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The current decarbonization transition to be achieved by 2050 according to the European Council has given great prominence to the use of Digital Twins as tools for energy management. For their correct operation, it is essential to control the uncertainties of the energy models, which lead to differences between the measured and predicted data. One of the key parameters that is most difficult to assess numerically is air leakage. The existent infiltration models available in EnergyPlus were developed to be applied in low-rise residential buildings with fewer than three stories. Therefore, it is common to rely on air leakage equations employing predefined coefficients. This research presents an empirical assessment of the performance of two EnergyPlus air leakage models, the "Effective Leakage Area" and the "Flow Coefficient", in predicting dynamic infiltration within the attic of a seven-story building. Blower door tests, along with the application of CO2 tracer gas, were conducted to establish coefficients for the models. Then, they were evaluated in three independent periods according to the criteria established in the American Society for Testing Material D5157 Standard. Those models that only used in situ coefficients consistently met the standard across all three periods, demonstrating for both equations their accurate performance and reliability. For the best model derived from tracer gas data, the R2 and NMSE values are 0.94 and 0.019, respectively. In contrast, the model developed using blower door test data and EnergyPlus default values presented a 64% reduction in accuracy compared to the best one. This discrepancy could potentially lead to misleading energy estimates. Although other software options exist for estimating infiltration, this study specifically targets EnergyPlus users. Therefore, these findings offer valuable insights to make more informed decisions when implementing the infiltration models into energy simulations for high-rise buildings using EnergyPlus. [ABSTRACT FROM AUTHOR]

The airtightness of a building has a significant impact on energy savings, structural longevity, and indoor air quality for occupants. Therefore, it is essential to accurately measure the airtightness of buildings, though the widely used fan pressurization method suffers from several shortcomings. For this reason, transient methods have recently emerged to assess airtightness by monitoring pressure changes over time, but studies using transient methods in this field are rare. In this study, we selected three representative buildings to conduct field tests to verify the practical applicability of the improved transient method. To verify the results of the transient method, we conducted a comparison experiment with the blower door test: a widely used measurement method. When measuring the effective leakage area, the average standard deviation of the transient method was 0.903 cm2, which was much smaller than the blower door test result of 1.488 cm2. In addition, the recorded standard errors ranged from 0.197 cm2 to 0.816 cm2 for the transient method and from 0.269 cm2 to 1.801 cm2 for the blower door test. Notably, the transitional method was more reproducible than the blower door test while showing similar accuracy. Given these results, it is expected that the improved transitional method can be used to evaluate airtightness performance in the field. [ABSTRACT FROM AUTHOR]

The thermal performance of building envelopes is significantly affected by building insulation and airtightness. However, most studies have focused on improving thermal performance in building envelopes, while few studies on improving airtightness in buildings have been conducted. The present study measured airtightness and infiltration in non-residential buildings using fan pressurization and tracer gas methods. By analyzing the results obtained from both methods, the distribution of the correlation factors was identified, which can be used for the air leakage rates obtained from the blower door test to estimate the infiltration rates under natural airflow conditions. Since it is difficult to get the values of ACH50 through the blower door test in buildings of large volume or where large air leakages occur, the study proposed a method to convert the values of airtightness under several low-pressure differences of 20 Pa, 25 Pa, 30 Pa and 35 Pa into ACH50 using conversion coefficient. By dividing the air leakage rate under 20 Pa pressure difference by the conversion coefficient of 0.60, the values of ACH50 can be estimated. Results converted to ACH50 using conversion coefficient for various pressure differences of 20 Pa, 25 Pa, 30 Pa, and 35 Pa showed an error of 0.1–4.4%, respectively, compared to actual ACH50 measurement results. [ABSTRACT FROM AUTHOR]

Airtightness impact on the heating and cooling demand of new single‐family houses The airtightness of buildings has an influence on the ventilation heat flow and thus on the heating and cooling demand. The uncontrolled air flow through leakages becomes more important with increasing insulation levels. Based on coupled thermal and air flow simulations, the influence of airtightness with a high insulation standard on the heating and cooling demand is investigated for different scenarios. In addition, airtightness measurements are carried out for 28 new single‐family houses to determine the airtightness of standard new buildings. The simulations confirm that the heating and cooling demand increases with decreasing airtightness. As a result of the large temperature difference between inside and outside and higher wind speeds in winter, the influence of airtightness on the heating demand is greater than on the cooling demand in summer. The average airtightness of the measured buildings is found to be q50 = 0.8 m3/(h · m2), which is a very good airtightness value. Their heating demand will probably increase by approx. 3–6 % due to the air leakage compared to a tight building of q50 = 0.6 m3/(h · m2). The cooling demand on the other hand will decrease by approx. 1–2 %. [ABSTRACT FROM AUTHOR]

