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ACTIS thin multifoil insulation is made up of multi-layered reflective films, only a few microns thick. These layers, which are separated by wadding, foam, sheep’s woll etc. are sewn together to form a thin insulating blanket.

It is three to five times thinner than traditional thick insulation (including air spaces) but performs to the same standard.

These products are perfectly adaptable for insulating residential, commercial and industrial buildings, in roofs, attics, walls and floors.

The strength of ACTIS insulation products is founded on the research and development of the individual components of the product and the way that they are put together.

 Thin multifoil insulation acts against all forms of thermal transfer simultaneously (radiation, conduction, and convection).

Unlike traditional thick insulation – which principally acts against thermal losses occurring via conduction – the specific nature of thin multifoil insulation, combined with its application between two air gaps, forces energy to be transmitted via radiation rather than by conduction or convection.

LEARN MORE: Forms of thermal transfer

Heat is a form of energy which is transmitted from a hot zone to a cold zone, due to temperature difference. Heat is transmitted in 4 different ways, which are also the forms of thermal loss: radiation, convection, conduction and phase change (humidity/wind).

Thermal transfer without physical contact
E.g. you can feel the heat being given off by a fire when you sit near to it.

How ACTIS insulation acts against radiation:
The external reflective foils of ACTIS insulation are extremely effective at reflecting infrared radiation back towards the source of heat (heating systems in the winter, and solar radiation in the summer). Each internal reflective foil acts as an additional barrier to thermal transfer by radiation.

Movement of warm air due to a difference in temperature and volume : hot air rises and heat dissipates.
E.g. A radiator heats the air in contact with it (conduction) and the hot air escapes upwards (convection).

How ACTIS insulation acts against convection:
Actis insulation reduces cold air infiltration in the winter, and warm air infiltration in the summer, which create thermal losses.

Heat transfer via physical contact between solids, liquids or gases.
E.g. An electric hob in contact with a saucepan transmits heat by conduction.

How ACTIS insulation acts against conduction:
The low density separators (wadding, foam, etc.) between the reflective foils of ACTIS insulation products, create insulating air gaps, which are also barriers against conduction (same principle as double glazing)
  • Outside the multifoil insulation
    Installing the multifoil between 2 air gaps – so it is not in contact with the surface to be insulated – significantly reduces thermal transfer by conduction (the only conduction occurs between the insulation and the air – which acts as an insulator).
  • Within the multifoil insulation
    Very little conduction occurs given that the foils are separated by materials which create small air gaps which act as barriers to conduction.

Heat transfer by change in physical state: solid, liquid, gas (the change from gas to a liquid state gives off heat).
E.g. condensation on the bathroom mirror is due to warm water which condenses on the cold mirror.

How ACTIS insulation products acts against phase change:
ACTIS insulation products are water resistant.

Measurement of thermal efficiency

1 / Traditional standard tests
2 / In situ measurement
3 / Dynamic fluxmeter
4 / Application for European Technical Approval

1 / Traditional standard tests

In the 1960s a model for calculating the insulation of buildings was established by the scientific community.
This model relied on using the results from tests using a guarded hot box or a guarded hot plate, laboratory equipment original created for traditional, thick, single layer insulation. This laboratory equipment measures the thermal conductivity of these products at a steady state (in other words, a constant state), this means their capacity to prevent heat loss through conduction.
The method consists of placing an insulator between two environments at different temperatures to generate a temperature difference (ΔT). Then, the amount of energy needed to maintain a constant temperature either side of the insulator is measured. Once the thermal flow has stabilised, the measurement can be made. The quantity of energy equals the thermal flow passing through the product.
Unlike traditional thick insulation – which mainly work to prevent heat exchange through conduction – the specific nature of thin multifoil insulation, combined with its application between two air gaps, forces energy to be transmitted via radiation rather than by conduction or convection. Heat exchange through conduction plays only a minor role in the way thin multi-foil reflective insulation works.

This single measurement for heat conductivity is not sufficient to categorise the overall thermal performance of thin multifoil insulation.

In other words, the current problem lies with the insulation of buildings (in line with the European Directive regarding the Kyoto agreement) and focuses on the energy consumption of buildings.
Energy consumption depends on the overall thermal performance of the insulation once it has been installed, but conventional measuring tools currently only allow for one criterion (heat conductivity) to be categorised, in laboratory conditions which are far from being similar to real-life conditions. Insulation is the effect from the insulation product installed.

1 / Traditional standard tests
2 / In situ measurement
3 / Dynamic fluxmeter
4 / Application for European Technical Approval

2 / In situ measurement

In the absence of any suitable standards, ACTIS measured the thermal performance of its products in situ, in other words in real-life conditions.

It is important to note that in real life conditions, energy is transferred in a variety of complex ways (radiation, convection, conduction). The in situ test model allows for an overall appreciation of these.

This method consisted of insulating identical and standardised buildings in different ways, and measuring, andcomparing, the energy consumption required to maintain these buildings at an identical, constant internal temperature, whatever the external weather conditions.

