Bjørn Petter Jelle

The Path to the High Performance Thermal Building Insulation Materials and Solutions of Tomorrow

In today’s society there is an increased focus on various energy aspects. Buildings constitute a large part of the total energy consumption in the world. In this respect it is important to have the optimum heat balance in buildings. That is, in a cold climate one wants to have as well thermally insulated building envelopes as possible. However, even in cold climates there might often be relatively long periods of overheating in the buildings, for example, due to solar heat gains and excessive heat loads from miscellaneous indoor activities. In warm climates overheating is most often the case, for example, in office work spaces with large window glass facades and extensive use of electrical equipment. Insulation retrofit is among the most cost-effective measures, even more cost-effective than, for example, solar photovoltaics. The traditional thermal insulation materials of today have typically thermal conductivities between 33 and 40 mW/(mK). State-of-the-art thermal insulation includes vacuum insulation panels (VIPs) with conductivities between 3 and 4 mW/(mK) in fresh condition to typically 8 mW/(mK) after 25 years aging due to water vapor and air diffusion into the VIP core material, which has an open pore structure. Puncturing the VIP envelope causes an increase in the thermal conductivity to about 20 mW/(mK). The main emphasis of this work centers around the possibilities of inventing and developing innovative and robust highly thermal insulating materials. That is, within this work the objective is to go beyond VIPs and other current state-of-the-art technologies. New concepts are introduced, that is, advanced insulation materials (AIMs) as vacuum insulation materials (VIMs), gas insulation materials (GIMs), nano insulation materials (NIMs), and dynamic insulation materials (DIMs). These materials may have closed pore structures (VIMs and GIMs) or either open or closed pore structures (NIMs). The DIMs aim at controlling the material insulation properties, that is, solid state thermal conductivity, emissivity, and pore gas content. Fundamental theoretical studies aimed at developing an understanding of the basics of thermal conductance in solid state matter at an elementary and atomic level have been addressed. The ultimate goal of these studies is to develop tailor-made novel high performance thermal insulation materials and dynamic insulation materials, the latter one enabling to control and regulate the thermal conductivity in the materials themselves, that is from highly insulating to highly conducting. Furthermore, requirements of the future high performance thermal insulation materials and solutions have been proposed. At the moment, the NIM solution seems to represent the best high performance low conductivity thermal solution for the foreseeable future. If robust and practical DIMs can be manufactured, they have great potential due to their thermal insulation regulating abilities.

Transmission Spectra of an Electrochromic Window Based on Polyaniline, Prussian Blue and Tungsten Oxide

The demand for energy savings in buildings will increase in the coming years, as the world`s attention is drawn towards environmental aspects and energy economizing. Windows which are able to dynamically control the sun radiation throughput will play an important role. In this respect, the authors have studied two different electrochromic window configurations; one based on the two complementary electrochromic materials polyaniline (PANI) and tungsten oxide (WO{sub 3}), the other one with the electrochromic coating Prussian blue (PB) in addition to PANI and WO{sub 3}. The inclusion of PB enhances the transmission modulation. Integrating over the solar spectrum they find that the window based on PANI and WO{sub 3} is able to regulate 39% of the total solar energy, while with the inclusion of PB they manage to regulate as much as 50% of the sun radiation.

Accelerated climate ageing of building materials, components and structures in the laboratory

Building materials, components and structures have to fulfil many functional demands during the lifetime of a building. Therefore, it is important to require satisfactory durability of these materials, components and structures. In fact, one single material failure may jeopardize whole components as well as structures. Unfortunately, experience shows that building products too often do not satisfy the various requirements after a relatively short period of use, i.e. the expected service life is considerably shorter than foreseen. This results in increased and large costs due to increased maintenance, extensive replacements of the specific building products and any possible consequential building damages. In addition, health hazards with respect to both risk and consequence may also become an issue. To avoid this, the solution is to apply building products which have properly documented adequate and satisfactory long-term durability. That is, building products which have been subjected to long-term natural outdoor climate exposure or appropriate accelerated climate ageing in the laboratory. This study examines the main climate exposures and how these may be reproduced in the laboratory in various ways. Thus, crucial properties of building products and their durability towards climate strains may be investigated within a relatively short time frame compared with natural outdoor climate ageing. Examples of miscellaneous climate ageing laboratory apparatuses, ageing methods and building product properties to be tested before, during and after ageing are given. A calculation method for estimating acceleration factors is also discussed. Various ageing examples are shown and discussed. A special note is made towards accelerated climate ageing of new and advanced materials being developed. Hence, this study addresses durability and the versatile and powerful application of accelerated climate ageing which is an all too overlooked field within materials science and engineering.

Aging effects on thermal properties and service life of vacuum insulation panels

Vacuum insulation panels (VIPs) represent a high-performance thermal insulation material solution offering an alternative to thick wall sections and large amounts of traditional insulation in modern buildings. Thermal performance over time is one of the most important properties of VIPs to be addressed, and thus the aging effects on the thermal properties have been explored in this article. Laboratory studies of aging effects are conducted over a relatively limited time frame. To be able to effectively evaluate aging effects on thermal conductivity, accelerated aging experiments are necessary. As of today, no complete standardized methods for accelerated aging of VIPs exist. By studying the theoretical relationships between VIP properties and external environmental exposures, various possible factors for accelerated aging are proposed. The factors that are found theoretically to contribute most to aging of VIPs are elevated temperature, moisture, and pressure. By varying these factors, it is assumed that a substantial accelerated aging of VIPs can be achieved. Four different accelerated aging experiments have been performed to study whether the theoretical relationship may be replicated in practice. To evaluate the thermal performance of VIPs, thermal conductivity measurements have been applied. The different experiments gave a varying degree of aging effects. Generally, the changes in thermal performance were small. Results indicated that the acceleration effect was within what could be expected from theoretical relationships, but any definite conclusion is difficult to draw due to the small changes. Some physical changes were observed on the VIPs, i.e., swelling and curving. This might be an effect of the severe conditions experienced by the VIPs during testing, and too much emphasis on these should be avoided.

