Fan Pressurization Method Research Articles

Model-Scale Reproduction of Fan Pressurization Measurements in a Wind Tunnel: Design and Characterization of a New Experimental Facility

In many countries, building airtightness is mandated by national regulations or energy efficiency programs, necessitating accurate measurements using the fan pressurization method. Given the significant influence of wind on measurement uncertainty and the need for reliable regulatory tests, experimental studies in a controlled environment are needed. This paper presents a novel experimental facility designed to replicate fan pressurization measurements on a model scale under controlled laboratory conditions. The key features of the facility include the ability to (1) conduct fan pressurization measurements, (2) generate steady wind conditions across varying wind speeds, and (3) accurately measure parameters like the pressure difference, wind speed, and airflow rate. The experimental facility includes a pressurization device, a wind tunnel, and a model representing a two-story house with nine distinct leakage distributions. A total of 96 fan pressurization measurements were executed using this setup, adhering to the similarity conditions specifically defined for assessing airflow errors due to wind. These tests followed the ISO 9972 standard, with the pressure differences ranging from 10 Pa to 100 Pa and steady wind speeds from 1 m·s−1 to 7.5 m·s−1. This experimental facility marks a significant advancement in understanding the effect of wind on building airtightness measurements.

In Situ Airtightness Measurement Using Compressed Air Flow Characteristics

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.

Experimental Study of Envelope Airtightness in New Egyptian Residential Dwellings

In residential buildings, air infiltration impacts energy, indoor air quality, and thermal comfort considerably. While air infiltration in residential buildings has been the focus of many studies, most published field-testing results pertain to developed countries, with little or no data on air infiltration in developing nations. This paper presents the results of one of the first field investigations into envelope infiltration in the residential buildings of the hot-arid climatic area of Egypt. To analyze the air permeability of the building envelope, the fan pressurization method, often known as the blower door test (BDT), is used, following ISO 9772. The study focuses on 20 residential dwellings built with heavy construction materials and subjects them to extensive characterization and testing. The average air leakage and the air permeability rate for the tested sample were 6.14 h−1 and 17.3 m3/(h∙m2), respectively. However, significant variations in airtightness were observed across the dwelling, leading the team to test several building-related parameters statistically to study their impact on airtightness. Fenestration quality appeared to be a critical factor in determining air infiltration, showing a strong correlation with the air change and leakage. A further investigation underscored that the specific aperture factor and the fenestration quality can predict the infiltration rates to a large degree. Thus, we recommend further investigation of these characteristics in heavy construction material building. Finally, we strongly recommend that building codes in developing countries such as Egypt include minimum performance requirements for fenestration.

An Analysis of ACHn for Improving the Performance of Green Remodeling through the Airtightness Measurements

Purpose: The study analyzed the airtightness of several buildings which were constructed more than 30, 20, 10 years ago and recently constructed by using various air leakage metrics. In addition, the various ACHn values were estimated in which it is not possible to maintain the reference pressure difference of 50 Pa due to some building conditions such as aged or large volume. Moreover, the relationship between the values of ACH 50 and ACHn was analyzed. Method: Two rooms in four different buildings were chosen and the air leakage rates were measured by using the fan-pressurization method based on ISO Standard 9972. For the measurement, both pressurization and depressurization test modes were applied twice. Various airtightness metrics were analyzed for the air leakages in each room. Result: The biggest air leakages were observed in the oldest building in which the ACH50 value was 24.35 h<SUP>-1</SUP>. Similar air permeability values were observed between the rooms in the buildings. Therefore, this metric can be used as a representative air leakage rate for the whole building. Moreover, the conversion coefficient for the ACHn values at different pressures from 4 Pa to 75 Pa based on the ACH50 value was estimated.