One of the important factors influencing the thermal performance of buildings is the leakage of the envelope. When it comes to Montenegro, although there is a formal airtightness requirement, air permeability tests are not mandatory and therefore there is a lack of data in this regard. This paper reports the results of fan pressurization tests on a single apartment in a multi-family residential building before and after replacing the windows. The replacement of old wooden windows with new UPVC ones, provided that the installation is carefully supervised, proved to be an effective air tightening measure, as it resulted in a reduction of air change rate at the reference building pressure from 6.25 h−1 to 0.77 h−1, or by nearly 90%. The energy impact of air leakage was evaluated using the national software for calculating the energy performance of buildings based on the DIN V 18599 methodology. Calculations showed that by reducing infiltration, significant energy savings for heating can be achieved, while savings for cooling are practically negligible. Savings in relative terms were greater when the façade walls were thermally insulated and when the building was located in a colder climate zone. Savings in delivered energy ranged from 13 to 25 kWh/m2·year, depending on the climate zone. [ABSTRACT FROM AUTHOR]

The current decarbonization transition to be achieved by 2050 according to the European Council has given great prominence to the use of Digital Twins as tools for energy management. For their correct operation, it is essential to control the uncertainties of the energy models, which lead to differences between the measured and predicted data. One of the key parameters that is most difficult to assess numerically is air leakage. The existent infiltration models available in EnergyPlus were developed to be applied in low-rise residential buildings with fewer than three stories. Therefore, it is common to rely on air leakage equations employing predefined coefficients. This research presents an empirical assessment of the performance of two EnergyPlus air leakage models, the “Effective Leakage Area” and the “Flow Coefficient”, in predicting dynamic infiltration within the attic of a seven-story building. Blower door tests, along with the application of CO2 tracer gas, were conducted to establish coefficients for the models. Then, they were evaluated in three independent periods according to the criteria established in the American Society for Testing Material D5157 Standard. Those models that only used in situ coefficients consistently met the standard across all three periods, demonstrating for both equations their accurate performance and reliability. For the best model derived from tracer gas data, the R2 and NMSE values are 0.94 and 0.019, respectively. In contrast, the model developed using blower door test data and EnergyPlus default values presented a 64% reduction in accuracy compared to the best one. This discrepancy could potentially lead to misleading energy estimates. Although other software options exist for estimating infiltration, this study specifically targets EnergyPlus users. Therefore, these findings offer valuable insights to make more informed decisions when implementing the infiltration models into energy simulations for high-rise buildings using EnergyPlus.

If infiltration is uncontrolled and admits unconditioned air, the results will be undesirable. Controlling this problem will increase thermal comfort and decrease energy consumption. The aim of this paper is to assess the performance of different materials used to improve airtightness, which will increase energy efficiency. This research primarily adopted an experimental approach. A typical residential building in UAE was chosen as a case study. Current airtightness status was measured using a blower door test and infrared technique. Six commonly used materials used for airtightness in UAE were identified and applied in different zones of the building envelope, including exterior walls, door and windows. The test was run before implementing airtightness strategies, following which they were applied for one year. Overall performance and energy reduction were monitored to identify how consumption fell by which method was the most efficient. The results indicate that energy was 3% when applying the 6 different airtightness strategies. The base case energy consumption was 64,287 kWh per year. The energy consumption then decreased after applying the sealants to 62,341 kWh per year. Future recommendations are made to enhance airtightness in residential buildings in a hot and arid climate. [ABSTRACT FROM AUTHOR]

The European Union has adopted legislation aimed to increase the use of renewable energy and improve the effectiveness of conventional-form energy use. Additional structure insulation helps to decrease heat energy loss. Airtightness of the building envelope (building airtightness) is an additional factor that determines comfortable and energy-saving living environment. The conformity of heat energy loss with the object’s design energy class is one of the mandatory indicators used in the obligatory building energy performance certification procedure. Optionally, the objects to be certified are the entire buildings or separate units (flats). There is an issue of concern whether a flat assessed as a separate housing unit would meet the requirements of design energy class depending on the location of the unit in the building. The study is aimed to determine the change in heat loss of end units in terraced houses (townhouses) as a result of various factors, leading to uneven airtightness of the building envelope. The non-destructive assessment of building airtightness was implemented through the combined use of methods, namely Blower Door Test (around 200 measurements) and Infrared Thermography. The hollow clay unit masonry showed ca. 7–11% less airtightness than the sand–lime block masonry structure. The end units were up to 20% less airtight compared to the inside units.

