Airtightness Levels Research Articles

Reducing inter-unit pollutant transfer through multifamily unit compartmentalization

Compartmentalization, which refers to air sealing each unit within a building from the exterior and other interior spaces, has been proposed as a strategy to improve indoor air quality and energy efficiency in multifamily buildings. This study collected field data on air tightness and pollutant transfer in three new-construction multifamily buildings in California, which was used to develop a model in CONTAM that simulated the impact of leakage levels, ventilation strategies, and climate zones on inter-unit pollutant transfer in multifamily buildings. Air leakage testing found an average total unit leakage of 0.8 L/s50/m2, almost twice as tight as California’s current compartmentalization requirement (1.5 L/s50/m2). Two buildings designed with balanced ventilation systems were measured to have imbalanced continuous unit ventilation flows, which were further imbalanced by intermittent exhaust fan operation. Tracer gas testing in two buildings indicated that only about 1–3% of the total air entering a unit came from each neighbouring unit. Furthermore, all particles were apparently removed along the way, as there was no observable particle matter transfer at the tested air tightness levels (0.6–0.9 L/s50/m2). Modelling results indicated that leakier units led to greater dilution of pollutants generated within the unit but increased gaseous pollutant transfer from neighbouring units. The average concentration of benzene, a proxy gas for cigarette smoke, transferred into non-smoking units from neighbours who did smoke almost doubled, surpassing acceptable exposure levels, in the leaky simulation (2.3 L/s50/m2) compared to the tight simulation (0.8 L/s50/m2). Overall, this study suggests that stricter compartmentalization requirements should be adopted in multifamily building code updates, as tighter requirements appear to be manageable for builders and beneficial for indoor air quality when combined with mechanical ventilation.

Exploring the Role of Airtightness for Achieving Carbon Neutrality in Canadian Residential Buildings: A Streamlined Life Cycle Assessment

This study delves into the relationship between airtightness levels and the entire life cycle carbon emissions of buildings across diverse Canadian climates. With the 2020 update of the National Energy Code of Canada for Buildings, whole-building airtightness testing was introduced as an option, prompting discussions on its mandatory nature. Using a net zero target, our assessment unfolds in two phases. Initially, we employ three-dimension (3D) modeling in Revit to replicate a typical Canadian detached house’s architectural features and material compositions. Subsequently, the model was imported into One Click life cycle assessment (LCA) to set parameters such as lifetime, gross interior area, and annual electricity consumption. Our analysis is bifurcated into assessing climatic conditions in Edmonton, Toronto, and Vancouver, alongside examining code-specified airtightness levels. We compared annual energy loss per unit area at varying airtightness levels accounting for the general deterioration of airtightness in new buildings during the pre-service phase to pinpoint the optimal airtightness value (ACH50) during the design stage. The subsequent phase evaluated increased carbon emissions from material replacement to meet this optimal airtightness condition and passive energy savings. Findings underscore that designing airtightness to an ACH50 value of 1.0 is the most energy-efficient. Comparative analysis reveals that achieving carbon neutrality solely through increased envelope airtightness and passive energy savings, is viable in Edmonton (18.4 years) owing to regional energy source disparities. In contrast, Toronto and Vancouver necessitate active energy-saving devices to attain carbon neutrality over the design lifetime.

Using trickle ventilators coupled to fan extractor to achieve a suitable airflow rate in an Australian apartment: A nodal network approach connected to a CFD approach

