The advancement of smart metering and sensor technologies has opened the door to performing extensive in-situ measurements in buildings and a tendency to carry-out detailed energy and indoor climate monitoring, leading to the availability of the so-called “on-board monitoring data”. The data obtained through these measurements is of high value as it can be used for identification of parameters determining health, thermal comfort, and energy use. In this article, an occupied dwelling has been inspected and monitored for one year and the in-situ measurement and meteorological data are combined to feed a physic-based energy model. For the first time, the detailed data cleaning and filtering techniques are explained to give insight for future similar studies. The data is fed to a 1st – order circuit RC model, equivalent to the building's thermal model. Next, using Genetic Algorithm in a stated optimization problem, Inverse Modelling has been applied to identify four main global thermo-physical characteristics of the building, with a special attention to the heat loss coefficient. The results are compared by analysing three feed data properties: granularity level, period length, and time period, resulting the best fit in the coldest periods. The outcomes have shown the importance of these data properties by revealing differences in the heat loss coefficient in different periods and the weakening of the heat capacitance effect when feeding the model with low granularity level data. The daily values of the heat loss coefficient are then applied in combination with construction data to determine the daily averages of hourly air change rates. Finally, the method has been evaluated in terms of accuracy and precision and the air change rates have been validated using CO₂ concentration and wind velocity. Using this method, it is possible to determine buildings’ main global thermo-physical characteristics as well as the cold periods’ airborne heat losses.

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Accurate determination of building’s critical thermo-physical characteristics such as the walls’ thermal resistance, thermal conductivity, and volumetric heat capacity is essential to indicate effective and efficient energy conservation strategies at building level. In practice, the values of these parameters, which determine not only possible energy savings, but also related costs, are rarely available because the current determination methods are time-and-effort-expensive, and consequently seldom used. This thesis combines theories, simulations, computations, and experiments to develop and improve methods and approaches for determination of a number of buildings’ most important thermophysical characteristics. First, a modification to the existing standard method, “ISO 9869 Average Method” is proposed to measure the walls’ thermal resistance. Two current problems are solved: long measurement duration (weeks) and imprecision. To further shorten the measurement period to a few hours, a new transient in-situ method, Excitation Pulse Method, EPM (Patent No. 2014467), is then developed and tested. This method allows the determination of the walls’ response factors which can be applied directly in dynamic models. More importantly, it is used to extract critical construction information including walls’ thermal resistance, thermal conductivity, volumetric heat capacity, and the possible layer composition. Finally, in an attempt to reduce the hassle, cost, and intrusion associated with locally-conducted experiments, the use of data from smart meters and home automation systems is explored. Building’s global characteristics including heat loss coefficient, global heat capacitance and daily air change rates are accordingly determined.@en

Determination of the thermo-physical characteristics of the buildings' components is crucial to illustrate their thermal behavior and therefore their energy consumption. Along the same line, accurate determination of the thermal resistance of the building walls falls into one the most important targets. Following the difference between in-lab, and on site thermal performance of walls, in-situ measurements have been highly recommended. The most well-known practice for in-situ measurement of walls' thermal resistance is the Average Method of ISO 9869, using one heat flux meter and two thermocouples. The method, in comparison with other existing methods is quite straight-forward and therefore, is applied widely in large scale. Despite its simplicity, this method usually needs a relatively long time to reach an acceptable result. The current paper deals with a modification to the ISO 9869 method, making it in many situations much quicker than its original state. Through simulation of walls of different typologies, it is shown in which cases the measurement period becomes longer than expected. It is demonstrated how the addition of a heat flux meter to the aforementioned equipment can lead to a much quicker achievement of the thermal resistance, following the rest of the instructions of the standard method.

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Concerning the high levels of energy consumption in the existing building stock, the necessity for characterization of the building envelop is a well-known issue. Accordingly, numerous methods and practices have been developed and studied to measure the thermal resistance and other thermal characteristics of the walls in-situ. In the current paper, a previously proposed method, the Excitation Pulse Method, EPM, based on the theory of thermal response factors, is further studied and investigated through simulations, to rapidly measure the thermal resistance of existing walls. A prototype is built and introduced to carry out larger number of measurements on site. The triangular pulse's properties such as the relation between its magnitude and its time interval on its corresponding response are investigated. It is shown how changes in time interval can make the method sensitive to the number of residuals and affect its reliability. General constraints and validity domain of the method are studied. In addition, the effect of 3D heat transfer on the performance of the method is further illustrated in light and heavy constructions. It is shown in which cases it is possible to apply the method in-situ and measure the thermal resistance within a couple of hours.

