Internal Doors Research Articles

Testing the system: infant ‘abduction’

Infant abductions from hospital are rare events but make headline news. A US study examined 247 infant abductions between 1983–2006 and found nearly half were abducted from healthcare settings [1]. Abduction risk reduction strategies are also considered during the Care Quality Commission’s inspection of each maternity unit [2]. The baby tagging system was updated in our hospital in April 2020, training undertaken and subsequently reinforced with e-learning. In our hospital, many families have safeguarding concerns. These are considered the highest potential risk for infant abduction so it is essential the system and processes provide protection. The aim of this simulation was to test the processes currently in place for a tagged baby abduction from an inpatient ward to highlight good practices and identify system failures. An activated tag was assigned to a manikin on the transitional care unit. The manikin was removed, in a carrier bag, by a faculty member (‘the abductor’) tailgating a leaving staff member thus preventing the ward doors from automatically locking when the tag is near the sensor. The ‘abductor’ took the lift to the ground floor and walked out of the main entrance within three minutes. Faculty members were placed in transitional care (TC), the main entrance, and another tracking the tag’s location. A timeline of events was recorded and analysed. Simulation participants were debriefed, including staff directly involved, parents on TC, front of house staff, and senior managers. It was evident from the debriefing that this caused significant distress to some staff members who felt helpless and uncertain when faced with this scenario. It highlighted how quick and easy it is to leave the hospital with a baby. Important human factors were identified including discrepancies between emergency call requests and responses, and poor knowledge about the abduction of baby policy. System problems were found: hospital ‘lockdown’ locked internal doors preventing responder actions but not all external doors; and the tagging system did not respond as expected – locking the doors to the ward and an inaccurate final tag location. Multiple deficiencies in the system were found so an action plan has subsequently commenced. New external doors have been added to automatic lockdown and a new main entrance door system proposed. Tagging engineers are addressing the automatic locking of internal doors and tag location, switchboard calls are to be standardised, and the standard operating procedure is being reviewed and recirculated. 1. Burgess AW, Carr KE, Nahirny C, Rabun JB Jr. Nonfamily infant abductions, 1983–2006. Am J Nurs. 2008 Sep;108(9):32–8. doi: 10.1097/01.NAJ.0000334972.82359.58. PMID: 18756155. 2. Care Quality Commission NHS IH Maternity core service framework v7 (2018)

Environmental and socio-psychological drivers of building users’ behaviours: a case study of tertiary institutional offices in Auckland

PurposeBetter identification of comfort preferences and occupant behaviour drivers is expected to improve buildings’ user-centred designs and energy operations. To understand the underline drivers of occupant behaviours in office buildings, this study aims to evaluate the inter-relationships among occupant energy behaviours, indoor environmental quality satisfaction, user control and social-psychological factors influencing occupant behaviours in New Zealand offices.Design/methodology/approachUsing an occupant perception survey, this study identifies the occupant behaviour patterns based on multi-domain comfort preferences. A case study was conducted in five office spaces of a university in Auckland, New Zealand. Data were collected from 52 occupants and analysed using descriptive and binary logistic regression analysis. Indoor environmental quality, user control, motivational, opportunity and ability factors were the independent variables considered. A model to predict the behaviours using environmental, building and social-psychological aspects was developed.FindingsThe results showed that the primary sources of indoor environmental quality discomfort were related to thermal and air quality, while occupants’ indoor environmental quality satisfaction correlated with their comfort preferences. The outcomes emphasise how the connection between building systems and occupants’ comfort preferences affect the choice of occupant behaviours in offices. Also, the primary occupant behaviours were drinking hot and cold beverages, opening/closing windows and internal doors and adjusting clothing. The binary logistic regression analysis showed that occupants’ perceived user control satisfaction is the main driver for increasing window actions. No other independent variable showed a statistically significant association with other behaviours.Originality/valueThis study adopted a novel approach to assess the combined effects of comfort preferences, occupant energy behaviours and various environmental, building and socio-psychological factors for modelling energy-saving behaviours in office buildings.

Role of ventilation on the transmission of viruses in buildings, from a single zone to a multizone approach.