The level of airtightness is increasing in newly built Australian apartments. Due to the COVID-19 pandemic, restrictions have forced many people to work from home. An appropriate ventilation rate is needed to decrease virus transmission and provide occupants with a healthy environment. As occupants tend not to open windows, they need to be informed about the potential benefit of using trickle ventilators, in connection with exhaust systems, to ventilate their apartments. In 2022, a provision for lower rates of continuous ventilation (10 L.s−1 for the bathroom exhaust system and 12 L.s−1 for the kitchen exhaust system) was considered for inclusion in the National Construction Code of Australia. This provision was not adopted; however, this is still a valid reference for good practice. Based on this provision for continuous ventilation, our study aims to investigate the airflow velocity and the ventilation efficiency to remove the carbon dioxide (CO2) generated across winter and summer seasons in a Melbourne apartment occupied by two adults and a child over four hours.The study's objectives are 1) to connect two modelling approaches (Computational Fluid Dynamics and nodal networks), and 2) to investigate the potential benefits of using trickle ventilators across winter and summer seasons. The results show that wind conditions have limited effects (4% decrease in the extracted air flow rate) if the extraction network output is protected from the wind. Comparing winter and summer conditions, we found that indoor airflows differed, highly influenced by the temperature difference between outside and inside. We observed that the airflow patterns were more inclined to create “CO2 pockets” during winter, which could increase virus transmission due to ineffective ventilation in this area. However, in winter, ventilation performed better in reducing the CO2 concentration in the kitchen/living room area and the whole apartment than it did during summer.

Mitigating undercooling and overheating risk in existing desert schools under current and future climate using validated building simulation model

In Palestine and neighboring regions, buildings are constructed without insulation and mechanical heating and cooling systems, leading to significant thermal discomfort for occupants. To address this issue, the paper introduces a robust methodology that utilizes a validated building simulation model (BSM) created based on hourly indoor air temperature to assess indoor thermal comfort during winter and summer seasons under both current and future climates. This methodology is applied to an existing school built in 1990 in Jericho-Palestine, which has a hot desert climate. Classrooms rely on the thermal mass to increase the indoor temperature in the winter, and natural ventilation to reduce it in the summer. The effect of climate change on indoor thermal conditions is evaluated using typical warmer and colder future years based on the latest SSP5-8.5 scenario. The results showed that the calibrated and validated BSM achieved a highly accurate prediction of indoor air temperature compared to indoor air measured temperature. The validated BSM showed extreme cold for 880 h (91% of wintertime) and excessive heat for 90 h (19% of summertime) during school days. Passive winter measures, including high insulation and airtightness level, and using double glass windows, reduce undercooling to less than 40 h but increase overheating to 180 h. Passive summer measures, including night cooling and exterior shading, are necessary to reduce overheating to around 40 h. These measures are still effective in resisting the cold future years, but more creative passive summer measures and/or a mechanical cooling system are needed.

A Visualized Method of Airflow between Adjacent Zones inside a Multizone Building Based on Pressure Difference Frequency: Airflow Mapping

The airflow movement inside a multizone building has a significant impact on pollutant transfer, thermal comfort, and indoor air quality. However, there are difficulties in visualizing the airflow movement with existing methods. This study proposes a visualization method for evaluating airflows between adjacent internal zones inside a multizone building based on the analysis of pressure difference frequency. After the distribution of absolute pressure is measured and the wind pressures on the surfaces of the building are calculated, the variation of pressure differences between each couple of adjacent zones is analyzed for three levels: greater than 0 Pa, equal to 0 Pa, and less than 0 Pa (for any given zones selected as target zones). Finally, an airflow mapping is created for each floor using the visNetwork tool based on the R language. A target building was selected for applying the proposed method. The airflow mappings were derived from a detailed analysis of the pressure difference frequency between each couple of adjacent zones, presenting the variations of airflow direction and the dominant airflow during the measurement period in a visualized form. For example, the airflow direction from 1F_Z2 to 1F_Z3 is 92.0%. The spatial similarity in the variations of the airflow directions can also be observed on certain floors. The results of this experimental study show that the airflows between multiple zones can be easily identified without a complex building zone analysis. The variation in internal airflow direction between adjacent zones can be intuitively visualized, providing insight to the airtightness levels of building components. It is also observed that the airflow rates computed based on the airflow mappings can provide more guidance for the control of HVAC systems.