DETERMINATION OF VENTILATION HEAT LOSSES THROUGH BUILDING ENVELOPE – A CASE STUDY

&amp;lt;jats:p&amp;gt;In this paper the experimental procedure for the determination of ventilation heat losses across building envelopes has been shown. The alternative name for this method is Blower Door Test or Fan Pressurization method. This text is a user manual for the determination of ventilation heat losses and parameters which is used to describe the air permeability of buildings. The experiment examination was performed at the office with old and after with new windows. The results were compared, and a significant contribution of new windows was shown.&amp;lt;/jats:p&amp;gt;

Quantification of air leakage paths: a comparison of airflow and acoustic measurements

Today, the fan pressurization method is the most frequently used method to evaluate a building's airtightness. However, the localization and quantification of leaks remain difficult. In this paper, an acoustic method is introduced to estimate the leakage size of single leaks. Acoustic and airflow measurements were conducted and compared in laboratory tests within the same boundary conditions. This work aims to investigate if various leak sizes can be predicted using acoustic measurement methods. The test apparatus consists of two chambers, separated by a test wall. This wall represents a single characteristic air leakage path. Various types of wall structures with different slit geometries, wall thicknesses, and insulation materials were investigated. The acoustic measurements were performed with a sound source placed in one chamber and ultrasonic microphones located in both chambers. These results were compared to measured airflows through the test wall to provide estimates of uncertainty in the acoustic approach, which indicate a linear trend. Finally, these laboratory measurements were compared to the same measurements at a real office building. Although the acoustic measurement uncertainty is still significant (greater than +/- 50%), the acoustic method has the potential to give an order of magnitude of single leak sizes.

Airtightness of buildings – Assessment of leakage-infiltration ratio and systematic measurement error due to steady wind and stack effect

The fan pressurization method that is widely used to measure the airtightness of buildings is known to have quite large measurement error. It is made up of random measurement error (precision) and systematic measurement error (bias).The first part of the present article explains, with analytical evidence, why steady wind and stack effect generate systematic measurement error and it assesses this error through Monte Carlo simulations. Tables with practical results are provided for common zero-flow pressure difference intervals. For example, they show that with a typical zero-flow pressure difference of 5 Pa, the systematic measurement error at a reference pressure difference of 4 Pa is in the order of −1,1% to −2,2%. Possible improvement of the test method is also suggested and assessed.The second part of this article calls on the Monte Carlo simulations to assess the variability of the leakage-infiltration ratio. A simplified analytical formula has been developed to allow comparison and it shows very good correlation. Tables with practical results are also provided. For example, they show that the well-known value of 20 can be associated with a natural pressure field of [−3 Pa; +3Pa].

Improving air leakage prediction of buildings using the fan pressurization method with the Weighted Line of Organic Correlation

In many countries, the fan pressurization method is the most frequently chosen approach for measuring the air leakage of houses. The measurements are usually performed at pressures that far exceed pressures to which buildings are exposed to under normal conditions. A fit of these tests to the power-law formulation allows an extrapolation to data points outside the measured pressure range. With the Ordinary Least Square (OLS) fitting method, the pressure exponent and flow coefficient can be determined. However, the measurement results are highly sensitive to uncertainties induced by external factors like changing wind conditions during the tests, which is neglected by OLS. This may lead to errors in the prediction of flows at lower pressures. The Weighted Line of Organic Correlation (WLOC) is an alternative approach and takes measurement uncertainty into account.In this paper, a statistical analysis of an extensive data set of pressurization measurements has been performed. Both regression techniques have been compared for almost 7500 fan pressurization measurements of six houses in 109 different house leak configurations. The variability in predicting pressure exponent and flow coefficient for both WLOC and OLS regression was analyzed using probability density functions. It was found that the Weighted Line of Organic Correlation significantly decreases the uncertainty in predicting pressure exponent, flow coefficient, and other low-pressure air leakage metrics compared to the Ordinary Least Square fitting. The authors highly recommend the implementation of WLOC in current measurement standards and test equipment.