A pulse pressurisation technique is developed and utilised for determining building leakage at low pressure, based on a “quasi-steady pulse” concept. The underlying principle of the technique is to subject the building envelope to a known volume change in a short period of time (typically 1.5 s). The resulting pressure pulse is recorded, from which the leakage characteristic at low pressure is determined. The technique minimizes the effects of wind and buoyancy forces and has proven to be repeatable. It can use a compact and portable test rig and does not need to penetrate the building envelope. Therefore, it can obtain the leakage of a building very quickly and efficiently. Throughout the various stages of research and development of the pulse technique, experimental investigations have been carried out under different configurations and scenarios in order to validate the changes that have been made for the purpose of system development and optimisation. This paper provides an overview of experimental investigations in the validation process by covering comparison between blower door and pulse unit, comparison between piston-based pulse unit and nozzle-based pulse unit, testing with multiple pulse units in a large building, testing with a known opening, and testing in different building types with a range of volumes and airtightness levels. It enables us to understand the strengths and the limits of the pulse technique, from the experimental and practical perspectives. A good repeatability level (within ±5%) has been maintained throughout the various developmental stages and the average value of Q50/Q4 reported herein was in close agreement (

The airtightness of eight apartment buildings containing six to 11 units each on three or four floors was tested with and without guard-zone pressure, that is, with and without consideration of internal leakages. The layouts of these buildings varied: two of them had no central stairwell; in two other buildings, only some of the apartments were connected to the central stairwell; and the third type had all apartments connected to a central stairwell. Airtightness tests were performed with and without guard-zone pressure conditions. During these tests, two to eight BlowerDoor systems were used simultaneously to create guard-zone pressure conditions. In this report, the authors evaluate the test results of three buildings of different layout types. Furthermore, a reference model for the natural air permeability of all construction materials used in the interior and exterior envelopes of each apartment was created for two buildings in accordance with the German Industrial Standards (DIN). We present the results of this assessment and put them in context with the airtightness tests with and without guard-zone pressure. The results indicate that the air leakage contribution of internal partitions is significant, namely 32% and 27%. As this affects sound transmission, fire protection, odor transfer, and the quality of ventilation, it is essential to assess the airtightness of not only the exterior but also the interior envelope of each apartment. [ABSTRACT FROM AUTHOR]

Ingress of air from neighboring apartments is an important source of fine particulate matter (PM2.5) in residential multi-story buildings. It affects the measurement and estimation of particle deposition rate and penetration factor. A blower-door method to measure the particle deposition rate and penetration factor has previously been found to be more precise than the traditional decay-rebound method as it reduces variability of PM2.5 ingress from outside. CONTAM is a multi-zone indoor air quality and ventilation analysis computer program to aid the prediction of indoor air quality. It was used in this study to model the indoor PM2.5 concentrations in an apartment under varying PM2.5 emission from neighboring apartments and window opening and closing regimes. The variation of indoor PM2.5 concentration was also modeled for different days to account for typical outdoor variations. The calibrated CONTAM model aimed to simulate environments found during measurement of particle penetration factor, thus identifying the source of error in the estimates. Results show that during simulated measurement of particle penetration factors using the blower-door method for three-hour periods under a constant 4 Pa pressure difference, the indoor PM2.5 concentration increases significantly due to PM2.5 generated from adjacent apartments, having the potential to cause an error of more than 20% in the estimated value of particle penetration factor. The error tends to be lower if the measuring time is extended. Simulated measurement of the decay-rebound method showed that more PM2.5 can penetrate inside if the PM2.5 was generated from apartments below under naturally variable weather conditions. A multiple blower-door fan can be used to reduce the effects of neighboring emission and increase the precision of the penetration estimates.

