06.01 General

Categories: Building Comfort

Introduction
The term ‘comfort’ has a broad definition; however when related to the built environment it refers to a state of mind that expresses satisfaction with that environment. It can be divided into four sub-headings, each representing a different environmental stimulus:

Thermal comfort, Section 06.02

Visual comfort, Section 06.03

Acoustics, Section 06.04

Olfactory comfort, Section 06.05

Each person has different expectations for comfort and their sensory systems are aroused in different ways. This may be for a number of reasons such as the individual’s psychology, metabolism, age, or simply their susceptibility to certain conditions, e.g. people who are resident in hot countries have a different perception of comfort to those who live in cold countries.

The variable nature of people’s sense of comfort is such that it will be rare that all occupants can be satisfied at all times. Therefore there is no simple set of conditions, which can be defined as being comfortable, but rather a range of conditions over which the majority of people are satisfied. The purpose of the advanced facade is to provide conditions, which remain within the defined comfort range, with a minimal use of building services.

Satisfaction with the environment could also be defined as indifference to the environment, in other words the absence of discomfort; where discomfort is alleviated by making various adjustments.  We can categorise the mechanisms man uses to alleviate discomfort into three categories:

behavioural - moving to another environment;

physiological - adapting to the environment, e.g. dilation of skin pores, control of skin hair, control of pupil size etc.;

artificial - changing the environment, the creation of tolerable or comfortable conditions where none previously existed.

Man’s development of artificial techniques for climate control, such as adaptive facade components, can be attributed to his need for an environment that enables him to thrive and flourish. This is emphasised by research which attempts to define the influence of the indoor climate on productivity, health and well being, in order to quantify the economic benefits of creating the right environment to work.  However, defining a comfort band in which all of the individuals within an environment are comfortable is very difficult.  This is because comfort is not only affected by environmental variables, it is also affected by pyschological variables too.  Therefore many researchers now believe that universal comfort can only be achieved if in addition to providing a certain comfort band in environmental conditions, the designer also provides individual control.
 

Psychological factors affecting comfort
Field studies have shown that there are a number of discrepancies in the way in which we assess environmental comfort mathematically.  One reason for these discrepancies is that any model of such an empirical nature can lead to a crude oversimplification of the interactions between people and their surroundings. The perception process is not solely governed by environmental stimuli and primary physiological responses but also by personal and contextual factors not considered by laboratory studies:

perceived control of the environment

stress in the workplace

job satisfaction

organisational structure, i.e. size of work-groups, layout of offices

expectations

past experiences

Some work has been done to try and quantify some of these psychological factors by creating what the authors called adaptive errors. These are also empirically derived variables that could be applied to correct the environmental comfort equations.

This work is the next step towards developing a new set of standards that reflect people's adaptive mechanisms. However, its empirical nature means that it cannot account for all the diversities of real world situations and individual preferences; for example, some people prefer to sit in direct sunlight and some people do not. Each person, organisation, task and climate represents a change in psychological variables as much as it does physical variables; this makes an individual's perception of comfort very difficult to predict and thus impossible to guarantee with automatic control alone.  For this reason an occupant over-ride should almost always be provided for an automated comfort control system.
 

Individual control
Design comfort criteria, by definition, are related to an average person engaged in a specific activity within a defined environment. The terms average person or "user" are neutral and completely obscure differences amongst people. Settings and environments in which office workers feel most comfortable are as varied as their individual physiologies, thus making environmental design difficult. However, there is broad agreement among researchers that individual comfort and satisfaction can be attained by providing individual control of the local environment.

The perception of being in control appears to be as important as having comfortable conditions. Perceived control depends on the presence, design and placement of control devices, but also on the overall effectiveness of control strategies, the attitudes and actions of the management and the way in which physical and human management systems operate together.

Despite such advice, designers continue to build essentially static buildings that are centrally controlled and unable to be fine tuned by individual users. These buildings produce environments of moderate quality that can leave a percentage of the occupants dissatisfied and sometimes ill. We continue to use the design standards which knowingly are unable to respond to 20-30% of the building’s population in terms of environmental comfort and well-being.  The design challenge lies in integrating the users’ priorities with energy efficient control, so that their actions are coincident with behaviour that conserves energy.