CIBSE TM52 Overheating Assessments

To generate CIBSE TM52 overheating reports use the corresponding selection on the Output tab of the Simulation options dialog. When this option is selected DesignBuilder uses the EnergyPlus EMS system to provides custom TM52 outputs in the eso file for review in the Results Viewer. You can see some example TM52 output at the bottom of this page.

Criterion 1: The first criterion sets a limit for the number of hours that the operative temperature can exceed the threshold comfort temperature (upper limit of the range of comfort temperature) by 1 K or more during the occupied hours of a typical non-heating season (1 May to 30 September).
Criterion 2: The second criterion deals with the severity of overheating within any one day, which can be as important as its frequency, the level of which is a function of both temperature rise and its duration. This criterion sets a daily limit for acceptability.
Criterion 3: The third criterion sets an absolute maximum daily temperature for a room, beyond which the level of overheating is unacceptable.

A room or building that fails any two of the three criteria is classed as overheating. Further information on these criteria can be found in TM52: 2013, Section 6.1.2.

Important Note: CIBSE TM52 outputs are only generated for zones without active cooling.

DesignBuilder automatically excludes results from unoccupied periods and from periods in the heating season (October - March).

Procedure:

Select appropriate DSY hourly weather data.
Select the CIBSE TM52 output option.
Select the Building category I-III, using guidance from the table below.

Building Category	Explanation	Suggested Acceptable Range (K)
I	High level of expectation only used for spaces occupied by very sensitive and fragile persons	2
II	Normal expectation (for new buildings and renovations) - CIBSE recommendation	3
III	A moderate expectation (used for existing buildings)	4

Run the simulation for at least the period 1 May - 30 September.
Open either the .eso or .drb output file using the Results Viewer.
Access summary results on the CIBSE TM52 tab as explained in Example TM52 Outputs below.

For example:

Criterion 1 is passed in Block1:Zone1 if RunPeriod output Block1:Zone1 Criterion 1 CIBSE_TM52 has a value of 0.03 or less (i.e. it must be <= 3%)

Criterion 2 is passed in Block1:Zone1 if no Daily output Block1:Zone1 Criterion 2 CIBSE_TM52 has a value of greater than 6.

Criterion 3 is passed in Block1:Zone1 if RunPeriod output Block1:Zone1 Criterion 3 CIBSE_TM52 has a value of 0. A value of zero indicates that the Delta T does not exceed 4K.

Note: 2 out of the 3 criteria must be passed for an overall pass for the zone.

Tip: You can generate T_Max adaptive comfort and the deltaT intermediate values used in the TM52 calculations by selecting timestep outputs as well as TM52 outputs. These outputs can be viewed in the Results Viewer along with the other TM52 outputs. TMax CIBSE_TM52 is the name of the report for the maximum adaptive comfort temperature.

Example TM52 Outputs

When you open an eso file in the Results Viewer that includes TM52 results, an extra CIBSE TM52 tab is displayed. Clicking on this tab reveals the summary TM52 results grid as shown below.

Weather data

DSY weather data for the nearest location should be used for TM52 simulations. The guidance does not specify which DSY files should be used.

Tip: You can obtain CIBSE Current and Future weather files suitable for use in TM52 analyses from the DesignBuilder CIBSE weather file page.

The DSY weather data files required for the simulations can be imported using the approach described on the Add new hourly weather data help page.