wet

„stocking“

Air


• HIGH RELATIVE HUMIDITY

is unpleasantly felt as stuffy if also

associated with high air temperature.

However, it may cause:

occurrence of condensation on building

structures and occurrence of mold and

mites

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LOW RELATIVE HUMIDITYcauses not only feelings of dryness, but dryness of mucous membranes of nose and eyes (min. 30%, critical value 15%).


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Relative humidity

Mites

Mold

SurvivingOptimal

zone


Jokl 1984

SOURCES OF WATER VAPOR

Water vapor content in the

interior is given by water

vapor in the exterior andby interior sources and

activities of man.


https://www.labenvironex.comhttps://www.labenvironex.com/en/environment/

bacteria-and-mould-analyses/moisture-

sources-in-houses/

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Air flow

- Air velocity- Flow direction- Speed fluctuation

Mostly this is a turbulent flow, difficult to measure.omnidirectional probes x three-dimensional, long-term measurements

Human perception of air velocity:

0 m/s unpleasant, stuffy air0,1 - 0,3 m/s mostly pleasant but dependent on temperature and

clothingAbove 0,3 m/s according to temperature

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Measuring

equipment


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THERMAL COMFORT

ASSESSMENT


Thermal discomfort

Within thermal discomfort may be considered complaints about:

• high temperatures;

• low temperatures;

• varying temperatures;

• draughts;

• radiation;

• hot or cold feet (floors).

In the short term, the thermal climate may have health effects as a

consequence. Examples of health problems which may be related to this

are:

• Headache (for example associated to low temperatures and high

humidities (Bianchi et al, 2003));

• Fatigue;

• Dizziness;

• Motor system detriment (for low temperatures).

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STANDARDS

• (ČSN) EN ISO 7730 Ergonomics of the thermal environment -

Analytical determination and interpretation of thermal comfort

using calculation of the PMV and PPD indices and local thermal

comfort criteria (10.2006)

• ČSN EN 16798-1Energy performance of buildings – Ventilation for

buildings – Part 1: Indoor environmental input parameters for

design and assessment of energy performance of buildings

addressing indoor air quality, thermal environment, lighting and

acoustics – Module M1-6 (8/2020)

• ČSN EN ISO 10551 Ergonomics of the physical environment -

Subjective judgement scales for assessing physical environments

(3/2020)


ČSN EN ISO 7730 ERGONOMICS OF THE THERMAL

ENVIRONMENT - ANALYTICAL DETERMINATION

AND INTERPRETATION OF THERMAL COMFORT

USING CALCULATION OF THE PMV AND PPD

INDICES AND LOCAL THERMAL COMFORT CRITERIA


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Thermal comfort

TC assesment - indexes:

• PMV (Predicted Mean Vote)

– mean thermal feeling of a

person

• PPD (Predicted Percentage

of Dissatisfied)

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PPD

PMV – 7 grades

3, 2, 1, 0 ,-1,-2,-3

hot, warm, slightly warm

neutral

Slightly cool, cool, coldPMV

Prof. Fanger


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Calculation of PMV and PPD according to

EN ISO 7730

( ) ( )

( ) ( ) ( )

( ) ( ) ( )

3

0,036 5

4 48

3,05 10 5733 6,99 0,42

(0,303 0,028) 58,15 1,7 10 5867 0,0014 34

3,96 10 273 273

a

M

a a

cl cl r cl c cl a

M W M W p

PMV e M W M p M t

f t t f h t t

−

− −

−

− − − − − −

= + − − − − − − − + − + − −

4 2(0.03353 0.2179 )100 95 PMV PMVPPD e− + = −

PMV predicted mean vote

PPD predicted persentage of

dissatisfied

M energy output W/m2

W external mechanical power W/m2

(mostly equal to zero)

fcl surface portion of clothed body to

naked body

tcl surface temperature of

clothing °C

ta air temperature°C

tr mean radiant temperature°C

pa partial pressure of water

vapor Pa

hc convective heat transfer

coefficient W/m2K


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Thermal comfort

• EN ISO 7730 – parameters especially for HVAC systems

design

• Main parameters of IEQ in Appendix A of EN 16798-1 3

categories of thermal comfort according to PPD and PMV

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PMV - predicted mean vote, PPD - predicted percentage of dissatisfied

Category of indoor thermal environment

Thermal state of the body as a whole

PPD PMV

A 6% − 0,2 < PMV < + 0,2

B 10% − 0,5 < PMV < + 0,5

C 15% − 0,7 < PMV < + 0,7

Categories of thermal environment (EN ISO 7730)


Optimal resultant temperature

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Category A (PPD<6%)

CLOTHING

AC

TIV

ITY


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Indoor resultant (operative) temperature

Type of building,Space

Clothing, winter (clo)

Activity(met)

