Module 6

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Module 6
Post occupancy evaluation and thermal comfort
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Plan

• Post Occupancy Evaluation
• Case of Study SARA project
• Questionnaire model

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POE - POST OCCUPANCY EVALUATION

• Technically, POE studies of buildings involve
  systematic collection and evaluation of
  information about the performance of a building
  in use. Data collected can include measured
  information such as energy consumption,
  temperatures, lighting levels, acoustic
  performance etc., and survey data from the
  perspective of the occupants regarding issues
  such as comfort, aesthetics, occupant
  satisfaction, management, etc ..
• Gupta, R. (2006) Learning by doing a
  post-occupancy building evaluation module for
  postgraduate architecture students

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POE FSTC (1)

• The POE (Post Occupancy Evaluation) is concerned
  with the performance of the building (the
  building is often hot in summer).
• the FSTC (Field Studies of Thermal Comfort) is
  concerned with the occupant of the building (I
  feel hot now).
• The function of the occupant in the POE is to
  provide a subjective measure of a building and
  act as its memory

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POE FSTC (2)

• The POE survey puts little emphasis on measuring
  the physical characteristics of the environment
  (temperature etc) at the time of the evaluation
• In the thermal comfort survey the physical
  measurements are a key function because the aim
  is to predict the subjective from a knowledge of
  the physical.

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POE FSTC (3)

• The FSTC is uses detailed experimental work done
  in laboratories and climate chambers to explain
  the physiological and physical and psychological
  processes which underlie thermal comfort
• In the same way POE can be informed by the
  results of FSTC which explore the responses of
  building occupants

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POE FSTC (4)

• There is a rich interface between the two types
  of survey and the ways in which they complement
  each other.
• In particular the ways in which the information
  from comfort surveys might be of use to explore
  the subjective scales in a POE, both as regards
  their design and interpretation

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Thermal comfort

• Thermal comfort is famously described by ASHRAE
  Standard 55 as that condition of mind which
  expresses satisfaction with the thermal
  environment.
• A Psychological phenomenon not a physiological
  one (though with a base in physiology and physics)

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The lessons of comfort surveys (1)

• Field studies in buildings show that the
  subjective response is the driving force behind
  the behavioural reaction according the adaptive
  principal
• If a change occurs such as to produce
  discomfort, people react in ways which tend to
  restore their comfort.

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The lessons of comfort surveys (2)

• Comfort is not just a response to thermal
  conditions, but part of an interaction between
  occupants and buildings
• Comfort is a goal to be sought from, not a
  product delivered by the building
• The occupants may change themselves, or use
  controls to change the condition to achieve
  comfort

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Comfort is achieved by the occupants adapting to
the building
Occupant
Building
Or by the occupants adapting the building to suit
them
This has to be done within the climatic, social,
economic and cultural context of the whole system
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Adaptive opportunity

• Crucial, therefore, to the likely success of any
  building in being comfortable are the adaptive
  opportunities it provides.
• Adaptive opportunities are those features of the
  building which allow the occupants to adapt
  themselves to the building or to adapt the
  environment in the building to their own
  requirements

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Personal Variables
Data from Pakistan
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The result of these actions is shown in this
graph of the level of discomfort at different
indoor temperatures among office workers in
Pakistan
Little discomfort
Source Nicol, Raja, Allauddin Jamy (1999)
Energy and Buildings 30
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Different controls are used in different
circumstances
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People adapt

• Over time the temperature which people find
  comfortable is close to the mean temperature they
  have experienced.
• In other words the conditions which occupants
  find comfortable are influenced their recent
  thermal experience.

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Results from field surveys
Source From Nicol Humphreys Energy and
Buildings 34
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Thermal indices

• Much of the work in thermal comfort (laboratory
  and field) has been aimed at perfecting an
  index to describe comfort in terms of all the
  environmental and personal factors effecting
  comfort
• PMV, ET, SET etc

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Thermal indices

• The problem with complex indices is not only how
  to collect the data, but also that the errors,
  both in the measurement of the variables and in
  the way they are put together, tend to be
  cumulative.
• The more complex the index the more important the
  errors and the less the likelihood that the index
  will be useful as a predictive tool.

