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Measured vs translated irradiance on each glazed facade of the Holywell test house during the co-heating tests carried out there, an overshading factor of 0.77 has been applied to the translated irradiance.
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This thesis is concerned with measuring the fabric thermal performance of houses. This is important because the evidence shows that predictions of performance, based upon a summation of expected elemental performance, are prone to significant inaccuracy and in-situ performance is invariably worse than expected the so-called performance gap . Accura...
Citations
... with occupancy need non-intrusive instrumentation but can take place during a long period. Occupied methods mostly allow to determine an energy signature of a building (Fels 1986), but current studies are working on methodologies to estimate buildings heat losses (Bauwens, Ritosa, and Roels 2021;Jack 2019;Roels et al. 2015;Uriarte et al. 2020). Methods without occupancy are more developed and mostly consist of heating the inside of a building. ...
... Methods with occupancy need non-intrusive instrumentation but can take place during a long period. Occupied methods mostly allow to determine an energy signature of a building (Fels 1986), but current studies are working on methodologies to estimate buildings heat losses (Bauwens, Ritosa, and Roels 2021;Roels et al. 2015) (Jack 2019) (Uriarte et al. 2020). Methods without occupancy are more developed and mostly consist of heating the inside of a building. ...
Discrepancy between designed and as-built building performance can be quantified by a Heat Transfer Coefficient measurement. A reference method for measuring this coefficient is the co-heating test. However, the use of this method is limited to certain weather conditions. This work proposes a new method, complementary to the co-heating test, to be performed in summer or in hot climates, called the co-cooling test. This method consists in cooling the building instead of heating it. This article presents a numerical setup to prove the feasibility of the co-cooling test, determining ad-hoc linear regression models. To better account for solar gains, an equivalent outdoor temperature is used. In the cases studied, the simple linear regression method using an equivalent outdoor temperature enables the Heat Transfer Coefficient to be determined with errors below 10 %.
... Specifically, OBM can explain energy performance of a building as built, while theoretical estimation based on building physical parameters can contain disinformation about the current situation of a building. The HLC, which can be identified using OBM data, describes the insulation quality and airtightness of a building envelope in a single factor which makes it an understandable method in application and simultaneously highly explainable in the results [45]. HLC can be a noninvasive method that can be applied remotely. ...
The availability of building operational data such as energy use and indoor temperature provides opportunities to enhance the traditional building energy performance calculation. Disaggregated building energy use facilitates informed decision-making to identify cost-saving measures efficiently at the individual building and building stock levels. The existing energy performance analysis techniques with measured input data in the literature are fragmented. Moreover, they frequently approach this issue with varying degrees of complexity depending on the available input data, expertise, and time. The procedure of choosing an appropriate method is often cumbersome with limited indication of the usefulness of the outcomes. This study proposes a data-driven framework for end-use load disaggregation through techniques that exploit various kinds of building consumption data. The results demonstrate the use of different techniques for varied applications. Calibrated theoretical calculation, data-driven heat loss coefficient (HLC), and energy signature curve (ESC) are among the proposed methods in the framework that facilitate individual, and urban scale energy decomposition. It is observed that different methods yield unalike outcomes, while their performance is predictable. While the HLC methods are flexible but also highly sensitive to the input parameters, the ESC needs high-frequency time series but provides stable energy decomposition. The ESC is efficient for large-scale analysis and the HLC method for detailed case-specific applications. Calibrated theoretical energy decomposition has a simple workflow and can supplement the current energy performance assessment method, although it entails sufficient input data.
... The theoretical calculations of the in-situ performance which is the summation of the expected elemental performance can predict thermal buildings performance with a low accuracy worse than expected which is called the 'performance gap' [13]. In case of properties lack of the used insulation materials, theoretical methods will fail to predict the performance with any kind of accuracy. ...
... The test is considered to be invasive as the house should be vacant for 2 weeks during testing. In newly-built houses, a period of about one year as drying out period has to be fulfilled before carrying out the test [13]. ...
... A complete one year as drying out period has to be considered for new houses. For old houses, they should be vacant for 2 weeks during the test [13]. ...
Energy generation affects directly global warming. As buildings consume a large portion of the total generated energy, it is crucial to keep the energy consumption of this sector as less as possible. Poor insulation is the main source of energy losses from buildings envelopes. Although many countries have their rules now to control buildings insulation for new buildings, existing buildings still require a practical tool to check their insulation. In this work, a new approach named Building Insulation Analyzer is developed and coded (BIA Software) to measure the differences between the inside and the outside temperatures at each point from the building façade. It has been found that three points using the first degree polynomial equation are optimum for the registration. A stable behavior is shown in the validation process. The temperature differences for the studied façade were ranged from two degrees at the openings to five degrees at the isolated and thick walls.
