Building Airtightness Research Articles

Airtightness of Buildings in Poland

Implementation of the European Energy Performance of Buildings Directive (EPBD) introduced the first legal airtightness regulations into the 2008 Polish Building Codes. Unfortunately these provisions are currently not sufficiently precise or developed in relation to testing procedures to ensure appropriate airtightness. Generally there is a low level of awareness, experience and knowledge among architects, designers, investors, contractors and there are no certification requirements imposed for measurement companies. Currently there has been little incentive to construct airtight buildings but this could improve with new initiatives. It is concluded, that with the right encouragement, even small buildings can be constructed to tighter values than the currently required n50 value of 1.5 air changes per hour (ac/h). In larger buildings n50 values between 0.3 and 0.5 ac/h can be achieved quite easily. Unfortunately much work is hampered by a lack of specialist knowledge and because measurements are not compulsory. This paper presents a general overview of the building airtightness requirements and measurement issues in Poland. Some representative airtightness measurement data are presented for available residential and commercial buildings.

Analysis of U.S. Commercial Building Envelope Air Leakage Database to Support Sustainable Building Design

In 1998, NIST published a review of commercial and institutional building airtightness data that found significant levels of air leakage and debunked the “myth” of the airtight commercial building (Persily, 1998). Since then, NIST has expanded and maintained a database of whole building envelope leakage measurements of U.S. commercial and institutional buildings. In addition to building leakage values collected from research publications, low-energy building programs and private pressurization testing firms, the database includes basic building characteristics such as year built, building type, floor area, number of storeys, location, and wall construction type for many of the buildings. The purposes of the database are to support the design and construction of low-energy buildings, to establish default values for building simulation, to estimate the energy savings potential of airtightness requirements in standards and codes, and to identify opportunities for additional improvements in building airtightness performance.The U.S. commercial building envelope leakage database contains data for almost 400 buildings including about 70 constructed in the past decade. The average air leakage for the buildings is 20% tighter than the average for the 228 buildings included in a similar 2011 analysis. The data were analysed to determine the factors that impact airtightness such as building type and height. Recent additions to the database include numerous buildings constructed to meet the specifications of sustainable building programs such as the U.S. Green Building Council’s LEED rating system, as well as buildings designed and constructed with air barriers. The analysis found that the 79 buildings with an air barrier had an average air leakage almost 70% less than the average for the 290 buildings not specified as having an air barrier thus demonstrating the critical need to design and construct commercial buildings with an air barrier to support sustainable building design.

The Influence of Construction Fillings of Building on Airtightness

Construction fillings of buildings such as windows, doors or gates are very often the cause of the increased energy balance of buildings. Especially for energy efficient buildings are windows and doors the weakest parts of the building. Low quality connection of filling construction to a building structure leads to undesirable air leakage, formation of cracks and joints. Joints and gaps reduce the airtightness of buildings, increase energy consumption and reduce the operating efficiency of mechanical ventilation with heat recovery system. The main objective of contribution is to describe and analyze the impact and solution to fillings of buildings on airtightness of energy-efficient buildings.

Diagnostics of Current Developments in the Field of Building Airtightness

One of the basic principles of energy efficient buildings in accordance with sustainable development is perfectly airtight building envelope. Oversized heat loss through the building envelope leakage adversely affects the energy balance of buildings. The paper provides diagnostic of the recent developments in airtightness of buildings using qualitative method. The aim of this paper is to draw conclusions - dependences, definitions of weak and strong points of the process, their causes and consequences.

Health impacts due to personal exposure to fine particles caused by insulation of residential buildings in Europe