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Variability and forgiveness (1)

• When occupants describe conditions as hot, they
  often mean hot as compared to what might be
  expected or hot as compared to what I normally
  expect.
• This might imply the deviations from the normal
  temperature would give rise to dissatisfaction
  and that variability leads to discomfort.

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Variability and forgiveness (2)

• But temperature change in buildings might be the
  result of occupant actions to achieve comfort as
  well as the result of factors beyond their
  control.
• Variable temperatures (assumed to be a bad
  thing in the steady-state heat balance models of
  thermal comfort) might actually be improving
  occupant comfort.

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Variability

• Change is natural, stasis is only possible in
  certain (generally non-sustainable)
  circumstances.
• Thermal sensation relates to a running mean of
  temperature rather than its instantaneous.
• The relationship is not an exact one but the
  principle seems robust over a number of studies.

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Running mean temperature

• The rate at which the comfort temperature
  changes is related to the running mean of the
  outdoor temperature (red line)

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Wilson Building, Open University, UK Passive
refurbishment of first floor studio
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Third floor Passive studio
August 1995 (weather very hot)
How often is it too hot?
September 1995
October 1995
Never Often Never
Often
Source POE research team at OBU
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Source POE research team at OBU
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OU Studio

• Perception of building changes with the outdoor
  conditions
• Overall satisfaction with passive Studio floor is
  better
• (also satisfaction better near window than away
  from it)

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2. Case of study SARA Project
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In the UK the chosen project was of the new
Administrative and Student Services Building
(ASS), Southampton University. With 2500 m2 gross
area this new department building, located on the
existing campus site, comprises of a new 3
storeys high block linked to the old
administrative block by an atrium.
Description of the UK building of SARA Project
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State of project progress
SUMMER 2006
SUMMER 2006
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SUMMER 2006
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SUMMER 2006
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SUMMER 2006
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SUMMER 2006
SUMMER 2006

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SUMMER 2006
SUMMER 2006

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SUMMER 2006
SUMMER 2006

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SUMMER 2006
SUMMER 2006
WINTER 2006

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SUMMER 2006
SUMMER 2006
WINTER 2006

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SUMMER 2006
SUMMER 2006
WINTER 2006

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WINTER 2006
WINTER 2006
SECOND, THIRD AND FORTH FLOORS OF NEW
BUILDING
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SECOND, THIRD AND FORTH FLOORS OF NEWOLD
BUILDING
SECOND, THIRD AND FORTH FLOORS OF NEWOLD
BUILDING
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SECOND, THIRD AND FORTH FLOORS OF NEWOLD
BUILDING
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WINTER 2006
SECOND, THIRD AND FORTH FLOORS OF NEWOLD
BUILDING
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WINTER 2006
WINTER 2006
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WINTER 2006
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WINTER 2006
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WINTER 2006
WINTER 2006
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Concluding remarks

• Building performance required fine tuning for
  design, fabric and services
• Users performance participation and information

A demonstration project co-financed by the
European Commission. (TREN/04/FP6EN/S07.31838/5031
88)
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Conclusions (1)

• Surveys, whether of buildings or of people, form
  part of a continuum.
• The climate chamber thermal comfort study might
  sit at one end and the POE at the other.
• The FSTC stands somewhere in between and must
  learn from and inform both.

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Conclusions (2)

• The FSTC is concerned with the physics and
  physiology of the climate chamber study but not
  constrained by the implied image of humans as
  animals with clothes.
• At the same time because the context of the FSTC
  is almost always a building, the findings of
  field studies will often touch closely on the
  evaluation of buildings

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Conclusions (3)

• Thermal comfort is a goal of building occupants
  and not simply a product of the building
  services, though the building services provide
  some of the means by which the goal is achieved.
• Buildings and their occupants interact
  continually and the relationship between them is
  a dynamic one.

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Conclusions (4)

• The use of building controls should be a concern
  for future energy research
• In using occupants as part of the means to
  measure buildings, POE should understand the
  changing nature of the comfort the occupants
  are being used to measure.
• This has profound implications for the
  reproducibility of the POE survey results.

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3. Questionnaire model

• Used in the framework of the SARA project

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