In-situ assessment of the thermal performance of earth masonry construction

The interest in traditional earth constructions has grown in Europe since a few years. This growing interest can be attributed to the fact that earth has among other qualities a good capacity for the hygrothermal regulation inside a building. This well-established ability of earth to store and manage heat and moisture has been extensively studied in the past at the material scale. However, the evaluation of the building envelop performance is rarely achieved in practice. This study presents an evaluation of the thermal performance of earth masonry construction based on in-situ measurements under real conditions of exposure. The construction consists of a single unoccupied room with habitable surface area of 12.9 m2 located in Canohès in the Southern France. Firstly, the airtightness of the envelop was quantified with the blower door test. The air permeability results indicated a very good level of airtightness. Then the thermal insulation of the envelop was measured according to the ISABELE method (In Situ Assessment of the Building EnveLope pErformances). The latter is a method developed by the CSTB to deduce the transmission heat transfer coefficient of the building with its uncertainty within short unoccupied period (few days). The results of the different ISABELE tests demonstrated that the total thermal insulation level of the tested envelop could be classified as good to average according to the scale of the building heat loss coefficient (Ubat) of the French Energy Performance Diagnosis. The results of the ISABELE tests were confirmed by the outcomes of a Coheating test conducted during a long period of 3 months. This study gives encouraging results on the application of the ISABELE method on earth masonry buildings to deduce the thermal performance of their envelope quickly, instead of a complete Coheating test which can be too long to apply in practice.

Analysis of the influence of pressure difference across building envelope on indoor particulate matter concentration

Outdoor PM2.5, penetrated by infiltration, has a continuous and important effect on indoor environments. To determine the infiltration rate, it is important to consider the airtightness level and pressure difference across an envelope. This study investigated the influence of pressure difference and airtightness on indoor PM2.5 in a residential building with natural ventilation. Field measurements were conducted in eight residential households. The indoor and outdoor PM2.5 concentrations and pressure differences across the envelope were measured simultaneously. The airtightness of each unit was determined via a blower door test. As a result, the indoor PM2.5 concentration exhibited a significant correlation with airtightness and envelope pressure difference. However, the correlation between the PM2.5 I/O ratio and the pressure difference was found to weaken as the airtightness decreased. This appears to be influenced more by other external factors in addition to pressure under loose airtightness conditions. Thus, the influence of the factors on the penetration of PM2.5 can vary depending on the airtightness of the envelope.

The Actual Efficacy of an Air Purifier at Different Outdoor PM2.5 Concentrations in Residential Houses with Different Airtightness.

It is important to control airborne particles in residential houses for protecting human health. Indoor particulate matter of <2.5 μm (PM2.5) can be effectively monitored and managed using an air purifier. In this study, the actual clean air delivery rates in residential houses (CADRActual) were acquired by comparing decay rates of fine particles with and without operations of the air purifier under actual conditions, following the standard CADR of an air purifier obtained in a closed test chamber. The measurements of CADRActual at different outdoor PM2.5 concentrations over a month in two residential houses revealed different airtightness levels, compared to the standardized clean air delivery rate of the air purifier (CADRAP). Air changes per hour at 50 Pa (ACH50) was 4.8 h−1 for “house A” (built in 2007) and 2.1 h−1 for “house B” (built in 2018). The CADR of the air purifier used in this study was 10.6 m3/min, while the averaged CADRActual at the “house A” was 7.2 m3/min (approximately 66% of the CADR of the air purifier) and 9.5 m3/min at “house B” (approximately 90% of the CADR of the air purifier). Under the outdoor PM2.5 concentrations of <35 μg/m3, the averaged CADRActual of house A and house B were 7.8 ± 0.3 and 9.7 ± 0.4 m3/min, respectively. However, under the outdoor PM2.5 concentrations of >35 μg/m3, the analogous averaged concentrations were 6.8 ± 0.6 and 9.6 ± 0.3 m3/min for houses A and B, respectively. The measured CADRActual agreed well with the theoretical estimates of CADRActual acquired by the mass balance equation using the infiltration rate of ACH50/20. We also estimated CADRActual/CADRAP for house C built in 2017, where the ACH50 was 1.8 h−1. Overall, this study demonstrated how CADRActual/CADRAP of an air purifier at residential houses can be predicted according to outdoor PM2.5 concentration and airtightness of the house. As shown, it can be closer to 1 at lower ACH50 houses and at lower outdoor PM2.5 concentrations.