The insulation of residential buildings affects human exposure to fine particles. According to current EU guidelines, insulation is regulated for energy saving reasons. As buildings become tighter, the air exchange rate is reduced and, thus, the indoor concentration of pollutants is increased if there are significant indoor sources. While usually the effects of heat insulation and increase of the air-tightness of buildings on greenhouse gas emissions are highlighted, the negative impacts on human health due to higher indoor concentrations are not addressed. Thus, we investigated these impacts using scenarios in three European countries, i. e. Czech Republic, Switzerland and Greece. The assessment was based on modelling the human exposure to fine particles originating from sources of particles within outdoor and indoor air, including environmental tobacco smoke. Exposure response relationships were derived to link (adverse) health effects to the exposure. Furthermore, probable values for the parameters influencing the infiltration of fine particles into residential buildings were modelled. Results show that the insulation and increase of the air-tightness of residential buildings leads to an overall increase of the mean population exposure – and consequently adverse health effects – in all considered countries (ranging for health effects from 0.4% in Czech Republic to 11.8% in Greece for 100% insulated buildings) due to an accumulation of particles indoors, especially from environmental tobacco smoke. Considering only the emission reductions in outdoor air (omitting changes in infiltration parameters) leads to a decrease of adverse health effects. This study highlights the importance of ensuring a sufficient air exchange rate when insulating buildings, e. g. by prescribing heat ventilation and air conditioning systems in new buildings and information campaigns on good airing practice in renovated buildings. It also shows that assessing policy measures based on the exposure may provide different recommendations compared to an assessment based on only the outdoor air concentration.

The Presence of Volatile Organic Compounds (VOCs) Indoors During the Heating Season: in situ Emission Study of a Frame-house

Due to the more stringent energy regulations the air-tightness and insulation of buildings is much higher than in old buildings. As a result of synthetic building materials and reduced air exchange rates indoor air quality is deteriorating significantly. In this study we examined the indoor air quality of a newly built, frame-house during the heating season. Formaldehyde (11-130 μg/m3), 3-carene (133-300 μg/m3) and alpha-pinene (130-300 μg/m3) values varied over a wide range depending on the indoor activities. We determined that further measurements are required on the subject during the summer period as well.

Experiences from nine passive houses in Sweden – Indoor thermal environment and energy use

This paper presents experiences from a recently built area with passive houses in Linköping, Sweden and compares them with conventional buildings, mainly from an indoor environment perspective, but also based on energy use. The built area consists of 39 recently constructed terraced houses, of which nine are built according to the passive house standard. The aspects of thermal comfort as well as local discomfort are studied. The methodology is based on on-site measurements and two types of simulations – CFD and Building Energy Simulation. In addition a post-occupancy evaluation was made using a standardized questionnaire to relate the occupant's perception of the indoor environment one year after the buildings were completed.The thermal comfort for these newly built passive houses is well within the limits in the local building code. However, some interesting findings related to local comfort such as cold floors are found in the post-occupancy evaluation as well as in the predictions. The occupants of the passive houses experience cold floors to a higher degree than in the conventional buildings. It was also shown that there are a higher number of complaints related to high temperatures during summer in the passive houses. It is worth noting that the buildings do not have external shading installed by default. The effect of varying temperatures was also observed in the passive houses to a higher degree than in the more conventional buildings, especially related to cooking and other heat-generating activities, which is normal in a more well insulated and airtight building.

The IVAIRE Project - Ventilation Characteristics of Single Family Homes of Asthmatic Children Followed in an Asthma Clinic

Background and Aims The IVAIRE study evaluated the impact of improved residential ventilation on IAQ and the frequency of asthma symptoms in children. This paper describes the pre-intervention phase of this study where the ventilation characteristics of the single family homes were analyzed in order to select the homes participating in the ventilation intervention. Methods Between October 2008 and June 2010, 111 children were selected and their homes were visited three times by trained technicians during the heating-season (fall and winter) and summer. During these visits the ventilation rates were measured and the mechanical ventilation system (MVS) and their use were characterized. The measured ventilation parameters were the air changes per hour (ACH) measured with PFT gas, the building airtightness (ACH50) with a blower door, CO2, and relative humidity (RH). Ventilation parameters were compared according to the presence/absence and the type of MVS. Results A MVS was present in 73 of the 111 homes, of which 44 were heat recovery ventilators (HRV) and 29 had mixing boxes. There was no difference in ACH between the homes with (0.22) or without (0.20) a MVS (p=0.53). However, the ACH50 was lower in the homes with a MVS than without (3.1 vs. 4.8, p=<0.0001) as well as RH (37.6 vs. 42.3%, p=0.0009). Moreover the homes with an HRV had a higher ACH (0.25 vs. 0.18, p=0.003) and a lower RH (35.8 vs. 40.4%, p=0.002) than the homes with a mixing box. Conclusions Even though in the homes with a MVS an HRV seems to be more effective than a mixing box, the ACH remained lower than the ASHRAE recommended guideline of 0.35 h-1. This indicates that the presence of a MVS alone may not guarantee adequate ventilation. Factors such as the capacity of the ventilation unit, proper installation and utilization by occupants need to be investigated to design specific corrective interventions tailored to each home.