Transmission spectra of an electrochromic window consisting of polyaniline, prussian blue and tungsten oxide

Abstract Energy savings in buildings can be achieved by using electrochromic windows which change colour by the application of an external voltage. We have studied an electrochromic window by combining polyaniline (PANI), prussian blue (PB) and tungsten oxide (WO 3 ) with poly(2-acrylamido-2-methylpropane-sulphonic acid) (PAMPS) as a solid organic polymer electrolyte binding the three electrochromic materials together. Transmission spectra in the 290–3300 nm wavelength region for the window at different applied potentials were recorded and show good light modulation. For instance, by applying a voltage between − 1800 and + 1600 mV, the transmission changes from 0.76 to 0.11 at 100 nm. The window is able to regulate 49% of the total solar energy.

Transmission spectra of an electrochromic window based on polyaniline, tungsten oxide and a solid polymer electrolyte

Abstract An electrochromic window was fabricated by combining polyaniline and tungsten oxide with a solid polymer electrolyte binding the two electrochromic materials together. Polyaniline and tungsten oxide were deposited electrochemically on indium-tin-oxide glass plates. By applying a voltage between −1800 and +1600 mV, the transmission spectra for the electrochromic window show good light modulation in the 400–2700 nm wavelength region. For example, at 1000 nm the transmission changes from 0.76 to 0.22.Abstract An electrochromic window was fabricated by combining polyaniline and tungsten oxide with a solid polymer electrolyte binding the two electrochromic materials together. Polyaniline and tungsten oxide were deposited electrochemically on indium-tin-oxide glass plates. By applying a voltage between −1800 and +1600 mV, the transmission spectra for the electrochromic window show good light modulation in the 400–2700 nm wavelength region. For example, at 1000 nm the transmission changes from 0.76 to 0.22.

Synthesis of Hollow Silica Nanospheres by Sacrificial Polystyrene Templates for Thermal Insulation Applications

© 2013 Linn Ingunn C. Sandberg et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Electrochemical multilayer deposition of polyaniline and Prussian Blue and their application in solid state electrochromic windows

In an attempt to enhance the solar modulation in electrochromic windows, the electrochemical deposition of polyaniline (PANI) and Prussian Blue (PB) has been studied more closely. Several layers of PANI and PB at different thicknesses have been electrodeposited on top of each other, or intermixed in the coating matrices. This intermixing, or multilayer deposition, of PANI and PB may lead to an overall improved coating performance. Integrating over the whole solar spectrum, a modulation as high as 49% of the total solar energy has been achieved in solid state electrochromic windows based on tungsten oxide (WO3) and multilayer PANI–PB coatings, which is comparable to earlier results with a single PANI/PB layer.

Improving thermal insulation of timber frame walls by retrofitting with vacuum insulation panels – experimental and theoretical investigations:

Many of the Norwegian buildings from the 1960s–1980s with timber frame walls are ready for retrofitting. Retrofitting of these buildings with vacuum insulation panels (VIPs) may be performed without significant changes to the buildings, e.g., extension of the roof protruding and fitting of windows. Effectively, U-values low enough to fulfill passive house or zero energy requirements may be achieved; thus, contributing to a reduction of the energy use and CO2 emissions within the building sector. Retrofitting with VIPs on the exterior side is normally considered as a better solution; however, it may cause condensation in the wall. To investigate this and the interior option, four different wall fields were tested. One of them was a reference wall field built according to Norwegian building regulations from the 1970s, and three other fields represent different ways of increasing the thermal insulation level. In addition to the experiments, numerical simulations were performed where temperature, relative humidity, and surface wetness were measured. In total, the results from the experiments, simulations, and condensation controls conclude that timber frame buildings insulated with 100 mm mineral wool, might be retrofitted at the outside by adding 30 mm VIPs. However, this method for retrofitting provides limits to outdoor temperature, indoor moisture excess, and indoor temperature.

Dynamic light modulation in an electrochromic window consisting of polyaniline, tungsten oxide and a solid polymer electrolyte

Abstract The electrochemical and optical properties of an electrochromic window consisting of the two complementary electrochromic materials, polyaniline (PANI) and tungsten oxide (WO 3 ), have been investigated. Both PANI and WO 3 were electrochemically deposited on indium-tin oxide (ITO) glass substrates. Using the solid organic polymer electrolyte, poly(2-acrylamido-2-methyl-propane-sulfonic acid) (PAMPS), PANI and WO 3 were glued together. By applying a potential of ∼1.5V across the two external ITO contacts, we are able to modulate the light transmission, also in the near-infrared region (700–3000 nm), where about half of the solar energy lies, indicating that these ‘smart windows’ may significantly contribute to future energy savings in buildings. In order to study each of the electrochromic layers in the window, we have fabricated windows with holes in the electrochromic coatings, one window with a hole in the PANI film and another with a hole in WO 3 . This enables us to study the optical properties of PANI and WO 3 separately.