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Accurate determination of walls' thermo-physical characteristics is a necessity for execution of energy conservation strategies in existing buildings. In practice, such data is not available because the current determination methods are time expensive and therefore rarely used. Based on the theory of Response Factors, a rapid transient in-situ method, Excitation Pulse Method, EPM, was introduced as proof of concept in a former article. In the present article, detailed conditions for accurate application of the method in heavy and multi-layered walls are further studied. Theory, simulations, and experiments are combined to determine the method's performance in different types of walls, with specific attention to the effects of the walls’ thermal response time and the response factors’ time interval, leading to the accuracy of R_c-value determination. It is demonstrated that the two main thermo-physical properties of a wall, thermal conductivity and volumetric heat capacity, as well as the wall's thickness can be determined using inverse modelling of the Response Factors. The ratios of the response factors have shown to determine wall's minimum thermal response time and to give an indication of the wall's composition. The use of longer time intervals has shown to be advantageous in terms of the accuracy and the performance of the method. Longer experiment times as a result of long time intervals are still considerably shorter than the time required for making measurements according to the current standards and other conventional methods.

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Accurate and reliable in-situ characterization of buildings’ thermal envelope is of high significance to determine actual energy use and thermal comfort. In this context, walls’ thermal resistance is one of the most critical properties to be identified. Regardless the numerous studies being carried out to accurately measure the actual thermal resistance of walls on site, the heat flow meter method suggested by the ISO 9869 standard is the one being applied the most. The method requires one heat flux sensor and two thermocouples to measure and estimate the average thermal resistance over a sufficiently long period. Despite the advantages of this method, two problems have been seen in practice: long duration and precision problem. The present article describes and demonstrates how modifications to this standard method can improve the results of the in-situ measurements in terms of duration and precision. Simulations and experiments have been applied to show the effect of using an additional heat flux sensor, opposite to the first one. The modified method aids in obtaining the thermal resistance with a higher precision in a shorter period of time.

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This report presents the results of the second part of the Monicair project1, which aim was to explore in how far the better determination of a number of parameters, which up to now were measured on-ly seldom, could support the development of better prediction models for the heating energy con-sumption in dwellings. Energy labelling calculations, as well as energy consumption forecasts, on which energy policies rely, are based on models. In the past years several studies have demonstrated that these models show large deviations from reality, making the prediction of possible energy sav-ings biased. These poor predictions can be hypothesised to be the result of poor estimation of the U–values of walls, poor estimation of the infiltration and ventilation flow rates and poor estimation of the heated surface area and of the temperature preferences of occupants. Additionally, there is very little knowledge on how occupant’s perception of comfort influences their ventilation and heating behaviour and finally the total energy use for heating. This report presents the results of a field study in which monitoring data was collected in order to further analyse parameters that could influence strongly the heating energy consumption and to fi-nally improve energy prediction models. A mix of modern and older dwellings was studied, as this can give a better idea of possible energy savings when renovating dwellings. @en

The in-situ estimation of the thermal resistance (Rc-value) of walls in buildings is of major significance to determine their energy performance. The exact construction of walls is generally unknown, especially in older buildings, making the estimation of the Rc-value inaccurate. In-situ measurement is generally not being performed because, for the current standard method (ISO 9869), generally a measurement period of more than ten days is required. In the present paper, a new transient in-situ measurement method (Excitation Pulse Method, EPM) based on the theory of response factors is derived, applied experimentally on three walls, showing that it is possible to measure the Rc-value within less than 2 h. The results are compared to the ones obtained by ISO 9869 method, showing a good agreement. Additionnally, EPM measurement technique can provide the average Volumetric Heat Capacity and thermal conductivity. It is also shown that the ISO 9869 method can be easily improved by using an additional heat flux meter. EPM is believed to make a significant contribution to the quick and accurate estimation of the thermal resistance in unknown constructions and therefore to the accuracy of the prediction of energy consumption in buildings.@en

Large deviations observed between the actual and theoretical gas consumption in Dutch dwellings, cast a shadow of doubt on the accuracy of the energy labeling method. In this sense, the accuracy of the calculation methods as well as the inputs being fed, fall under the question. According to several studies, the significance of wall’s thermal resistance as one of the most sensitive inputs has become clear. From the lack of sufficient information regarding the exact construction of the existing walls, arises a necessity for in-situ measurements. However, such measurements are generally not being performed because the existing methods demand very long monitoring periods. In this research, a rapid transient in-situ thermal resistance measurement technique, Excitation Pulse Method (EPM), has been introduced, experimentally applied to a case study, and compared to the existing international standard method ISO 9869, showing a very good agreement. EPM is based on the theory of thermal response factors. It allows in-situ determination of the walls’ thermal resistance and the average volumetric heating capacity in a couple of hours. The method is therefore believed to aid in better and much quicker estimation of the@en

Large deviations observed between actual and theoretical gas consumption in dwellings cast a shadow of doubt on the accuracy of the Energy Labeling method. Generally, such problem can stem from two different aspects: the calculation system and the inputs being fed. As one of the most critical parameters, the thermal transmittance U-value has been investigated from both perspectives.@en