Energy and emissions effects of airtightness for six non-residential buildings in Canada with comparison to contemporary limits and assumptions

Building air leakage is often a significant contributor to the energy consumption of a building and is difficult to characterize. Unlike the thermal performance of building envelope components, the high variability of airtightness of building assemblies and their interfaces makes air leakage of buildings difficult to predict. This publication describes the process and results for identifying leakage rates and locations within six non-residential buildings using airtightness testing, specifically six commercial buildings. Infrared (IR) scanning was used to visualize locations of air leakage in the building envelope. The energy and emissions effects from the measured performance were quantified and compared to the assumption in the relevant Canadian building code.The air leakage rates for all buildings tested in this work were less than the ASHRAE 90.1 standard limit of 2.0 L·s−1 m−2 @ 75 Pa, while three were less than the Air Barrier Association of America (ABAA)/United States Army Corps of Engineers (USACE) standard limit of 1.25 L·s−1 m−2 @ 75 Pa, and two were less than the National Energy Code of Canada for Buildings (NECB) assumption of 1.5 L·s−1 m−2 @ 75 Pa (a different area normalization is used for the NECB). The effects of airtightness on energy use intensity and annual operational emissions were quantified and found to be substantial and varied. The incremental energy use intensity ranged from a reduction of 47 kWh/m2ᐧyear to an addition of 64 kWh/m2ᐧyear.The most common location of leakage is between connections of building assemblies, especially the roof wall connection, and building components, particularly doorways, as well as at various envelope penetrations, such as for pipes and ventilation inlets/exhausts. The process of testing was documented and showed that the use of currently-available commercial equipment enables tests for typical small to medium-sized commercial/non-residential buildings to be completed efficiently. The results showed there is notable variation in airtightness levels between buildings and there are opportunities for improvement.

On Slowing Climate Change with Ecological, Thermo-Active Building Systems

In the early days of energy conservation(1980s) several countries took the need for energy efficiency seriously enough to sponsor some demonstration buildings. For instance, a US university design concept was built in Regina, Canada in1978. The Saskatchewan Energy Conservation house [1s]demonstrated a new, passive technology. It had super-insulated and airtight walls, large windows on the south facade, evacuated solar pipes for domestic water heating, and a heat recovery ventilator. Despite of all the technology demonstrated there, as Bomberg et al [2] explains, the passive measures were not accepted in the Canadian marketplace because the builders modified the heating system and thereby changed the air flow pattern in the house. The 1995, German passive house was accepted in marketplace because the built system could be duplicated as it was demonstrated. In this case, saving from the elimination of expensive boiler were used to improve the level of thermal insulation and air tightness. These developments led to acceptance of a few points from building science [2-4], namely: (1) any building is a system, (2) a design team should work together starting with the conceptual stage, (3) heat, air, and moisture flows are not separable, and their interactions must be recognized, (4) excellent air tightness and a high-level of thermal insulation are required in all climates.

A labelling strategy to define airtightness performance ranges of naturally ventilated dwellings: An application in southern Europe

