•Determination of thermal properties of PCM concrete composite•New experimental method to define latent heat storage in inhomogeneous composite.•Passive potential for heat storage in the concrete deck with microencapsulated PCM.The study presented in this paper focuses on an experimental investigation of the specific heat capacity as a function of the temperature Cp (T) of concrete mixed with various amounts of phase change material (PCM). The tested specimens are prepared by directly mixing concrete and microencapsulated PCM. This paper describes the development of the new material and the experimental set-up to determine the specific heat capacity of the PCM concrete material. Moreover, various methods are proposed and compared to calculate the specific heat capacity of the PCM concrete. Finally, it is hoped that this work can be used as an inspiration and guidance to perform measurements on the various composite materials containing PCM.

The emission rate is considered to be a good indicator of the emission characteristics of formaldehyde and volatile organic compounds (VOCs) from building materials. In contrast to the traditional approach that focused on an experimental study, this paper uses a theoretical approach to derive a new correlation to characterize the relationship between the emission rate and temperature for formaldehyde emission. This correlation shows that the logarithm of the emission rate by a power of 0.25 of the temperature is linearly related to the reciprocal of the temperature. Experimental data from the literature were used to validate the derived correlation. The good agreement between the correlation and experimental results demonstrates its reliability and effectiveness. Using the derived correlation, the emission rate at temperatures other than the test condition can be obtained, greatly facilitating engineering applications. Further analysis indicates that the temperature-related emission rate of other scenarios, i.e., the standard emission reference and semi-volatile organic compounds (SVOCs), also conforms to the same correlation as that of formaldehyde. The molecular dynamics theory is introduced to preliminarily understand this phenomenon. Our new correlation should prove useful for estimating the emission characteristics of chemicals from materials that are subject to changes in temperature.

This paper puts forward an approach to determine the optimal mode of doping adsorbents into the wood-based panels for control of their formaldehyde emission. Based on the optimization conclusion, a novel design method for low-emitting wood-based panels by daubing adsorbent layer on the panel’s surface is proposed. The formaldehyde emission results from the prepared laboratory specimens indicate the feasibility of the proposed method. This study provides a meaningful guidance on designing low-emitting wood-based panels.

The initial emittable formaldehyde and VOC concentration in building materials (C0) is a key parameter for characterizing and classifying these materials. Various methods have been developed to measure this parameter, but these generally require a long test time. In this paper we develop a convenient and rapid method, the variable volume loading (VVL) method, to simultaneously measure C0 and the material/air partition coefficient (K). This method has the following features: (a) it requires a relatively short experimental time (less than 24 h for the cases studied); and (b) is convenient for routine measurement. Using this method, we determined C0 and K of formaldehyde, propanal and hexanal in one kind of medium density fiberboard, and repeated experiments were performed to reduce measurement error. In addition, an extended-C-history method is proposed to determine the diffusion coefficient and the convective mass transfer coefficient. The VVL method is validated by comparing model predicted results based on the determined parameters with experimental data. The determined C0 of formaldehyde obtained via this method is less than 10% of the total concentration using the perforator method recommended by the Chinese National Standard, suggesting that the total concentration may not be appropriate to predict emission characteristics, nor for material classification.

The initial emittable concentration (Cm,0), the diffusion coefficient (Dm), and the material/air partition coefficient (K) are the three characteristic parameters influencing emissions of formaldehyde and volatile organic compounds (VOCs) from building materials or furniture. It is necessary to determine these parameters to understand emission characteristics and how to control them. In this paper we develop a new method, the C-history method for a closed chamber, to measure these three parameters. Compared to the available methods of determining the three parameters described in the literature, our approach has the following salient features: (1) the three parameters can be simultaneously obtained; (2) it is time-saving, generally taking less than 3 days for the cases studied (the available methods tend to need 7−28 days); (3) the maximum relative standard deviations of the measured Cm,0, Dm and K are 8.5%, 7.7%, and 9.8%, respectively, which are acceptable for engineering applications. The new method was validated by using the characteristic parameters determined in the closed chamber experiment to predict the observed emissions in a ventilated full scale chamber experiment, proving that the approach is reliable and convincing. Our new C-history method should prove useful for rapidly determining the parameters required to predict formaldehyde and VOC emissions from building materials as well as for furniture labeling.

