1. Stages of the validation process
The thermal validation process consists of applying heating power to the building over a period of time, measuring its thermal response, and comparing the response to what we would expect to see on the basis of the design data.
- Preparation: The preparation stage consists of preliminary calculations and planning the measurements to be carried out
- Measurements: The measurement stage consists of measuring the temperature inside and outside the building while it is heated, and then left to cool.
- Validation calculations: The validation calculations produce a range of heat loss coefficients for the building that are consistent with the measured data. This range is compared with the building’s design data or relevant building standards.
2. Complicating factors
Many factors contribute to the thermal response. These will need to be either avoided in the experiment, included in the model, or a combination of the two.
We have carried out an exhaustive series of experiments on this idealized example structure. Although carried out indoors, we have attempted to change conditions by running at lower heat power and making deliberate leaks and weaknesses in the structure. This shows that this method correctly finds:
- The accepted value of 2.73W/K
- A significant increase in heat loss value when materials are substituted
- An increase in heat loss value when defects such as cracks, thermal bridges and holes are present.
- The same value when thermal mass is added.