What is a bioclimatic chart?

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An architect or Heating Engineer might create a bioclimatic chart when planning a new building. It is a graphical representation of the environmental conditions in a location where a building project is destined to commence.

The idea is that measurements of the climate during the course of a year will enable planners to adjust the design of the building and its services to ensure that the conditions inside the building are bearable.


The bioclimatic chart was invented by a Hungarian architect called Victor Olgyay. He produced the first chart in 1963 to illuminate his specialisation of “climate sensitive design.” Olgyay plotted the humidity and temperature of a location on a graph. He then deduced a “comfort zone” within the temperature and moisture data which would enable occupants of the building under consideration to go about their business unhindered by adverse environmental conditions.


Olgyay’s work was carried on by Professor Baruch Givoni who refined the bioclimatic chart to include zones displaying the outcome of possible design strategies. The Givoni chart contains the comfort zone, marked by a solid line and then four zones one for each alternative strategy under consideration. The strategy outcomes are depicted with broken lines.


The bioclimatic chart required a year's worth of environmental data. Olgyay’s original chart focused on humidity versus heat. Givoni’s studies include measuring a number of other factors, to create different charts. He measured things like the level of perspiration on a subject in a given environment.


UK planning laws do not require bioclimatic charts as part as a submission for planning consent and so they are not common practice in mainstream architecture in this country. Most implementations of the charts are undertaken as part of academic dissertations. Although source data can be obtained from local weather stations, the requirement to gather environmental data over a year makes the charts expensive to compile if they relate to the interior of an existing building or if the proposed site has specific conditions that do not emerge in a nearby location where existing meteorological monitoring is undertaken.


The future of bioclimatic charts remains with the types of organisations that currently use them. That is, niche architectural practices and not-for-profit bodies concerned with ecological issues. The environmental controls of buildings cover heating, ventilation and air conditioning. These systems are collectively known as HVAC. Planners of HVAC systems are more likely to use bioclimatic charts in support of systems known as “passive cooling” systems. These rely on the properties of building materials, the shape of the building and wind direction to cool the interior of the new building. Passive systems do not succeed for heating and so the majority of implementations of bioclimatic charts have occurred in hot, arid locations. They support an alternative construction strategy that removes the need for mechanical air conditioning by maximizing natural ventilation.