Temperatures explained

Yearly chart

The annual graph allows the different months' dry-bulb temperature ranges to be evaluated. Moreover, overlaying the average value trend for each day helps visualize the differences between the minimum and maximum daily values for the investigated location.

Comfortable temperature ranges for 80% and 90% of the population, calculated according to ASHRAE adaptive comfort, are overlaid (see also the excellent CBE Thermal Comfort Tool). For each location, it is therefore possible to assess the temperature difference between outdoors and comfort conditions, or to evaluate passive free cooling strategies using outside air in the summer season. For more information on natural ventilation potential, see the dedicated page.

Annual dry bulb temperatures trend in four common climatic conditions: hot dry, tropical, temperate, and continental

Building design must inevitably consider local climatic trends. Comparing the different annual trends in the previous image, keeping the comfort zone as a fixed reference point, it is very clear that we expect to find four aesthetically and functionally dramatically different buildings.

Daily chart

Monthly scatterplots show all hourly temperatures. The temperature excursion is much more evident than in the annual graphs. Daily medians, i.e., the most frequently occurring values, help evaluate the outliers.

Daily dry bulb temperatures trend in four common climatic conditions: hot dry, tropical, temperate, and continental

Typical monthly days show what buildings must provide to create comfortable environments. Below is an example of a comparison between four drastically opposite climates

Overall, the first observation is the climatic variability of desert and continental climates, while the other two are mostly stable at constant levels.

More in detail, imaging that we might design a building, we start from the factual need to reduce incoming heat into the environment with solar shading or other passive solutions in desert climates, to the constant need to create air movement that gives a sense of coolness in the constant tropical climates; we get to the steady temperate climates where it is easier to recreate comfortable conditions, to the continental climates, which are highly variable from summer to winter and certainly more challenging to handle.

Heatmap

Heatmap is another useful method for evaluating thermal excursion over a year (by evaluating the horizontal gradient) or over individual days (by evaluating the vertical gradient).

Daily dry bulb temperatures heatmap for four common climatic conditions: hot dry, tropical, temperate, and continental

Albeit with different scales, the four heatmaps give a clear idea of the comparison of the four given climate types, especially for the temperature excursion between day and night.

• the desert climate, despite having a scale with a large delta T, shows clear contrasting vertical gradients, thus between day and night temperatures;

• the tropical climate has no variability throughout the year, with a nearly constant pattern. The same observation can be made for daily and nighttime temperatures;

• the temperate climate shows a certain constancy between day and night, but especially a slight increase over the summer month temperatures;

• the continental climate has a highly variable temperature scale, but despite this, there is a clear gradient between the winter and summer months. The difference between day and night is not clear but, as already evident in the daily graphs, the patterns are not regular and show a very variable climate.

Descriptive statistics

The last tool for temperature assessment is the statistics table. The earlier graphically made evaluations can be supported by the numbers. The following are listed, for each month:

• the temperature means;

• the standard deviations;

• the minimum values;

• the percentiles values (1%, 25%, 50%, 75%, 99%);

• the maximum values.

Descriptive statistics of dry bulb temperatures trend in a temperate climate, Berkeley (USA)