... The result follows previous results (i.e., thermal resistance), indicating the necessity of increasing the adjusted thermal resistance for the roof and floor in contact with the exterior at least equal to the normed value. Simultaneously, the results are consistent with the findings from the literature [49,50], mentioning that residential buildings' performance can be highly variable, and even similar houses could have dramatically different performance levels. Nevertheless, as it was mentioned in Reference [22], the building's envelope plays a pivotal role in reducing the energy demand for heating or cooling. ...
The building sector continues to play an essential role in reducing worldwide energy consumption. The reduced consumption is accompanied by stricter regulation for the thermotechnical design of the building envelope. The redefined nearly Zero Energy Building levels that will come into force for each member state will pressure designers to rethink the constructive details so that mandatory levels can be reached, without increasing the construction costs over an optimum level but at the same time reducing greenhouse gas emissions. The paper aims to illustrate the main conclusions obtained in assessing the thermo-energy performance of a steel-framed building representing a holistically designed modular laboratory located in a moderate continental temperate climate, characteristic of the south-eastern part of the Pannonian Depression with some sub-Mediterranean influences. An extensive numerical simulation of the main junctions was performed. The thermal performance was established in terms of the main parameters, the adjusted thermal resistances and global thermal insulation coefficient. Further on, the energy consumption for heating was established, and the associated energy rating was in compliance with the Romanian regulations. A parametric study was done to illustrate the energy performance of the investigated case in the five representative climatic zones from Romania. An important conclusion of the research indicates that an emphasis must be placed on the thermotechnical design of Light Steel Framed solutions against increased thermal bridge areas caused by the steel’s high thermal conductivity for all building components to reach nZEB levels. Nevertheless, the results indicate an exemplary behaviour compared to classical solutions, but at the same time, the need for an iterative redesign so that all thermo-energy performance indicators are achieved.
... The spread of results was principally due to the different methods of analysis, as opposed to significant variations in the way that the different participants set up and conducted the test (Butler & Dengel, 2013). Jack (2015) subsequently reviewed the sensitivity of analysis and reproducibility of the method using data from the same study and found that when the precise data collection and methods are followed the HTC can be reported with an uncertainty of ±10%. Thus, within the work reported here, further consideration is given to the analysis and uncertainty of the results. ...
This report details work carried out by the Technical Assessment Contractor for the Department of Business Energy and Industrial Strategy (BEIS) during Phase 2 of the Technical Evaluation of SMETER technologies (TEST) Project under the Smart Meter Enabled Thermal Efficiency Ratings (SMETER) Innovation Programme. The Technical Assessment Contractor, referred to here as the TEST team, comprises experts from Loughborough University, Leeds Beckett University, UCL, and Halton Housing.
... The main principle from the early coheating tests continued to be used to estimate the thermal characteristics of the building envelope, notwithstanding that the methods to heat the building are now undertaken with independent electrical heaters, which are more easily metered and measured. The principle of obtaining a HTC through the electric coheating test has been applied extensively to evaluate the fabric building performance (Bauwens and Roels, 2014;Bell and Lowe, 1998;Francisco et al., 2006;Glew, 2021;Jack, 2015;Jack et al., 2018;Lowe et al., 2007;Palmer and Pane, 2011;Roels et al., 2017;Stamp et al., 2017;Stamp, 2016) With questions over the accuracy of coheating being raised an evaluation of coheating was undertaken by the NHBC in the UK through a series of tests by different groups on the same building (Butler and Dengel, 2013). The tests, which were undertaken between December and May 2011 reported a maximum uncertainty in the HTC of 17%. ...
... The significant difference between the two methods is that the building can be occupied and heated to "normal" levels rather than overheating. The building can be occupied for the duration of the test (Jack, 2015). ...
Assembling the knowledge, tools, and skills to reliably determine the (Heat Transfer Coefficient) HTC of a dwelling was a main driver for Annex 71. However, research has been carried out in this area for several years. What has set this work apart was the idea of measurement of the HTC using cost effective data, such as smart meters and on-board devices such as thermostats, using complex analyses.
The purpose of this report was to look at what goes into these analyses and what comes out. We carried out work thus on the data inputs and data outputs.
An introduction to the HTC was presented with its simple uses and benefits presented.
A review of the industry views and opinions across the member countries of this Annex. From here we assembled a large piece of research around the current methods used to do this work (the established and more modern ways of measuring the HTC).
We examined the current data inputs available in this area, such as smart controls and a complete review of smart meter data across the EU. This included a state-of-the-art review of Building Automation Solutions (BAS).