Models for Determining Air Permeability of Buildings by Fan Pressurization Method

The fan pressurization method in ISO9972:2015 (ISO method) aims to determine the air permeability of buildings. We focus on the effective leakage area (ELA) which is the most typical quantitative parameter of air leakage among a variety of parameters and variables obtained by the method. Herein, we clarify the relation between the ELA and the geometrical area and how a group of leakages are combined to an equivalent leakage. Models expressing the relation include a coefficient. The models provide both the leakage area with the equivalent total area of widely distributed narrow rectangular leakages and the large circular area or wide rectangular leakages located nearby by adjusting the coefficient. The coefficient is estimated to fit the models to the ELA estimated by the ISO method. The coefficient is approximated using the value of $\pi $ or $\pi \mathord {\left /{ {\vphantom {\boldsymbol {\pi } {4}}} }\right. } {4}$ . The ELA of the room itself and that of the room with a size-controllable artificial leakage area are estimated by the ISO method, whereas the given artificial leakage area is discriminated from the ELAs via the models. The area discriminated is well fitted to that set a priori , and is within 2.2%. The error of the geometrical leakage area of the room estimated under different artificial areas of leakages is 2.2%.

Blower Door를 이용한 건물의 기밀성능 시험 방법의 고찰

The airtightness of a building is one of the main factors that affects both the energy performance and the indoor air quality. Fan Pressurization/Depressurization Test using blower door system is the most commonly used method of measuring a buildings’ air tightness. The fan pressurization method was established based on ISO 9972 (KS L ISO 9972)-Thermal performance of buildings-Determination of air permeability of buildings. ASTM E779, CGSB 149.10 and EN 13829 are the other standards used to measure the building air tightness. The basic theory and technique for the definition of the building airtightness using these standards is similar However, test pressure condition range, the correction of the result value and the air leakage rates reporting techniques are different. In this paper, the basic principle, requirements and limitations of these standards are reviewed. The weather conditions for test to eliminate the pressure difference due to wind pressure and indoor/outdoor temperature variations to obtain an accurate airtight performance is reviewed. Similarly, the pressure difference correction method such as “zero-flow pressure difference” for accurate measurement of pressure difference in each standard are described. Pressurization and depressurization methods are used in measurement to eliminate the discrepancy between the two. However, in case the case that only one of the methods is used for airtightness measurement, the results may deviate from the actual airtightness performance of the building components. Likewise, the airtightness performance of building components for domestic high-rise buildings were analyzed through the review of previous research results and the performance compared with the those of similar buildings overseas.

A method to quantify uncertainties in airtightness measurements: Zero-flow and envelope pressure

In airtightness measurements using the fan pressurization method, the calculation of uncertainties does not take into account the zero-flow pressure approximation. It was recently suggested that neglecting the uncertainties related to zero-flow pressure approximation could be an unrealistic hypothesis. In this study, a method for quantifying this source of uncertainty is proposed, illustrated and discussed. The method is applied to a series of 31 zero-flow pressure tests performed on a newly-constructed apartment within a period of 15 days in Brussels, Belgium. For each test, 32 different zero-flow pressure approximations were compared. Since the data had a nested structure, multiple multi-level models were used for their analysis. The results show that, for the tested building, the zero-flow pressure approximation uncertainty is 0.45, 0.91 and 1.52 Pa respectively under low-, medium- and large-wind conditions. These uncertainties can be reduced to 0.42, 0.80 and 1.39 Pa when using longer zero-flow pressure measurement periods. As a comparison, uncertainty in pressure measurement at 50 Pa due to the equipment is 0.25 Pa. The uncertainty of zero-flow approximation makes the envelope pressure uncertainty non-negligible, therefore having an impact on the regression technique used to determine the building airtightness.