Abstract A detailed study of a large national airtightness database was undertaken. Univariate analyses and multiple linear regression based on air change rate and normalised leakage was performed. Univariate analyses revealed important regional and national airtightness trends. Equations predicting pressurised air leakage were developed based on Canadian homes at the pre-retrofit stage. This data set contained homes in 11 of 13 of provinces/territories throughout Canada. Air leakage was examined by building jurisdiction, overall building height, building volume, build date, heating degree days, and enclosure insulation levels. Pearsons correlation coefficient for 3-variable models were moderate in strength explaining 32%–35% of the variability in both the ACH and NL based air leakage metrics respectively. Improvement in model strength was demonstrated using a 330,000 home dataset in conjunction with an 8-variable model. The 8-variable model raised the explanatory power between 46% and 48% for the ACH and NL metrics respectively. The study established a potential lower bound for future regression based airtightness prediction models across Canadian households. [ABSTRACT FROM AUTHOR]

The European Council has proposed reducing buildings' energy consumption as one way to decarbonization by 2050. Currently, digital twins are used for real-time energy management, but there are discrepancies between predicted and measured energy performance due to uncertainties in building energy models (BEMs). Air leakage is a key parameter that is difficult to obtain and EnergyPlus users often employ a constant value or apply air leakage equations with pre-determined coefficients. This research is a preliminary step in reducing this uncertainty in the author's methodology of BEMs calibration, using EnergyPlus and measured data. The study empirically verifies the ability of the EnergyPlus model's design flow rate to accurately replicate dynamic infiltration values within a zone of a high-rise residential building, where a tracer gas test using CO 2 and a blower door test were conducted. Three new methods for calculating I d e s i g n were developed and evaluated. The results were assessed based on the American Society for Testing Material D5157 (Standard Guide for Statistical Evaluation of Indoor Air Quality Models). The models generated with ad-hoc coefficients were compared to those from the literature (EnergyPlus, DOE-2, and BLAST). Among the models with off-the-shelf coefficients, the one with I d e s i g n calculated with in situ data and DOE-2 coefficients demonstrates an accuracy that is only 26% lower than the best model with regression coefficients, which has an R2 value of 0.94 and an NMSE value of 0.02 in the training period. [ABSTRACT FROM AUTHOR]

In order to fulfil the European Energy Performance of Buildings Directive (EPBD) requirements for the reduction of energy consumption, European national requirements have been created for building envelope thermal properties and calculation methodology to determine if building energy efficiency is created. This is however not true in all methodologies. The necessity of building air tightness appears only for new A class buildings, and there are no requirements for air tightness for other building classes. Therefore, the aim of this work is to improve the methodology for the calculation of energy efficiency of buildings, while taking into account the air tightness of the buildings. In order to achieve this aim, the sum energy consumption of investigated buildings was calculated, energy efficiency classes were determined, air tightness of the buildings was measured, and reasons for insufficient air tightness were analyzed. Investigation results show that the average value of air tightness of A energy efficiency class buildings is 0.6 h−1. The results of other investigated buildings, corresponding to B and C energy efficiency classes, show insufficient air tightness (the average n50 value is 6 h−1); herewith, energy consumption for heating is higher than calculated, according to the energy efficiency methodology. This paper provides an energy performance evaluation scheme, under which performed evaluation of energy performance of buildings ensures high quality construction work, building durability, and the reliability of heat-loss calculations.

Abstract: Air tightness (or permeability) is a property of a building envelope that describes how air moves though it when subjected to a pressure difference (wind, stack effect, etc.), this impacts on building performance including energy usage, thermal comfort and air quality. The NSW Land and Housing Corporation (LAHC) implemented a pilot program of simple leak (or draught) sealing measures to improve air permeability and building performance on some of its domestic building stock. The effectiveness of this program was evaluated via blower door testing to international standards including measuring overall envelope permeability, and qualitative and quantitative investigation of the leakage paths through the structure. Testing was undertaken before and after the leak sealing interventions to determine the relative impact, the extent of the works implemented was documented, and potential for further improvements investigated. [ABSTRACT FROM AUTHOR]

There is little known on the airtightness performance of residential buildings in China. The present study intends to investigate the airtightness performance of ten detached houses in China's cold area using “blower door test”. The thermal infrared imager and smoke pencil were used to find out the typical air leakage places in the building envelope. Test results show that the air change rate at the pressure difference of 50 Pa of the tested houses varies from 1.89 h −1 to 0.84 h −1 with a mean value of 1.42 h −1 . The typical air leakage places happen at the reserved holes in the outer wall that were not well filled after construction, the frames of window and door that were not fitted correctly and the draught seal was deformed, and the check valves at the inlets of the discharge flue and exhaust airway in the house. The tested detached houses were ranked by their airtightness performance. The total joint length of the opening part of the windows and doors was estimated for each detached house and a linear correlation between the n 50 and the joint length of the opening part of the windows and doors was examined. [ABSTRACT FROM AUTHOR]