A series of use cases are presented with several international case studies, alongside some suggested future use cases for the metric.
https://bwk.kuleuven.be/bwf/projects/annex71/data/EBC_Annex71-ST1-4-Challenges_and_general_framework.pdf
ISBN 9789075741001
... This was carried out in three homes under simulated occupancy and normal occupancy conditions, and the accuracy was found to be around ±15% when compared to a Co-heating baseline. CAM(B)BRIDGE (acronym for Calculation and Measurements in Buildings: Bridging the Gap) is a methodology based on experiments presented by Masy et al. and aimed at measuring the HTC of a building façade in collective buildings where the testing of a unit has to be done without accessing the adjoining zones [31]. The measurement process was originally intended to be carried out in 9 days, but experiments showed that a 4 day period is sufficient when the measurement is performed during summer in units that are sun exposed and benefit from significant solar heat gains. ...
The heat transfer coefficient (HTC) is a very important factor influencing the energy performance of a building. Recent studies have shown the importance of on-site measurements of the HTC in reducing the performance gap in buildings. However, its measurement setup and calculation procedures are known to be intense and complex. Due to this, many stakeholders in the building industry find it impractical and insufficient for their needs. This paper presents the results of an international survey that targets such stakeholders with the aim to get their perspectives on HTC measurements on-site. Several stakeholders from 14 countries in Europe participated in the survey. The survey is categorized into four parts: a) basic data about the participants, b) their interest in methods for measured energy performance, c) their views on the characteristics of such a methodology and d) their concerns and opportunities. The results reveal that the stakeholders are highly interested in measuring the HTC on-site. The results also provide interesting insights on the aspects relevant for them and their customers. In particular, we elaborate on their perspective on the time to conduct the measurement, the cost of the setup, the measurement duration and the acceptable error. The assimilated understanding from the survey will help the building and the construction industry to identify opportunities for a progressive assessment campaign involving on-site measurements. This study is part of the International Energy Agency's Energy in Buildings and Communities Programme (IEA EBC) Annex-71 project titled ‘Building energy performance assessment based on optimized in-situ measurements’.
... The result follows previous results (i.e., thermal resistance), indicating the necessity of increasing the adjusted thermal resistance for the roof and floor in contact with the exterior at least equal to the normed value. Simultaneously, the results are consistent with the findings from the literature [49,50], mentioning that residential buildings' performance can be highly variable, and even similar houses could have dramatically different performance levels. Nevertheless, as it was mentioned in Reference [22], the building's envelope plays a pivotal role in reducing the energy demand for heating or cooling. ...
This Special Issue is dedicated to the analysis of recent
advances on: 1, thermal performance of building’s elements; 2,
energy efficiency in buildings; 3, sustainable construction. All
types of research approaches are acceptable: experimental,
theoretical, numerical, analytical, computational, case
studies, and combinations thereof. The main criteria
for paper acceptance is the academic excellence, the
scientific soundness, as well as the originality and novelty of
applications, methods, fundamental findings or experiments.
The Special Issue will include the following topics: Thermal
improvement of building’s components; Thermal bridges
assessment and mitigation; Energy efficiency in buildings;
Thermal inertia increase techniques; Building location
and climate: air temperature, solar radiation, relative
humidity, wind speed and direction, ground temperature,
daylight hours, etc; Building envelope: air tightness,
thermal insulation, glazed openings, shading, etc; Building
services: appliances, illumination, heating, air-conditioning,
ventilation, heat recover, hot water production, etc; Human
factors: occupancy schedule, utilization type, internal
heat gains, etc; Passive heating and cooling techniques:
natural ventilation, solar heat gains, Trombe walls, ground
source heat exchangers, etc; Renewable energy sources for
building applications: solar collectors for domestic hot water
production, photovoltaic solar panels, wind turbines, etc;
Optimization of thermal behaviour and energy efficiency of
buildings; Environmental life cycle assessment of buildings
and building components; Life cycle cost assessment of
buildings and building components; Building’s operational
and embodied energy.
... Stamp [10] also discussed the uncertainty introduced to coheating tests from the ground floor losses. Research on the thermal performance of uninsulated concrete floors has showed the spatial variation on the heat losses closer to the perimeter (e.g., see [31][32][33]) while Jack [34] recommended quantifying the ground floor losses as a topic of future research to advance knowledge on the uncertainty in coheating tests. ...
In this paper the findings from a long-term field study of the thermal performance of a circa 1950s dwelling are presented and discussed. The study aimed at evaluating the robustness of the QUB method in the field under UK climatic conditions. A series of 147 QUB tests were performed during the whole heating period (September 2016 – March 2017) in a detached house located in the University Park campus, University of Nottingham considering two distinct conditions: as-built and with increased airtightness.
The QUB method was able to provide consistent and robust estimates of the Heat Transfer Coefficient (HTC) of the whole dwelling with approximately 80% of the results within
±10% from the mean and more than 95% of the results within ±15%. The need to treat heat losses occurring through the ground when assessing the thermal performance of buildings through experimental diagnostics methods was highlighted, especially in uninsulated concrete slab floors. The method devised to isolate the ground floor heat losses from the whole building losses resulted in reduced dispersion of the adjusted Heat Transfer Coefficient with a coefficient of variation of 5% and 98% of results within ±10% from the mean.