In a virus pandemic context, buildings ventilation has been recognized as a solution for preventing transmission of the virus in aerosolized form. The impact of the widespread recommendation of window opening and sealing door on ventilation circuits needs to be considered with a multizone approach. We modeled the airflow distribution in a building where people are isolating in a pandemic context, including one infected person. We analyzed the impact of opening the window and sealing the door in the quarantine room on exposures and probability of infection for occupants of the flat and of adjacent flats. In order to study the sensitivity of the results, we tested three ventilation systems: balanced, exhaust‐only, and humidity‐based demand‐controlled, and several window‐ and door‐opening strategies. When the door of the quarantine room is sealed, we observe that opening the window in the quarantine room always results in increased exposure and probability of infection for at least one other occupant, including in neighbors' apartments. When all internal doors are opened, we observe moderate impacts, with rather an increase of exposure of the occupants of the same apartments and of their probability of infection, and a decrease for the occupants located in other apartments. Based on the analysis on the airflows distribution in this case study, we conclude that sealing the internal door has more influence than opening the window of the quarantine room, whatever the ventilation system. We observe that this widespread recommendation to open the window of a quarantine room and to seal the door is based on the consideration of a single zone model. We illustrate the importance of moving from such a single zone approach to a multizone approach for quantifying ventilation and airing impacts in multizone buildings as residences in order to prevent epidemics of viruses such as SARS‐CoV‐2. It highlights the need of air leakage databases.

Making homes more accessible for people with mobility impairment: A lived experience perspective

AbstractPeople with mobility impairment have the right to live in accessible housing that meets their needs. Although the Australian National Construction Code for residential housing will be amended to include minimum accessibility standards in September 2022, some states have chosen not to adopt these standards (New South Wales, Western Australia and South Australia). The inclusion of people with lived experience in decisions surrounding accessible housing design is lacking. This study sought the perspective of people with mobility impairment on the most important modifications they would make to the design of their own homes, and the homes of their friends and family, to make them more accessible. An online survey was completed from February to March 2021 by 145 people living in Australia including 112 people with mobility impairment, and 33 family members. Results indicated that 71 per cent of the participants were living in housing that did not fully meet their accessibility needs. Descriptive qualitative analyses demonstrated that commonly reported modifications included a step‐free entrance, wider internal doors and corridors, and level access throughout the home. These modifications would promote social inclusion, functioning, independence and overall quality of life. These results have policy implications for the implementation of accessibility standards in the National Construction Code.

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.

Study of Homogeneous Chipboard Manufacturing u sing Betung Bamboo (Dendrocalamus Asper) Mixed with Polyethylene Addictive

Bamboo is an evergreen plant native to Asia and America that grows at every altitude, even in unideal climate conditions. Betung bamboo or its scientific name Dendrocalamus Asper is one of the bamboo species that are easily found in peninsular Malaysia. This study examined the characteristics of Betung bamboo and its potential to manufacture chipboard. Several tests were conducted, namely modulus of elastic (MOE), modulus of rupture (MOR), thickness swelling (TS), and water absorption (WA) to evaluate the potential of Betung bamboo as the primary material in the manufacture of chipboard mixed with polyethylene as additive are the parameters considered. This study found that the composition of 70% bamboo and 30% polyethylene was produced optimum chipboard which met BS EN standards (British and European Standard). It was also found that the MOE and MOR values of the resulting chipboard exceeded the medium density board standards. For WA and TS values, the chipboard achieved the standard requirements. Thus, this study concludes that chipboard made of Betung bamboo with the addition of polyethylene is suitable to be applied for internal and external doors, and internal paneling for any commercial or domestic building and furniture.

MODELING OF BUILDINGS

The selection of building materials from various available alternatives is a critical process affected by many complicated factors. Every single element in a building has a specific function to perform. This necessitates a proper selection of material from the various available alternatives, which generally differ in their quality, performance, and cost. To make the most practical choice, the owner wants the building's function to perform with maximum quality at the minimum possible cost, and this is the principle of value engineering. Therefore, a determination has been made to identify the criteria impacting selecting each element and how close it is to achieving the project's goal. Each alternative has been evaluated, and its quality, and cost scores have been calculated. Implementing a value engineering process is challenging, and it needs much effort and many brainstorming sessions to be achieved. Therefore, this study has proposed a framework to automate the value engineering process and integrate it into selecting building materials. Moreover, this process was accelerated and facilitated by using innovative computer technology such as building information modeling (BIM) that has been widely used in the architecture, engineering, and construction industry. The scientific paper touched on determining the evaluation of the elements of choosing the doors and determining the criteria affecting their quality by conducting a field survey with specialized engineers in the Kingdom of Saudi Arabia to know the factors affecting the selection of doors. The scientific paper also reviewed the case study of a hospital buildingwhere the elements of the building's internal doors are chosen from among eight alternatives using the proposed evaluation processes. And then, chose the building information model as a database that facilitates information entry and selected from the available alternatives. The results were shown automatically and gave a summary of them. The research results showed the six most important criteria affecting the process of selecting interior doors for buildings: fire resistance, acoustic insulation, humidity resistance, aesthetic, durability, and maintenance. Based on this study, the best alternative for interior doors to buildings will be chosen from among the eight available alternatives. This methodology will make it easier for the decision-maker to choose the appropriate section according to the previous criteria.