Adequate airtightness levels are fundamental for the indoor environmental quality and energy efficiency of buildings. The quantitative characterization of expected leaks of common building elements is useful for practitioners that intend to improve building enclosures for airtightness optimization. This study intends to contribute to the quantification of the permeability of windows with a focus on the Southern European context of low airtightness in heavy construction buildings, where windows play an important role. A large experimental investigation was therefore carried out in 23 spaces, establishing three possible set-ups (nothing sealed, window sealed and window and roller-shutter sealed), using the fan pressurization method. A total of 104 tests were performed. Results revealed that the windows’ permeability indices ranged from 4.8 to 96.4 m 3 /(h m 2 ) and from 1.2 to 30.8 m 3 /(h m), with average values of 28.7 m 3 /(h m 2 ) and 8.9 m 3 /(h m), the roller-shutter contribution can be highly variable; also the year of construction, the frame material and the opening system are the key parameters for the airtightness of windows. [ABSTRACT FROM AUTHOR]

Given the high impact that air leaks have on buildings’ energy expenses, most developed countries have set out norms which regulate their presence in homes. Chile will soon begin this process; however, the airtightness revision strategy in envelopes has not been resolved as of yet. This article presents a tool to Assess Airtightness in Design, EHeD. The software will allow predicting the performance of homes under the regulations which will be set out, aiding designers, builders or owners to make decisions when making changes to improve airtightness. EHeD has been validated through pressurization tests in diverse homes across the country, with results that are in line with expectations, thus validating its calculation model. The methodology considers three stages: determining the main factors that have an impact on the airtightness in Chilean homes, preparing an airtightness database for each component (wall, windows and doors) and preparing a calculation model that is integrated in an IT interface. [ABSTRACT FROM AUTHOR]

The article presents the results of the research concerning tightness in the single family houses with superior energy. The first part contains of the main requirements for the tightness of the building contained in the Polish norms, European standards and National Fund for Environmental Protection and Water Management. In order to reach conclusions quantitative and qualitative research of tightness of the buildings energy-efficient and passive single family houses have been conducted. Test procedure was based on the PN-EN ISO 9972:2015. The results indicate in some buildings deviations from the requirements specified in the standards. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the reliability of building energy performance methodology and to determine the significance of the building air tightness. This paper presents a study on the significance of the building air tightness for 27 single-family detached houses, which were built in Central Lithuania during 2007–2011. Results of the field study and calculations indicated that air tightness of A class buildings corresponded to regulation requirements, ACH50 ≤ 0.6 (air changes per hour at a 50 Pascal pressure difference between interior and exterior). There was a large variation in respect of B and C class buildings. The 90% confidence interval of ACH50 value was between 4.17 and 8.05. The results showed that Lithuanian buildings of B and C energy performance class were not sufficiently tight. The average the air change rate, when air pressure of 50 Pa was present, was 2 times higher than the regulatory value (ACH50 = 3 air change per hour). This work presents the ACH50 values' distribution according to the qualifying indicator Cq for A, B, C class buildings. Part of the presented ACH50 values of B class buildings are close to the value applicable to C class buildings. When air tightness of the buildings is evaluated, B energy performance class buildings can turn out to be C class. Results of an existing building's energy performance calculations are reliable only after verifying that the building is air tight. Otherwise, the actual heating energy consumption in buildings can significantly differ from the value calculated as per regulations if air tightness is ignored. [ABSTRACT FROM AUTHOR]

The aim of the paper is to highlight the problem of the seeming air tightness of construction partitions in buildings. In many cases, construction partitions meet the criteria for required air tightness. There are no cross air channel flows through a building envelope, and the Blower Door test is positive, which points to an airtight construction, but the building demands more heat than that due to calculations. The reason for this problem is in wind washing the porous and fibrous materials embedded in the building envelope. Seeming air tightness may be one of the most important reasons why, in construction partitions with the required thickness of thermal insulation, the heat transfer coefficient exceeds the limit value. [ABSTRACT FROM AUTHOR]

In European countries, because of low fossil fuel reserves, energy saving is one of the primary research goals in every energy consumer sector. In the last several years, several directives were elaborated by the European Commission to enhance the energy efficiency in buildings and increase the use of renewable energy sources. In European countries with temperate climates, in a residential building with a "traditional" insulation of the envelope, heating represents approximately 65 to 75% of the total energy consumption. Nevertheless, in educational or office buildings, the energy consumption for ventilation and cooling is notably high. The energy consumption for cooling is strongly influenced by the cooling degree day, which varies year by year. This paper presents the analysis of cooling degree day variation in the last five years in Debrecen and the summer overheating in an educational building before and after refurbishment. [ABSTRACT FROM AUTHOR]