Influence of Building Materials on Building Airtightness

The aim of the contribution is to confirm or rule, by using non-parametric Kruskal Wallis test, the hypothesis published [1] that the construction type and building materials have not statistically relevant effect on the final building airtightness. For non-parametric test is used the same sample as in [1], where the impact of construction type on the airtightness is refused by using parametric test - one way analysis of variance (ANOVA).

Airtightness of Energy Efficient Buildings

Airtightness of Energy Efficient Buildings

Tracer gas technique for measurement of air infiltration and natural ventilation: case studies and new devices for measurement of mechanical air ventilation in ducts

In buildings without mechanical ventilation, the fresh air needed by the occupants is supplied only by air infiltration or natural ventilation. Its quantification by analytical methods is difficult, and so experimental methods such as the tracer gas technique are very useful. In this work, several case studies are presented, where one may see the potential of this technique to detect small differences in building air tightness, due to different envelope elements, namely the type of window frames and location of blinds' boxes. The applicability of this technique to other spaces rather than buildings can also be analyzed. When dealing with mechanical ventilation, it is difficult to measure the duct air flow rate precisely, because of the minimum duct length necessary to obtain a good mixing of the tracer gas with the air, when conventional probes are used. Research was carried out with the development of new probes to overcome this situation, and results are also shown. With accurate measurements of air flow rates, it is possible to reduce CO2 emissions due to air heating or cooling in buildings.

Airtightness of Buildings in Slovakia

The actual trend of civil engineering leads to quality improving of housing and to saving of all participated energies. Airtightness of buildings´ envelope constructions has an important job in the point of view of energy savings and energy economy. Undesirable air flow occurs through joints, cracks and leaks in building envelopes. It has a significant influence to final quality of an indoor environment and energy demands and needs of warmth for heating resulting from it. The paper presents results of chosen airtightness measurements made in family and apartment buildings in the Slovak Republic, the achieved level of airtightness by various construction systems and outer walls, as well as which impact for air changes has location and selection of materials used for airtightness layer in the construction of outer walls at pressure difference of 50 Pa (n50).

Assessment of the air change rate of airtight buildings under natural conditions using the tracer gas technique. Comparison with numerical modelling

Under natural conditions, air change rates are very sensitive to specific building elements and to climate conditions, even more so in the case of airtight buildings. Consequently, applying general correlations to such cases may lead to inaccurate predicted air change rates. Still, this approach remains valuable because of its simplicity compared to other methods such as wind tunnelling and CFD simulations. In this paper, the tracer gas concentration decay technique was selected to contribute additional information to classical air-tightness measurements. The measurements were used to fit the coefficients of a general single-node pressure model. Simulation results were found to be consistent with tracer gas measurements most of the time. However, the closeness of the fit is strongly related to the average pressure coefficients from the literature, which were estimated more precisely using the other techniques mentioned above. From a general point of view however, it would seem promising to extend this method to other buildings.

Influence of Air-tightness on Heat Energy Performance in Post and Beam Building with Exposed Wood Frame