Airtightness of electrical, mechanical and architectural components in South Korean apartment buildings using the fan pressurization and tracer gas method

The purpose of this study is to measure airtightness of building components in newly constructed apartment buildings in South Korea. For the measurements, electrical, architectural and two mechanical components regarding water and air systems were categorized and air leakage rates of these parts were measured by the blower door test. In addition to these building components, air leakage rates on the entrance door and three different building heights were analyzed. Moreover, the results obtained by the blower door test were compared with the tracer gas measurements. As a result, the air leakage rates (ACH50) were between 0.7 and 1.0 h−1, when all parts were sealed. When unsealing all parts, the ACH50 values ranged from 1.6 to 2.7 h−1. In addition, the ACH50 values were highly influenced by the entrance door and window systems. By improving the windows and the entrance door, the air leakages can be significantly reduced in residential buildings. Furthermore, the comparison results obtained by the tracer gas and blower door showed that artificially produced pressure difference condition can cause the overestimated ACH value.

Assessing the airtightness performance of container houses in relation to its effect on energy efficiency

This study examines the airtightness performance of four types of commonly-used container houses (CHs) and its impact on their energy efficiency. One of the CHs was treated by sealing all junctions inside the container envelope. The airtightness levels of unsealed and sealed CHs were measured by using the fan pressurization method. The interior surfaces of building envelope were scanned by thermal imaging in order to locate the areas suffering from air leakages and thermal failures. The annual energy consumptions of unsealed and sealed CHs for their heating were predicted by energy simulation analyses. The unsealed CHs have poor airtightness features while performing in Energy Rating B category. The junctions of those houses, especially where wall, slab and roof panels come together and the edges of the openings also suffer from air leakages, thermal bridges and condensation. Sealing the interior surfaces of junctions and edges improves the airtightness level considerably while heat loss and condensation problems at the junctions still continue. An 81% improvement in airtightness performance of the CH Type B provided a reduction of 9.3% in annual energy demand which is not enough to step up its Energy Rating category. The results indicate that airtight jointing is needed at junctions while the use of thermal breaks at junction details has vital importance to eliminate thermal failures and to improve energy efficiency performance of CHs. The combined use of Blower Test Method and Infrared Thermography is useful for non-destructive assessment of airtightness features of building envelopes.

Experimental study on airtightness test methods in large buildings; proposal of averaging pressure difference method

Airtightness measurement standards using the fan pressurization method are widely used for measuring residential units such as detached houses and apartment units. The measurement of airtightness for small buildings can be readily conducted through existing fan pressurization methods. However, it can be difficult to achieve accurate measurement results for large buildings, as the height and volume of the buildings are considerably increased. This paper empirically investigates factors that are to be considered in regard to airflow rate (Q) and pressure difference (ΔP), which are measurement values required for deriving more accurate airtightness values for large buildings. The specifications of the standards ISO 9972, EN 13829, ASTM E779, JIS A 2201, ATTMA TS 1, and CAN/CGSB 149.15 relating to Q and △P are compared. Test conditions with respect to Q and △P are discussed for large building airtightness measurements. In measuring airtightness, a method is proposed in which the pressure difference at each floor of the building is measured and an average pressure difference value is used. Experiments were conducted on two multi-story office buildings using the method based on measuring pressure difference according to existing standards in tandem with the proposed pressure difference measurement method. The results of the experimental study show that the vertical pressure distribution across the overall building envelope can be significantly different when a building is pressurized. The airtightness values may also be different according to the measurement methods. This paper demonstrates how important it is to derive accurate △P values in measuring large building airtightness.

An infrared thermography passive approach to assess the effect of leakage points in buildings

Energy consumption is one of the major concerns of European citizens and governments. In the EU, buildings use 40% of total energy consumption and generate 36% of greenhouse gases. Therefore, buildings energy efficiency must be optimized, which requires, among others, minimizing infiltrations through the envelope. The measurement of the air leakages through a building envelope is usually carried out by means of the fan pressurization method (Blower Door Test). Although useful for assessing the airtightness of buildings no information is obtained regarding the air leakage pathways. For that, other techniques such as infrared thermography (IRT) can be used.This work presents the results of an experimental campaign that aimed to assess the applicability of IRT to detected air leakage through the roller shutter handle and the window frame of a room. A quantitative approach for results analysis was implemented and the contribution for airtightness of both roller shutter handle and window frame was also evaluated using the Blower Door Test.It was possible to conclude that the window frame had a larger contribution to the air flow rate than the roller shutter handle (109.4m3/h and 21.7m3/h, at a pressure difference of 50Pa). Qualitative analysis of the thermal images indicated that a colder area near the leakage point can be detected and that it grows with the increase of the pressure difference. The quantitative approach showed that a stabilization of the surface temperature close to the value of the outdoor temperature occurred and the relative differences are around 15% both for the window frame and the roller shutter handle. It also showed that, in most cases, the first pressure step (ΔP=25Pa) is responsible for about 60% of the differences in the superficial temperature. A good correlation was found between the proposed Pressurization Thermal Index and the temperature gradient between the exterior air temperature and the initial superficial temperature (ranging from 0.74 to 0.82).