Technical Solutions for Means of Rail Transport in Improving Accessibility for People with Disabilities and with Reduced Mobility

The article includes an analysis involving the requirements for the adaptation of rolling stock for use by people with movement dysfunction. The requirements including construction and dimensions have been summarized and detailed conditions necessary to ensure the assumed level of travel comfort for people with reduced mobility with real examples of solutions used in currently operated railway vehicles. The focus was on the requirements set out in Regulation No 1300/2014 regarding technical design and construction solutions for adapting railways to the transport of disabled people, TSI PRM. Based on the collected material, an analysis of the compliance of the actual state with the theoretical one, included in the standard, was carried out. Elements designed and manufactured in a manner consistent with the recommendations contained in the standard, as well as those that require a re-analysis of rolling stock constructors, repair or necessary changes are indicated. The components analyzed included, among others, seating positions, movement zone - including internal and external doors, toilets or platforms enabling access to the interior of the vehicle The opinion of disabled people using rail transport was also included by conducting a survey and performing analysis and then interpretation of the data obtained. Basing on this analysis, solutions that will increase the comfort of travelling for people with disabilities have been proposed.

Improvement Of The Production Process With The Use Of Selected Kpis

Abstract Faced with ever-increasing customer demands and global competition, companies are forced to look for production reserves, increase efficiency and productivity. Hence, the need to monitor the use of the machine park has arisen, making it possible to identify waste and production reserves in the implemented technological processes. The aim of the article is to evaluate the effectiveness of the production line of internal frame doors and to analyze the correctness of the use of selected key indicators of the production process effectiveness. This article proposes a response to the problems formulated in manufacturing companies, including practical aspects of the use of specific measures to assess the effectiveness of the use of technical infrastructure. The solutions presented in the article can be used in practice for improvements in production units.

Graphic designed bedroom doors to support dementia wandering in residential care homes: Innovative practice.

Dementia-friendly designs are important in residential care homes but an aspect that remains neglected is the potential role of door designs in promoting wayfinding. A pilot project in NSW, Australia, tested the effects of unique room door designs for a small group of individuals living with dementia in a residential care home. Internal doors were transformed using a giant adhesive poster created by a commercial graphic designer. The poster replicated the look of traditional front doors, including a range of bright bold colours and architectural features, such as brass doorknockers, letterboxes and door guards. The Revised Algase Wandering Scale (RAWS) was used to identify the effects of introducing the doors on persistent walking, eloping behaviours and spatial disorientation. A total of nine individuals living with dementia participated in the project. The post-intervention data demonstrated that there was a reduction in persistent walking, eloping behaviours and spatial disorientation. In addition, ongoing anecdotal evidence found that individuals continued to seek out others to showcase their unique door.

Internal door closing habits in domestic premises: Results of a survey and the potential implications on fire safety

It is generally accepted that keeping doors closed provides a means of protection by limiting smoke and fire spread. In the design of domestic buildings, it is therefore often assumed that occupants maintain a habit of keeping internal doors closed. The paper presents the results of an online survey to determine respondents’ internal door closing habits for their domestic premises. This attracted 304 responses (250 of which were from the UK) and was then followed by a more detailed survey, attracting 26 replies, to elaborate on respondents’ rationale behind their habits. The findings indicate that the overall probability that a kitchen, living room and bedroom door are closed while occupants are sleeping is 46%, 45% and 60%, respectively. It was found that the type of property, and whether respondents have children or pets, all have an influence on door closing habits. Respondents who lived in apartments were found to be up to 27% less likely to close kitchen or living room doors but more likely to close bedroom doors before going to sleep (+19%). In all instances, respondents with pets were typically more likely to keep doors open (ranging from 0% difference to +16%). However, when considering door closing behaviours for pet owners independent of the property type, it was found there was no statistically significant difference for bedroom door closing habits when sleeping. The analyses in this paper ultimately point towards the potential for daily household activities to take priority over the safety benefits which internal doors can provide.

The Door to Peace

Czeslaw Milosz’s poem Późna dojrzałość describes the experience of spiritual breakthrough. His past time hero feels incomplete. Full--time starts for him at the time of “awakening”. However, deep experience of “me” leads eventually beyond ego – towards the relations with others. The protagonist recognizes both a personal value of himself and of the others. It is the dignity of a “child of the King”, it has its source not so much in axiology, as in the ontology. The described spiritual breakthrough does not solve world’s problems, but introduces a new perspective of their understanding. It allows – thanks to a deep experience of hope – to anticipate the future harmony. Internal doors allow the hero to look into something which will become complete at the end of time, yet it now exists in the form of announcement hidden in the structure of reality.

