Roel C.G.M. Loonen

Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings

Electrically switchable broadband infrared reflectors that are relatively transparent in the visible region have been fabricated using polymer stabilised cholesteric liquid crystals. The IR reflectors can change their reflection/transmission properties by applying a voltage in response to changes in environmental conditions. Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector. We have also fabricated a switchable IR reflector which can also generate electricity. These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy.

Application of broadband infrared reflector based on cholesteric liquid crystal polymer bilayer film to windows and its impact on reducing the energy consumption in buildings

An infrared (IR) polymer reflector based on chiral nematic (cholesteric) liquid crystals has been fabricated which can reflect more than 60% of solar IR energy without interfering with the visible solar radiation. Simulations show that the polymer bilayer film applied to a window of a typical building can have a significant impact on the interior temperature in living and working spaces.

Review of current status, requirements and opportunities for building performance simulation of adaptive facades†

Adaptive building envelope systems have the potential of reducing greenhouse gas emissions and improving the energy flexibility of buildings, while maintaining high levels of indoor environmental quality. The development of such innovative materials and technologies, as well as their real-world implementation, can be enhanced with the use of building performance simulation (BPS). Performance prediction of adaptive facades can, however, be a challenging task and the information on this topic is scarce and fragmented. The main contribution of this review article is to bring together and analyse the existing information in this field. In the first part, the unique requirements for successful modelling and simulation of adaptive facades are discussed. In the second part, the capabilities of five widely used BPS tools are reviewed, in terms of their ability to model energy and occupant comfort performance of adaptive facades. Finally, it discusses various ongoing trends and research needs in this field.

Infrared reflector based on liquid crystal polymers and its impact on thermal comfort conditions in buildings

There has been a huge increase in the global demand of energy over the last few years. One of the main contributors to energy consumption in buildings, cars, greenhouses and indoor spaces is the cooling devices needed to maintain the indoor temperature at comfortable levels. To reduce the energy used by cooling devices, we need improved light control in transparent building elements, such as windows. Infrared (IR) reflectors applied to the windows for rejection of infrared light would be very attractive, especially if they do not affect light in the visible region. A method to selectively and precisely control infrared transmission is via the use of cholesteric liquid crystal (Ch-LC) polymer reflectors. Ch-LCs, also known as chiral-nematic LCs, reflect circularly polarized light as a result of their self-organizing molecular helices. The pitch of the helix in these networks determines the wavelength of reflection. In contrast to existing alternatives, they are characterized by a very sharp cut-off between the transmissive and the reflective state enabling exact tailoring of the heat reflection. In this article we have focused on fabrication of infrared reflectors using Ch-LCs and a computational model was used to predict the energy savings of this IR-reflector in an office building in Abu Dhabi which indicated that 6 % energy savings can be realized.