A contribution for the quantification of the influence of windows on the airtightness of Southern European buildings

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 96.4m3/(hm2) and from 1.2 to 30.8m3/(hm), with average values of 28.7m3/(hm2) and 8.9m3/(hm), 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.

Experimental Air-Tightness Analysis in Mediterranean Buildings after Windows Retrofit

Energy saving and Indoor Air Quality (IAQ) in buildings are strongly affected by air leakages. Several studies reveal that the energy loss owing to leaky windows can account for up to 40% of the total building energy demand. Furthermore, at the design stage, the possible infiltration of outdoor air through windows is not taken into account when determining the nominal outdoor airflow rate of the ventilation system. This practice may result in an oversizing of the ventilation system and consequent energy waste. Thus, the air-tightness class of a wall assembly should be assessed for each window component considering the type of material, the presence of the seal, the type of closure, the sealing and the maintenance condition. In this paper, the authors present the experimental results of air-tightness measurements carried out using the fan pressurization method in three residential buildings located in the Mediterranean region before and after a window retrofit. Two different window retrofits were investigated: the application of rubber seals on window frames and the substitution of existing windows with new certified high performance windows. The effectiveness of such retrofits was estimated also in terms of energy saving. Test results demonstrated a high variability of the building air tightness after window retrofits, despite the fact that air tight–certified windows were used.

Air Permeability of Naturally Ventilated Italian Classrooms

The study is focused on the evaluation of air permeability and ventilation rate in Italian classrooms. Measurements were performed in 16 naturally ventilated classrooms located in Cassino, Central Italy. Classrooms’ airtightness was evaluated through the fan pressurization method. Air exchange rates where both estimated from the blower door results and measured using a CO2 decay test method. The effect of the periodic manual airing of the classrooms (through window and door opening) was also investigated performing CO2 and particle number concentration measurements during the school time.

Infiltration rate performance of buildings in the historic centre of Oporto

This work is part of a major investigation the authors are undertaking aiming to evaluate the energy performance of different retrofitting strategies for housing buildings, in order to establish preferential criteria of intervention according to its climate zone location, morphology, constructive features and patrimonial values. In the historic centre of Oporto, one of the major actions resides on a significant reduction in the heating loads of these distinctive buildings by decreasing the windows infiltration rate. To be able to accurate this potential for energy savings, in situ measurements of the infiltration rate of this houses at present were required, previous to a possible intervention. This article presents the data obtained using a fan pressurization method in two non-refurbished characteristic buildings of the Oporto’s Historic Centre, and analyses the results obtained for both a typical sash window and a casement window. Some relations between these infiltration rates and the buildings morphological and typological characteristics are considered.

건물 출입문의 기밀성능 기준 및 측정을 통한 데이터 비교

Airtightness is a key factor for saving building energy. The importance of the entrance door airtightness has been increased because the importance of the whole building airtightness has been increased. In this study, we investigated domestic standard and international ones of entrance door airtightness to establish criteria of entrance door airtightness. We reviewed various measured airtightness data in the previous studies. Also, we conducted field measurements for several entrance doors - types were such as the swing, sliding, and revolving doors installed existing buildings. Fan pressurization method was used for the measurement based on ASTM E783/ASTM 2283 standard. We made an comparative analysis on the field measured data with the measured ones of other countries.