  • One building was fitted with a “mineral wool” (20 cm, R = 5) type of insulation, whose thermal performance was known, and accredited by the conventional methods.
  • The other building was fitted with thin multi-foil reflective insulation which ACTIS wanted to test for thermal performance.
The actual duration of the test consisted of between 12 to 14 weeks.

Example of the test buildings


The various results from in situ testing carried out on that day in different European countries (in France by the SFIRMM, in the UK by BM TRADA and in Germany by FRAUNHOFER INSTITUT FUR BAUTECHNIK) showed, across the board, that the measurements carried out in the laboratory with the guarded hot box or plate greatly disparaged the performance of thin multi-foil reflective insulation:

  • Measured under real life conditions the thermal performance of multifoil insulation is three to five times higher than when measured with the guarded hot box or plate method.
  • Measured under real life conditions the thermal performance of multifoil insulation is equivalent to traditional, thicker insulation.

LEARN MORE: the protocol for in situ tests

A very specific protocol was established for kitting out the buildings, as well as for monitoring consumption and analysing the results.

Exterior dimensions: The test buildings had external dimensions of 4 x 7 metres and an under-ceiling height of 3 metres.

Description of the structure of the test cells:
The buildings had wooden frameworks and were covered in tiles to represent a converted attic. The walls and pitches were given an internal finish of plasterboard.
There were no windows in the test buildings and the ventilation was open to the outside. Each test space was accessible through an insulated airlock in a sidewall. Heat exchange occurred through the walls insulated with the materials being tested.

Authentication and quality control:
The dimensions and exposure of the test buildings was monitored by a land surveyor.
Both the test buildings were standardised to ensure that they had the same thermal behaviour. Their energy consumption was first measured without insulation.
The buildings were then insulated and sealed before the tests began.
The mineral wool was fitted by an approved installation company, QUALIBAT, and subject to an APAVE (third party inspection agency) inspection prior to the interior facing being fitted.

Data acquisition:
Meters registered energy consumption in each of the test buildings. All the data was collected by a computer programme and analysed, taking into account any factors likely to influence consumption, such as weather data.

This methodology was certified by BM Trada, a British body accredited by the UKAS (United Kingdom Accreditation Service) and member of the EOTA (European Organisation for Technical Approval).

3 / Dynamic fluxmeter

After several years of research based on an in-depth analysis of the behaviour of insulation materials in real-life usage conditions, the R&D department at ACTIS has perfected a mathematical model which allows them to link conventional data measured in a laboratory with data measured in situ.

The mathematical model for the heat flow meter, the traditional laboratory apparatus, allows them to determine with precision the actual thermal performance of thin multi-foil reflective insulation from laboratory measurements.

This methodology has given rise to the dynamic fluxmeter, a measurement tool which includes the behaviour of insulation materials in real-life usage conditions. This tool allows for the simulation, in the laboratory, of actual thermal performances of thin multi-foil reflective insulation.

Main conclusions from the work carried out by the ACTIS Research and Development:
Download :
Thermal Reference Guide II


4 / Application for European Technical Approval

The European Directive on Construction Products (1989, OJ L106/1) has provision for a procedure allowing for the creation of new standards for innovative products: the procedure for an “Application for European Technical Approval”.
This application was introduced by the EOTA (European Organisation for Technical Approval), the European entity responsible for setting up the inquiry. The EOTA is made up of representatives from all the approved national bodies of the European Union.

In June 2003, ACTIS appointed a member of EOTA to request, on their behalf, an application for European Technical Approval for their family of products. The request for European Technical Approval was accepted by the European Commission.

By giving the green light to this request, the European Commission has recognised the innovative nature of thin multi-foil reflective insulation and its unsuitability to be considered within the scope of current test standards.

The current level of this type of scientific innovation means that the in situ method is the only one capable of measuring the actual thermal performance of thin multi-foil reflective insulation, ACTIS vigorously defends this methodology before the EOTA within the framework of their application for European Technical Approval.

In order to scientifically validate the relevance of in situ tests for thin multi-foil reflective insulation and totally independently, the EMM, the European association, of which ACTIS is a member, has suggested to the EOTA, via several of its members, that a huge research programme be launched into the in situ thermal performance of insulation materials.

This research programme consists of carrying out a series of in situ tests at several laboratories, which are members of the EOTA, in their respective countries, following the same protocol, over the same period and with identical products (a traditional thick insulation product and a generic thin multi-foil reflective insulation product), in order to be able to compare them in different climates and to obtain completely independent results.

This research programme is a specific response to the objectives set by the European Commission for materials designed to reduce energy consumption in buildings, highlighting energy consumption and supporting the actual thermal performance of the various categories of insulation material, once in placeThe EOTA (European Organisation for Technical Approval) has a process that creates new standards for innovative products. The procedure is known as an “Application for European Technical Approval” (AET).