CHAMBERS FOR TRANSMITTANCE TESTS
Measuring the thermal behaviour of building components is crucial to comply with the increasingly stringent EU directives on energy performance.
ACS transmittance test chambers are used to measure the thermal behaviour of components, generally building components, in winter and summer under stationary and dynamic climatic conditions.
The focus here is on insulation, i.e. the thermal insulation of buildings. With this family of machines, it is possible to numerically quantify the ability of a structure to minimise heat transmission from the inside to the outside during winter and vice versa during summer. The higher the capacity of a building to thermally insulate, the lower the energy consumption of fuel or electricity.
It is therefore a highly relevant instrument with respect to environmental sustainability issues and is especially related to some recent directives of the European Council concerning the energy performance of buildings.
The Energy Performance of Building Directive (EPBD), approved on 12 April 2024 by the European Parliament is, together with the Energy Efficiency Directive, the main legislative instrument to promote the energy performance of buildings to help reduce greenhouse gas emissions and energy shortage in the EU. Buildings currently account for more than one third of greenhouse gas emissions in the EU.
In addition, a revision more widely known as the Green Directive came into force on 29 May 2024 to accelerate the energy efficiency of the existing assets and Member States will have until 29 May 2026 to comply. The Green Directive requires each EU member state to commit to the implementation of a new building refurbishment plan, taking measures to ensure a reduction in the average primary energy used by residential buildings.
ACS transmittance test chambers can give a fundamental contribution to the search for materials and solutions enabling the steps dictated by these new directives, by measuring real performance under reproducible environmental conditions in the laboratory.
As with calorimeters, transmittance test chambers consist of two different environments, one simulating the internal conditions of a house or building, the other reproducing all possible external climatic conditions. In between, a frame is fitted with dimensions of up to approximately 3x3m, which can be produced on request in several variants to accommodate different types of walls both in shape and thickness, so as to replicate different environmental conditions on the two faces, with a temperature difference of at least 20°C and air speed parallel to the surface, adjustable from a minimum of 0.1m/s up to 10m/s.
Transmittance test chambers are an essential tool for assessing the environmental sustainability of buildings: depending on the desired functionality, it is possible to test elements of a building (walls, glazing, doors, windows) in relation to a large number of external factors, such as temperature, humidity, wind, rain, solar radiation, and internal factors such as temperature, humidity, natural and forced air convection, vapour and air permeability. In special cases, through the application of specific solutions and instruments, it is possible to provide very low heat flux measurement on walls made of highly insulating materials with thermal transmittance in the range of 0.05 W/m²K.
ACS and the quality of our homes: La Rochelle University studies on building envelopes
The Laboratory of Engineering Sciences for the Environment is using an ACS calorimeter for thermal transmittance tests to assess the performance of building envelopes in a controlled environment, both for construction and renovation of buildings.
For this purpose, the LaSIE laboratory has equipped itself with one of the products in the ACS climatic chamber range, the calorimeter for thermal transmittance tests. This is a calibrated double chamber for characterising the thermal and water performance of the envelope components and can accommodate wall samples measuring 2.2 x 2.2 m and up to 45 cm thick. Temperature (-20°C to 45°C), humidity (5% to 95%) and pressure (0 to 40 Pa) conditions can be imposed on both sides of the samples. Two configurations are provided: protected hot chamber operation (temperature control) and dual chamber operation (temperature, humidity and/or pressure control).
The calibrated dual chamber is a reliable instrument that can be adapted to a wide variety of conditions. Under static conditions, tests can be carried out quickly, repeatably and with high accuracy thanks to appropriate metrology.
The advantage of the ACS chamber lies in its ability to independently control the three important heat transfer variables of temperature, humidity and pressure. Finally, dynamic conditions characteristic of real environments can be reproduced to allow better estimation of in-situ wall performance.
La Rochelle also chose our chamber for its advanced test management and technical implementation solutions that enable a wide range of measurements.
This has allowed the University to dedicate the calorimeter to three types of activities:
- research projects in collaboration with the LaSIE laboratory dealing with hygrothermal transfer issues
- tests as part of services to support the development of innovative products for the envelope
- projects intended for institutional structures for the purpose of control or expert opinion on works.
Controlling the pressure between the two chambers also provides an additional benefit: observing the influence of this parameter on hygrothermal transfers and better assessing the influence of permeability on the envelope performance.
"The ACS calorimeter is a high-quality piece of equipment, which allows precise control of the two chambers and obtains repeatable measurements. In addition, it is possible to integrate specific metrology for each test in order to meet the needs of research projects. Finally, the proximity of ACS France's local staff ensures a reasonable response time in the event of a malfunction."