Energy efficiency and indoor air quality are frequently-two conflicting objectives when establishing the air change rate (ACH) of a dwelling. In Europe, the northern countries have a clear focus on energy conservation, leading to an obvious awareness of the importance of airtightness, which translates into a high level of regulation and implementation. Meanwhile, the southern counterparts experience a more complex challenge by having predominantly passive ventilation strategies and milder climates, which often results in a more permissive approach.This work proposes an innovative labelling methodology to classify the performance of naturally ventilated dwellings. A representative sample of a southern European national built stock is used in a stochastic process to create a pool of 43,200 unique dwellings. The simulation period refers to a month of the typical heating season in the southern European mild conditions. The results test the labelling methodology. With feature selection, ACH limits, and a labelling strategy, dwellings classify according to their ability to provide adequate ACHs.The terrain was the best splitter of the dataset from the applied categorical variables. Regarding continuous variables, the airtightness was the one explaining most of the variability of the outputted ACHs, followed by the floor area. From the best performing dwellings labelled as compliant (Com), the average airtightness level was 5.3 h−1, with 4.9 h−1 and 5.8 h−1 in rural and urban locations.

Simulation of modern passive stack ventilation in a retrofitted Nordic apartment building

Some heritage or protected residential buildings in Nordic conditions require retrofit; however, having limited or no access to the reconstruction of the ventilation system; thus, the native natural ventilation system must be preserved. Some retrofitted buildings are then equipped with modern passive stack ventilation systems implemented with self-regulated supply inlets. Although natural ventilation strongly depends on climate conditions, creating challenges in the design phase as the indoor air quality can not be guaranteed. In this study, such a building was modelled, and a novel self-regulated inlet component was created and applied to the simulation model of the multi-storey residential building with natural ventilation in the Nordic conditions. This IDA ICE model is implemented with a self-regulated inlet model with outdoor temperature control and simulates the yearly performance of a ventilation system, considering the effect of outdoor conditions, such as air temperature and wind direction. The self-regulated device is represented as a one-direction opening based on power-law with variable internal airflow resistance, calculated based on the outdoor simulation temperature. Several case scenarios of the multi-storey residential building with passive stack and windows opening ventilation were created for the analysis. The cases present possible maintenance issues, such as inlet device dirty filter and passive stack ducts, structural differences, such as envelope airtightness level and occupant behaviour, such as internal apartment doors and windows operation. The resulting CO2 concentration, indoor air temperature and air change rate were analysed and compared against indoor air standards. Overall, the building model simulation results coincide well with studies in comparable conditions; the novel self-regulated inlet device was simulated according to the manufacturer data. The resulting simulation model could be used to assess the performance of modern passive stack ventilation under different climatic conditions.

The Required Amount of Ventilation Air for the Classroom and the Possibility of Air Infiltration through the Windows

The majority of education buildings in Poland are equipped with natural (gravity) ventilation, where the air inflow depends on the level of window airtightness. A complete statistical urban population of 50 school buildings in Czestochowa have been examined. The main issue to be clarified is the answer to the following questions: Is it theoretically possible to supply enough air to meet the ventilation requirements with gravity ventilation? What is the airtightness of the windows at which it will be possible? The average technical conditions of windows in the analysed buildings were bad. However, only in the case in which high external air leakage coefficient a = 7.0 m3/(h m daPa2/3) (q100KL = 32.4912 m3/(h m) is the amount of air passing through the leaks similar to the quantitative ventilation requirements for classrooms. The quantity of air flowing from the outside through modernized windows that meet the technical requirements (a = 0.6 to 1.0 m3/(m h daPa2/3)) covers on average only about 12% and about 21% of the ventilation needs. Without installing additional vents in the rooms, or better yet, installing mechanical ventilation with heat recovery, meeting the ventilation norm requirements will be impossible.

Evaluating Insulation, Glazing and Airtightness Options for Passivhaus EnerPHit Retrofitting of a Dwelling in China’s Hot Summer–Cold Winter Climate Region