Han-green building is one of the modernized Korean traditional buildings developed by Korea Forest Research Institute. This building was developed to increase the competitiveness of Korean traditional building using state-of-art technologies; hence Han-green building has the inherent characteristics of traditional building such as exposed wood frame in wall. Because of discontinuity in wall by the exposed wood frame, there is a concern on heat-air leaking in terms of energy performance. In this study, air-tightness of Han-green building was evaluated to investigate the influence of gaps between frames and in-fill walls. Blower door test was carried out to evaluate the air-tightness, and air-change rate (ACH50) was evaluated by averaging four set of pressurization and depressurization test. The air-change rate of Han-green house was 5.91 <TEX>$h^{-1}$</TEX>. To improve energy performance of Han-green house, thermal infrared images of Han-green house were taken in winter with heating to find out where the heat loss occurred. It was found that the building lost more heat through gaps between frames and in-fill walls rather than through other parts of this building. After covering all the gaps by taping, the blower door test was performed again, and the air-change rate was improved to 5.25 <TEX>$h^{-1}$</TEX>. From this analysis, it was concluded that the heated air can leak through the gaps between frames and walls. Therefore, when one designs the post and beam building with exposed frame, the detail design between frame and wall needs to be carefully dealt. However, Han-green building showed relatively high air-tightness comparing with other country research results.

Energy vs. ventilation rate in buildings: A comprehensive scenario-based assessment in the European context

This work performs a comprehensive characterization of the relation between energy use and ventilation rates in both residential and services buildings in the diversity of European climates. Through detailed building simulation, a sensitivity analysis was performed considering four building types (detached house, apartment, office and school), three climates/locations (Helsinki, Paris and Lisbon), three heating and cooling setpoints settings, four air-flow control strategies, usage of heat recovery coupled with four different building airtightness conditions, and three ranges of humidity control. The impacts of changing ventilation rate (ICV) were determined for each case as being the slope of the energy needs as function of the ventilation rate, in the range of 0–50m3/(hperson). The energy results, assessed through dynamic building simulation, show that changing ventilation by 1m3/(hperson) with current practice systems has an impact in total HVAC-related final energy demand between 0.3 and 0.6kWh/(m2year) depending on building type and location. However, with advanced systems the ICV values could become close to 0.1 [kWh/(m2year)]/[m3/(hperson)] in most cases analyzed. These results can be used to assess the energy impacts of IAQ polices, including hypothetical trade-offs between health and energy or different degrees of use of the precautionary principle.

Feasibility assessment of passive cooling for office buildings in a temperate climate through uncertainty analysis

In this paper, the feasibility of passive cooling in newly built office buildings in the temperate climate of Belgium is assessed using the standardized adaptive comfort criteria. This is done through Monte Carlo uncertainty analysis of the simulated weighted exceeding time for different building designs with varying insulation level, glazing-to-wall-ratio, glazing type and air tightness. Two passive cooling schemes are studied: diurnal manual window operation and the combination of diurnal manual window operation and passive night ventilation. Additionally, two possible measures to limit heat gains, external solar shading and daylighting, are considered.The integration of a detailed model of window operation, establishing a real-time coupling between the thermal model and the behavioural model and thus allowing simulating adaptive behaviour, is shown to impact the results significantly and is therefore recommended by the authors.The uncertainty analysis shows that it is possible to cool office buildings solely by diurnal manual window operation, even for highly insulated and air tight buildings. This requires minimizing heat gains to about 900 kJ/m2 per working day during summer months. When a combination of diurnal window operation and night ventilation is available, limiting the heat gains to about 1500 kJ/m2 per working day suffices.

