Dynamic Thermal Modelling


Thermal Modelling by Dynamic Simulation, or Dynamic Thermal Modelling, is becoming more common to demonstrate the way a building will behave during summertime in terms of overheating and whether sufficient fresh air can be obtained when a naturally ventilated solution is preferred to mechanical ventilation.

In the same way building design has progressed over the years, so have the standards that govern them, Building Regulations have become more stringent and new environment standards have been introduced such as Breeam and LEED. Local governments also stipulate their own requirements to be met such as the London Plan (www.london.gov.uk/what-we-do/planning/london-plan)

CIBSE TM59 Overheating

CIBSE TM59: Design methodology for the assessment of overheating risk in homes sets the standards which need to be met specifically for residential property.

Overheating risk has been a growing concern amongst the domestic design, construction and provider community for at least a decade. Domestic overheating has not always been a problem in the UK but climate change, increased urbanisation, construction of high-rise apartment blocks and winter energy efficiency measures have all contributed in the amplification of high internal temperatures. Homes that overheat cause significant discomfort and stress to the occupants and can ultimately lead to litigation and costly mitigation measures for the owners/developers.

Compliance is based on passing both of the following two criteria:

  1. For living rooms, kitchens and bedrooms: the number of hours during which DT is greater than or equal to one degree (K) during the period May to September inclusive shall not be more than 3 per cent of occupied hours. (CIBSE TM52 Criterion 1: Hours of exceedance).

  2. For bedrooms only: to guarantee comfort during the sleeping hours the operative temperature in the bedroom from 10 pm to 7 am shall not exceed 26 °C for more than 1% of annual hours. (Note: 1% of the annual hours between 22:00 and 07:00 for bedrooms is 32 hours, so 33 or more hours above 26 °C will be recorded as a fail).

  3. Criteria 2 and 3 of CIBSE TM52 may fail to be met, but both (a) and (b) above must be passed for all relevant rooms.

Contact L2 Energy Consulting for CIBSE TM59 calculations to ensure overheating in new homes will not be a problem.


BB101 (Building Bulletin issue 101)

Rules have also been introduced for different building types, such as the Building Bulletins for Educational Buildings (BB101).

These adopt adaptive thermal comfort methodology outlined in CIBSE TM52. (for more information see our BB101 specific page)


BREEAM (Building Research Establishment’s Environmental Assessment Method)

BREEAM HEA04 Thermal Comfort also adopts CIBSE TM52: The limits of thermal comfort: avoiding overheating in European buildings.


At L2 Energy we can help to demonstrate Dynamic Thermal Modelling requirements through dynamic simulation software. Please call us on the number above, or ask for a quote electronically.