Week 1b: IEQ, IAQ, thermal comfort

IEQ

Indoor environmental quality

IAQ

Indoor Air Quality

To what value driver is the IEQ most related

User/Basic value

Four physical aspects of IEQ

1. Thermal

2. Air quality

3. Aural (sound)

4. Visual

IEUQ influences

1. Health, Comfort, Performance

2. Energy demand

3. Circularity

How much of the energy used in buildings is going to IEQ?

More than 60%

HVAC

Heating, ventilation and air conditioning

KIPI framework: Performance indicators

1. Health and comfort

2. Safety and security

3. Usability and positive stimulation

4. Adaptability and serviceability

What is a building decree

Performance requirements that buildings should adhere to

What are the names of the guidelines

ISO (international), ASHRAE (international), ISSO (Netherlands)

The Program of Requirements with performance requirements are developed for four types of buildings:

1. Healthy offices

2. Fresh schools

3. Healthy dwellings

4. Long term care facilities

What are the three levels/classes of the PoR

C: Building decree

B: Better quality for health and comfort

A: High quality, (for dwellings) focused on special groups

Verification of PoR healthy dwellings

1. Low level at hand-over

2. Long-term with sensors

3. Detailed measurements in response to complaints

What are the tools to assess the performance of buildings

1. BREEAM from 1990 about Environmental sustainability

2. LEED from 1998 about Environmental sustainability

3. WELL from 2014 about health & comfort

What is the difference between BREEAM/LEED and WELL:

Balance energy demand vs IEQ

What are the three questions to evaluate thermal comfort

1. How are you feeling now (range from very cold to very hot)

2. Do you find this (range comfortable to very uncomfortable)

3. How would you prefer to be now? (range much cooler to much warmer)

What is the missing word

Adaptation

What should the internal body temperature be

37

How can we change the core temperature

Widening or narrowing the blood veins in order to keep warmth or lose warmth and sweating

What factors in our environment affect heat (loss)

Humidity, air velocity, air temperature, activity, mean radiant temperature, temporal nature of exposure

How do we adapt for warm discomfort

Rate of sweating

How do we adapt to cold discomfort

Skin temperature

What is the right temperature

Ask through survey for a group of people

How to design with thermal comfort in mind

1. Heat balance approach (a method for the calculation of steady state thermal comfort obtained from climate chamber research)

2. Adaptive approach: a relation for steady state thermal comfort derived from studies in the field

Heat balance approach formula

H - Edif - Esw - Eres - Cres = R + C (metabolism/internal heat production - evaporation diffuse - evaporation sweat - evaporation respiration - convection respiration = radiation + convection

How did Fanger experiment for the Heat Balance Approach formula

Expose subjects to environmental conditions, measure conditinos and ask perceived thermal sensation

PMV model

Predicted mean value

T mrt in the heat balance approach formula

Average temperature of all the objects in the room

Remarks from PRV model

• Often T air and T mrt assumed equal

• T operative = (Tair + Tmrt)/2 (because it defers per location in the room)

• Air speed low

• Color bands (green): three classes standard

What is a conclusion that can be drawn from this image about humidity, clothing and metabolism

Metabolism and clothing are much more sensitive as compared to relative humidity

Three levels of types of adaptation in the adaptive approach regarding thermal comfort

1. Behavioural

2. Psychological (change in sweating rate and vasomotion)

3. Physiological (if your expectations were not correct, you are more likely to be furstrated)

Test for adaptive approach for thermal comfort

Global field study on the relation between thermal comfort and temperatures. Implicitly assumed that adaptation has taken place

a

a

Asymmetric thermal comfort in a room examples

Asymmetric radiant fields, vertical air temperature gradient, warm or cold floors, draught

Draught risk =

percentage dissatisfied

Turbulence intensity formula

TI = 100* (vstdev/vmean)

Which one of the approaches should be used when the building is not actively cooled

Adaptive model (or requirements Healthy Dwellings)

Design consideration for behavioural adaptation

Openable windows, thermostats, curtains, local heating or fans

Design consideration for physiological adaptation

Allow variation in temperature

Psychological adaptation

Let temperature changes be understandable for the occupants on the basis of the type of building and outside temperature

Main concepts this lecture:

• Thermal comfort models

  • Heat balance approach (Predicted Mean Vote)

  • Adaptive approach > types of adaptation

• Asymmetric (non-uniform) thermal conditions

Types of contamination

Human body, human activities, furniture, outdoor

Reduce air contamination

1. Remove source when possible

2. Ventilate

What is infiltration

Air ‘ventilation’ through leakages

Formula contaminent concentration inside

Ci = Ce + M/V (contamination concentration external + source strength / air volume flow)

What is good or bad

WHO global air quality guidelines

Why do we measure CO2 concentration as measure for air quality

• Is produced at a known rate by humans

• In many cases most important sources

Dutch Building Decree assumes a CO2 concentration of (…) ppm as sufficient

1200 (other say 900, 750)

What is a note on using CO2 as indicator

• CO2 and other contaminations in itself is not regarded a contaminant that affects health, but gives indication of bad ventilation

• Outdoor CO2 is around 450 (so presence of persons results in an extra concentration of 1200 - 450 = 750ppm)

What are the assumptions for determining the minimum ventilation flow rate?

• All contamination sources limited as much as possible

• Humans most important source of CO2

• Required ventilation flow rate can be determined based on required CO2 concentration

How to determine the minimum ventilation flow rate

1. Define desired CO2 concentration

2. Count amount of people in the room

3. Calculate using the formula

Ventilation rate for: (in dm³/s)

1. Living room/bedroom/study room

2. Kitchen

3. Bathroom

4. Toilet

1. 7

2. 21

3. 14

4. 7

Instructions for ventilation direction in dwellings

Supplied in living, bed, study room and exhausted in kitchen, bathroom and toilet.

How to ventilate

• Mixing ventilation (high in, low out)

• Displacement ventilation (low cold airco, high out)

Which graphs correspond to which ventilation?

Above mixed, below displacement

a

a

A window is not meant for ventilation, but what is it meant for

Purging (the ability to get rid of something unpleasant)

How can we measure ventilation flow rate

• FlowFinder - Measure a supply gril in m³/h

• Tracergas technique - Supply contaminant and measure concentration

Names of ventilation systems

1. Natural supply and exhaust

2. Mechanical supply, natural exhaust

3. Natural supply, mechanical exhaust

4. Mechanical supply and exhaust

Calculate risk of infection

Nc = S(1=e^(-Iqpt/V))