Epidemiological and toxicological studies have proved that semi-volatile organic compounds (SVOCs) may have significant adverse effects on human health. For example, phthalic acid esters (PAEs), polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) may harm the endocrine, reproductive and respiratory systems of humans. Moreover, some SVOCs are carcinogenic. This paper summarizes the source emission characteristics for typical SVOCs observed indoors, evaluates the gas-phase and particle-phase concentrations of indoor di-2-ethylhexyl phthalate (DEHP) under the steady-state condition, estimates the exposure of PAEs and the health risk of PAHs, and then proposes some solutions to some urgent problems for indoor SVOC pollution. The results show that the production and consumption quantities of plasticizers, coal and cigarettes in China are the highest in the world, and that the consumption of flame retardants and pesticides are also very high. As estimated, indoor plasticizer and flame retardant concentrations are higher in China than that of the developed countries such as the USA, which implies that indoor SVOC pollution may be more serious in China. According to the model analysis, DEHP remains mainly in the particle-phase under the steady-state condition; the particle-phase concentration of DEHP increases with increasing particle concentration. The exposure of DEHP is higher for children than it is for adults. It is estimated that 260 thousand people are diagnosed with cancer resulting from exposure to PAHs every year. A multidisciplinary approach to the further study of indoor SVOC pollution is necessary.

Improving the thermal performance of building envelope is an important way to save building energy consumption. The phase change energy storage building envelope is helpful to effective use of renewable energy, reducing building operational energy consumption, increasing building thermal comfort, and reducing environment pollution and greenhouse gas emission. This paper presents the concept of ideal energy-saving building envelope, which is used to guide the building envelope material selection and thermal performance design. This paper reviews some available researches on phase change building material and phase change energy storage building envelope. At last, this paper presents some current problems needed further research.

Thermal performance of two phase change material (PCM) composites, mixed type PCM-gypsum and shape-stabilized PCM plates, has been numerically evaluated in a passive solar building in Beijing with an enthalpy model. Effects of the melting temperature and phase transition zone of the PCM are analyzed and a comparison between the two types of PCM composites is performed. The results show that: (1) for the present conditions, the optimal melting temperature is about 21 °C; (2) PCM composites with a narrow phase transition zone provide better thermal performance; (3) both mixed type PCM-gypsum and shape-stabilized PCM plates effectively shave the indoor temperature swing by 46% and 56%, respectively; (4) the shape-stabilized phase change material (SSPCM) plates respond more rapidly than the mixed type PCM-gypsum and prove to be thermally more effective in terms of utilizing the latent heat.

Relative humidity (RH) is one of the main environmental factors affecting the emission behaviours of formaldehyde from building materials. Meanwhile, the initial emittable concentration (Cm,0) is proved to be the most sensitive key parameter to the emission behaviours. However, there is no report on the relationship between RH and Cm,0. In this paper, Cm,0 of formaldehyde from a type of medium density fiberboard in RH range of 20%-85% were tested by the ventilated C-history method. Experimental results show that Cm,0 increased by 10 times when RH rising from 20% to 85%. A linear relationship between ln(Cm,0) and RH is obtained based on the experimental results. A correlation characterizing the association of emission rate and RH is also derived. With the correlations, the Cm,0 or emission rate different from test RH conditions can be conveniently obtained. This study should be useful for predicting the emission characteristics under varied RH conditions.

For the materials with constant thermophysical properties, the thermal performance of wallboards (or floor, ceiling) can be described by decrement factor f and time lag φ. However, the phase change material (PCM) may charge large heat during the melting process and discharge large heat during the freezing process, which takes place at some certain temperature or a narrow temperature range. The behavior deviates a lot from the material with constant thermal physical properties. Therefore, it is not reasonable to analyze the thermal performance of PCM wallboard by using the decrement factor f and time lag φ. How to simply and effectively analyze the thermal performance of a PCM wallboard is an important problem. In order to analyze and evaluate the energy-efficient effects of the PCM wallboard and floor, two new parameters, i.e., modifying factor of the inner surface heat flux ‘α’ and ratio of the thermal storage ‘b’, are put forward. They can describe the thermal performance of PCM external and internal walls, respectively. The analysis and simulation methods are both applied to investigate the effects of different PCM thermophysical properties (heat of fusion Hm, melting temperature Tm and thermal conductivity k) on the thermal performance of PCM wallboard for the residential buildings. The results show that the PCM external wall can save more energy by increasing Hm, decreasing k and selecting proper Tm (α < 1); that the PCM internal wall can save more energy by increasing Hm and selecting appropriate Tm, k. The most energy-efficient approach of applying PCM in a solar house is to apply it in its internal wall.