Passivhaus EnerPHit is a rigorous retrofit energy standard for buildings, based on high thermal insulation and airtightness levels, which aims to significantly reduce building energy consumption during operation. However, extra retrofit materials are required to achieve this standard, which raises a contradiction between how to balance the environmental impacts of the retrofitting material inputs and extremely low energy consumption after retrofit. This motivated the analysis in this paper, which aimed to evaluate the possibilities of reducing the required retrofitting material inputs when trying to achieve the EnerPHit energy standard using a typical suburban dwelling in China’s hot summer–cold winter climate region as a case study. Firstly, how the insulation performance of each envelope component affected the building’s energy consumption was analysed. Based on this, sensitivity simulations of combinations of different insulation levels with different fabric components were investigated under four scenarios of insulation levels, airtightness and glazing choice. The final proposed retrofitting plans achieved the EnerPHit standard with insulation materials’ savings between 18% to 58% compared to a baseline retrofit plan, and this led, in turn, to 3.9 to 12.6 tonnes of carbon reductions. Moreover, an energy-saving of 87% in heating and 70% in cooling was achieved compared with the pre-retrofit dwelling.

ANALYSIS OF THE AIRTIGHTNESS MEASUREMENT IN SINGLE OR DOUBLE APARTMENT HOUSE

The mandatory energy performance certification of new buildings or buildings for sale has been introduced in all Member States in order to achieve European Union’s energy efficiency goals. The certification of buildings sets mandatory requirements for higher energy efficiency buildings’ level of airtightness. However, a bigger problem lies in existing older residential buildings, which are energy inefficient and do not require certification. The unused potential for energy savings observed here is related to the airtightness of single and double apartment residential buildings and energy efficiency related to airtightness of them. Therefore, this work analyses the airtightness of energy class D and lower buildings based on actual airtightness measurements and evaluates the possible energy saving potential associated with the application of airtightness measures based on the example of one inefficient single apartment building. The results show that increase of the airtightness in such buildings to 3 h–1 enables to reduce the energy costs related to the airtightness in Lithuania over a period of 10 years by 0.17 TWh per year.

Can commercial buildings cope with Australian bushfires? An IAQ analysis

The Australian 2019/20 summer witnessed an extraordinary bushfire season characterised by unprecedented duration, geographical reach and impact. The aftermath of the bushfires includes increased health-related implications on people due to short and long exposure to poor air quality. The current advice from the Australian authorities in such events is to remain indoors, as it was assumed indoor air quality (IAQ) is healthy. This paper examined that assumption and presents the case study of an office building in Canberra subjected to the 2019/20 bushfires, responding to the need of understanding the ability of air-conditioning buildings to cope with such unprecedented and extreme weather events. Measured data for indoor concentration of CO₂, PM₁₀ and PM_2.5 recorded a prolonged period of concerning levels, as well as extreme concentration peaks. This poses a significant risk to the occupants’ health. The values showed peaks up to 12 times higher for PM₁₀ and 24 times higher for PM_2.5 than the recommended critical thresholds. The infiltration factor and protection performance analysis suggest that old filtering systems and low airtightness levels are not optimal in protecting the indoor environment from outdoor air pollutants. <em><strong>Practice relevance</strong></em> Results show that the concentration of the outdoor pollutant significantly exceeded thresholds for a prolonged time, posing a health risk to the population. The case study presented has been partially able to protect its occupants thanks to the heating, ventilation and air-conditioning (HVAC) response, but this brings up the concern about all those spaces where mechanical ventilation may not be installed or have the same filtering system. Evidence provided here calls for an urgent update of the protection agenda to account for extreme weather events with regard to the diverse indoor built environments, because relying on the mechanical ventilation system is no more sufficient to provide healthy and safe environments.

Is green certification the solution to substandard indoor air quality (humidity)? A case study of old, new and green-certified dwellings

ABSTRACT New Zealand is hamstrung by a housing crisis. Although the discourse primarily focuses on housing affordability and homelessness, there is a more pervasive problem afflicting New Zealanders: that New Zealand homes are substandard, being cold, damp and difficult to heat. This article reviews the moisture levels of three categories of housing (older vintage, newly constructed and newly constructed green certified) in Auckland, New Zealand, to determine whether the pervasive issue of high internal humidity in housing can be successfully rectified through using a green building certification. The results show that newly constructed 6-Homestar dwellings are in the optimal relative humidity range mean 14 per cent of time in contrast to 17 per cent for new code-compliant dwellings (and six per cent for older vintage dwellings) in the damp winter months of June through August. This research documents that a particular green certification – 6-Homestar – may not deliver suitable humidity control, and that alternative certifications that stipulate airtightness levels and require active ventilation – such as Passive House – could be considered by policy makers interested in delivering low-carbon, warm, dry houses in New Zealand.