Sustainable Developments for Future Building

Welcome to this special issue of Indoor and Built Environment. This special issue of journal papers is based on the advanced research studies that had been carried out by the Center for Sustainable Healthy Buildings (CSHeB) in Korea. The 20 papers in this special issue of Indoor and Built Environment were selected from a symposium presentation held on February 10, 2011, in Seoul, South Korea. These papers were further developed by the authors and peer reviewed by experts. The International Society of the Built Environment (ISBE) is proud to be associated with this special issue and recommend you to study the papers presented. ISBE shares the same missions and beliefs with the CSHeB of Korea. We hope by our disseminations, we may contribute to the further advancement of innovative technologies for sustainable built environments; better designs that will improve health and wellbeing for everyone and an influence on policies and planning for sustainable development of healthy buildings for all cultures and nationalities. CSHeB has become one of the leading research organizations in all the subjects concerning the built environment, emphasizing the need for interdisciplinary research into architectural, medical, psychological, physiological, social and environmental aspects of healthy buildings. Progress has been made in understanding the need for social integration, design, construction, maintenance and occupants’ requirements for development of sustainable and healthy buildings. A number of reports and studies have been published providing the latest ‘‘state-of-the-art’’ dissemination of research relating to lighting, ventilation, social environment, indoor air quality, acoustics, thermal comfort, moisture and structure for the built environment. The main focus of this special issue of papers was on the sustainable developments required for future building and considering the need for a future society with an increasing portion of elderly to relative young population, and also the governments’ demand for energy-efficient buildings with low carbon emissions. There is a need to consider the implication to building design and planning to accommodate and to provide a proper provision for the aged and to ensure how healthy environments can be achieved within low-carbon architecture, to satisfy the occupants’ requirements for comfort, environmental quality and minimization of environmental harm that could affect the health and wellbeing of people living and working in these future built environments. This special issue is of interest to broad interdisciplinary readers including academics, practitioners and consultants. Sustainable development and sustainable buildings are important part of architecture and governments’ guidelines and building regulations in many countries of the world. Many governments of the world including the UK and Europe, Korea, Japan and China are setting targets for reduction in carbon emissions and therefore higher energy efficiency standards in buildings and this has an important implication on the materials used due to the embodied carbon, ventilation and indoor air quality requirements due to increasing air-tightness of buildings and more efficient lighting systems and a control of glare. There is also the consideration to look after our elderly, so they will be able to live with dignity with adequate provision for their care and needs within a holistic, healthy community such as in Korea.

Experimental analysis of air tightness in Mediterranean buildings using the fan pressurization method

Building air tightness plays an important role both on the energy saving and the indoor thermal comfort. Several studies in recent years have been carried out in US and in northern Europe, usually under cold climatic conditions, whereas Mediterranean buildings are not deeply investigated in literature.In this paper the authors present the results of an experimental study carried out on residential buildings located in southern Italy using the fan pressurization method, also known as “blower door test” (BDT). In particular, the main metrological aspects in air tightness measurement of buildings and the influence of air leakage on energy consumption and indoor comfort in different architectural typologies typical of the Mediterranean area are focused.The experimental results presented can give some interesting suggestions to improve the measurement uncertainty in BDT and to better detect energy and environmental criticalities in the building audits.

Low-Carbon Housings and Indoor Air Quality

The purpose of this paper is to provide a review of the background information regarding low-carbon housings in the United Kingdom and to raise the concern of the possible high indoor pollution load due to the emissions from building materials and combustion products which would adversely affect the indoor air quality in air-tight buildings, especially homes. The standard guidelines given by the Building Regulations in the UK are reviewed especially in relation to mechanical ventilation with heat recovery systems. Also research literatures in relation to heat recovery ventilators and the use of air-cleaners from Korea, Hong Kong and China and from Europe are also included to illustrate the various possibilities to conserve energy and to achieve adequate ventilation with an improvement of indoor air quality. The effectiveness of using a heat recovery ventilator system and trickle ventilators in unoccupied super-energy-efficient test houses is illustrated by reviewing the long-term indoor volatile organic compound (VOC) concentrations in these test houses. The awareness of the issue is important for the future design and indoor air management of buildings, so as to provide adequate ventilation for living spaces without costing too much on energy efficiency.

Reconsideration of parameter estimation and reliability evaluation methods for building airtightness measurement using fan pressurization

Building airtightness is among the most important performance indices of healthy indoor air quality, condensation, the building stack effect, and heating and cooling load caused by infiltration. Performance parameters are usually measured by testing methods involving pressurization or depressurization by means of a mechanical fan. Similar testing standards have now been established in ISO, ASTM, and JIS. All methods entail finding two parameters from some measurements of the inside and outside pressure difference and the airflow rate. Although these measurement data analysis methods are described in informative annexes, these are important techniques and have problems to be reconsidered and solved as a stochastic estimation and uncertainty evaluation. In the present paper, we examine improvement using weighted least-squares, correction of the parameter estimation equation, and deduction of the uncertainty propagation equation from not only the measurement uncertainty but also the residual of the model equation. Also, a reliability evaluation index capable of checking the appropriateness of the measurement is proposed. Through a computational experiment, the precision of the estimated parameters, the uncertainty of these parameters, and the reliability indices are investigated. Further, the present method is applied to actual measurement data and its practicality is also verified.