Category of indoor environment

Operative temperature, winter (°C)

Office 1,0 1,2

A 21,0 - 23,0

B 20,0 - 24,0

C 19,0 - 25,0

Open space office 1,0 1,2

A 21,0 - 23,0

B 20,0 - 24,0

C 19,0 - 25,0

Cafe,restaurant

1,0 1,2

A 21,0 - 23,0

B 20,0 - 24,0

C 19,0 - 25,0

Shopping center 1,0 1,6

A 17,5 - 20,5

B 16,0 - 22,0

C 15,0 - 23,0

Housing 1,0 1,2

A 21,0 - 23,0

B 20,0 - 24,0

C 19,0 - 25,0


ČSN EN 16798-1ENERGY PERFORMANCE OF

BUILDINGS – VENTILATION FOR BUILDINGS –

PART 1: INDOOR ENVIRONMENTAL INPUT

PARAMETERS FOR DESIGN AND ASSESSMENT OF

ENERGY PERFORMANCE OF BUILDINGS

ADDRESSING INDOOR AIR QUALITY, THERMAL

ENVIRONMENT, LIGHTING AND ACOUSTICS –

MODULE M1-6 (8/2020)


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TIE 2122ZS

ČSN EN 16798-1

Indoor environmental input parameters for

design and assessment of energy performance

of buildings addressing indoor air quality,

thermal environment, lighting and acoustics.

• Valid since 8/2020

• The standard specifies how to identify and

define the main parameters that are used as

input for calculating the energy performance of

the building and long-term assessment of indoor

environment.

180prof. Karel Kabele, CVUT 180

Thermal comfort

• ČSN EN 16798-1– parameters for the thermal comfortassessment in buildings with different building servicessystems.

• Parameters useable for building energy performance calculations

• IAQ, thermal environment, lighting, acoustics

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Category Explanation

I High level of expectation and is recommended for spaces occupied by very sensitive persons (very young children, sick, elderly persons,...)

II Normal level of expectation for new buildings and renovations

III An acceptable, moderate level of expectation, for existing buildings

IV Acceptable for a limited part of the year


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Thermal comfort

• Boundary conditions for the design of mechanicaly

heated and cooled buildings

Building type CategoryOperative (resultant) temperature (°C)

Minimum for heating Maximum for cooling

Single office (cellular office)

Sedentary ~ 1,2 met

I 21 25,5

II 20 26

III 19 27

Category of indoor thermal environment

Thermal state of the body as a whole

PPD PMV

I 6% − 0,2 < PMV < + 0,2

II 10% − 0,5 < PMV < + 0,5

III 15% −0,7 < PMV < + 0,7

IV >15% 0,7 < PMV PMV < - 0,7


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Example of assessment of parameters of

indoor environment

184

Source:ČSN EN 16798-1


Adaptive model of Thermal Comfort

operative temperature °C;

moving average outdoor air temperature in ° C;

Default design values of

operating temperature for

buildings without

mechanical cooling as a

function of the moving

average outdoor air

temperature

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• Footprint - internal temperature during

the whole year.

◼ Footprint –working hours7-17h.

185Source: ČSN EN 15251

Example of assessment of parameters of indoor environment


Assessment of thermal comfort

• Operative temperature tg

(C)

• Radiant temperature asymetry tr

(C)

• operative air temperature

differences in the level of head and ankles t

o(C)

• Air velocity va

(m.s-1)

• intensity of radiation I (W.m-2)

• Relative humidity rh (%)TIE 2122ZS prof. Karel Kabele, CVUT 186

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Subjective

assessing physical environments


ISO 10551:2019(E)

Subjective

assessing physical environments


ISO 10551:2019(E)

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Literatura

• Jokl Miloslav: Zdravé obytné a pracovní prostředí, Academia Praha 2002, ISBN 80-200-

0928-0

• Bluyssen Philomena M.: The Indoor Environment Handbook - How to Make Buildings

Healthy and Comfortable, Earthscan Ltd (United Kingdom), 2009, ISBN-13:

9781844077878

• Rehva guidebook 6: Wargorcki (ed.), O. Seppänen (ed., J.Andersson, A. Boerstra, D.

Clements-Croome, K. Fitzner, S.O. Hanssen: Indoor climate and productivity in offices.

• Rehva guidebook 13 : F.R. d´Ambrosio Alfano (ed.), L. Bellia, A. Boerstra, F. van Dijken,

E. Ianniello, G. Lopardo, F. Minichiello, P. Romagnoni, M.C. Gameiro da Silva: Indoor

environment and energy efficiency in schools - Part 1 Principles

• Rehva guidebook 14: Indoor climate Quality Assessment, 2011, ISBN 978-2-930521-05-3

• CIBSE: Guide A: Environmental design, ISBN: 1903287669

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125 tie thermal comfort ii - cvut.cz

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