Watertightness performance of face-sealed versus drained window-wall interfaces

Several research studies have identified window-wall interfaces as one of the major sources of water ingress through building envelopes. Window-wall interfaces can either be sealed by means of face-sealed or drained sealing systems. In general, it is assumed that drained window-wall interfaces show an improved rainwater resistance compared to face-sealed interfaces. However, only a limited number of studies can be found in literature evaluating the watertightness performance of both face-sealed and drained window-wall interfaces. The objective of this paper is to evaluate the performance of both face-sealed and drained sealing methods and to identify the primary factors affecting the water resistance of window-wall interfaces.Various combinations of exterior seal, drainage layer, air barrier, airtightness level, installation method and wall assemblies were assessed by means of 5 face-sealed test specimens and 9 drained specimens. Both static and cyclic tests were performed. It was found that both tests showed corresponding results with regard to the pressure threshold value for water ingress. The results in this study also indicated that the airtightness of the interfaces and the presence of a separate air barrier at the interior side of the interface affected the watertightness performance to a great extent. The findings showed that it is very difficult to obtain water resistant face-sealed window-wall interfaces, even in lab conditions. It is therefore recommended to always provide drainage possibilities behind the exterior seal or cladding.

Quantifying airtightness in Brazilian residential buildings with focus on its contribution to thermal comfort

ABSTRACT Airtightness refers to the amount of air leakage through a building’s envelope. This uncontrolled exchange of air between inside and outside, either infiltration or exfiltration, may lead to thermal discomfort. Nevertheless, little or no attention has been given to airtightness in some countries including Brazil. In Brazil, a range of different strategies are suitable to achieve thermal comfort depending on the several climatic regions. In those regions where winter conditions are noticeable, such as in São Paulo, airtightness is a key parameter, but it has been historically overlooked. In this work, the authors deployed the innovative Pulse test methodology to determine airtightness levels for the first time in Brazil, in the city of São Paulo. Three representative multifamily residential buildings dating from the 1970s, 1980s and 2000s were measured, and the results’ values widely ranged from 1 to 5.7 h−1, at 4 Pa. Next, dynamic building simulations were conducted using measured and representative airtightness values (converted to infiltration) to understand the contribution of this variable on the thermal comfort. The results suggested that up to 9% improvement in the thermal comfort levels could be achieved by adopting 1 h−1 as maximum infiltration, and up to 14% by adopting 0.5 h−1.

Airtightness of sealed building joints: Comparison of performance before and after artificial ageing

Airtightness is considered an important factor on all levels of the building envelope, i.e. overall building envelope, on a component level and on a material level. Airtightness of the building envelope is a defining factor to achieve energy efficient and durable buildings, i.e. reduced risk of condensation and water infiltration through the building envelope, reduced risk of cold draughts and it improves the correct functioning of the HVAC-system. Over the past decades the amount of airtightness tests for newly built buildings in Belgium has significantly increased. However, the measured airtightness level of the tested buildings from 2006 to 2016 did not significantly change. This implies that there is still a lack of knowledge to achieve airtight building details, both on a design level and on the implementation of the building details. However, literature concerning airtightness of sealed building joints is very limited. In this study, the airtightness performance of different materials to seal building joints was experimentally assessed. In general, a good airtightness was achieved for all tested materials in case they were perfectly installed. However, the performance of the sealing materials was very sensitive to faulty workmanship and primarily depended on the quality of implementation, in particular for the tapes, silicone based materials and foam sealing strips. The performance of the liquid applied coating primarily depended on the characteristics of the materials and the application method was determining for the performance of the polyurethane foams.