Managing embodied carbon in buildings: a Pareto approach

PurposeThe purpose of this paper is to identify the carbon intensive building elements or “carbon hotspots” of office buildings in order to maximise the carbon reduction potential during design stages.Design/methodology/approachEmbodied carbon (EC) estimates of 28 office buildings in the UK were obtained and carbon hotspots of the sample (in accordance with the new rules of measurement (NRM) element classification) were identified using the 80:20 Pareto principle.FindingsFrame, substructure, external walls, services and upper floors were identified as carbon hotspots of the selected sample. However, findings do not support the 80:20 ratio in this case but propose a ratio of 80:36. Stairs, internal walls and partitions, internal doors, wall finishes, ceiling finishes and fittings and furnishings were identified as carbon insignificant elements that have a lower EC reduction potential compared to the rest.Research limitations/implicationsThe findings are applicable to office buildings in the UK but the methodology is adaptable to different types of buildings in other countries.Originality/valueFindings unveil carbon intensive and carbon insignificant building elements of typical office buildings in the UK. This informs designers of the elements that could yield the highest potential EC savings via effective design choices. In addition, a logical design timeline is proposed for building elements based on their element hotspot category and design sequence to assist design decision making.

Carbon and cost critical elements: a comparative analysis of two office buildings

PurposeThe purpose of this paper is to identify and compare cost and carbon critical elements of two office buildings, and to help achieve an optimum balance between the capital cost (CC) and embodied carbon (EC) of buildings.Design/methodology/approachCase study approach was employed to study cost and carbon critical elements of two office buildings as it allows an in-depth and holistic investigation. Elemental estimates of CC and EC were prepared from BoQs of the two buildings by obtaining rates from the UK Building Blackbook. Pareto principle (80:20 rule) was used to identify carbon and cost critical elements of the two buildings, and the significance hierarchies of building elements were compared.FindingsSubstructure, frame and services were identified as both carbon and cost critical elements responsible for more than 70 per cent of the total CC and EC of both buildings. Stairs and ramps, internal doors and fittings, furnishings and equipment were identified to be the least carbon- and cost-significant elements contributing less than 2 per cent of total CC and EC in both buildings. The hierarchy of cost and carbon significance varies between buildings due to the difference in the specification and design.Originality/valueThe increasing significance of dual currency (cost and carbon) demands cost and carbon management during the early stages of projects. Hence, this paper suggests that focusing on carbon and cost-intensive building elements is a way forward to keep both cost and carbon under control during the early stages of projects.

At Home with Doors: Practising Architectural Elements in Yes, These Eyes Are the Windows and Between 13 and 15 Steps

This article investigates artistic responses to doors in Yes, These Eyes are the Windows (2014), an installation, and Between 13 and 15 Steps (2015), a practical workshop ‘laboratory’, which both took place in houses. It argues that doors provide critical points of focus for the practice and study of artistic engagement with place. In so doing, it responds to recent interest by architects and theorists in doors as architectural ‘elements’, notably Von Meiss, who defines doors as ‘site’, ‘object’ and ‘threshold’ (Koolhaas 2014, Von Meiss 2013). The article considers how artists reveal and reflect on the significance of practising doors as a means of opening up understandings of place. The article proposes that, by addressing ways in which artists attend to elements of architecture, in installation and performance, we will better understand the significance of such elements, separately and in combination, on our sense and practices of place. It addresses performances of external and internal doors in Yes, These Eyes are the Windows and Between 13 and 15 Steps. In both works, artists articulated, commented upon, reimagined and reshaped the ways in which specific doors determine relationships between people and place in a house, and between life in a house and in its local context. The article invites further exploration of doors in installation and performance, as part of a broader investigation of the significance of practising architectural elements in artistic engagements with place.

Investigation of PCM as retrofitting option to enhance occupant thermal comfort in a modern residential building

This study investigated the feasibility of PCM as a retrofitting option to reduce the zone air temperature and improve occupant thermal comfort under free running condition in an existing house in Melbourne, Australia. Both the experimental and numerical approach were applied in this study. In the experimental study, PCM was installed in the ceiling of one of the rooms and indoor air temperatures of two rooms (one with PCM and the other without PCM) were recorded. A simulation model was developed using building simulation software EnergyPlus and validated using the recorded experimental temperature data. The results showed up to 1.1°C reduction in BED 2 indoor air temperature during daytime and 34% reduction in thermal discomfort hours through the passive installation of PCM on the ceilings. Several simulations including different user behaviour scenario (windows and internal door operations) were carried out to identify the influence of user behaviour on the effectiveness of PCM. It was observed that integration of PCM is more effective in reducing thermal discomfort hours if windows are kept open at night for night purging and the internal doors are remained closed at all time to prohibit any mixing with surrounding zones without PCM. Further improvement in PCM effectiveness was observed when similar amount of PCM was spread in the ceiling and walls.

Diurnal and seasonal variation in air exchange rates and interzonal airflows measured by active and passive tracer gas in homes

Outdoor air delivery to buildings is an important parameter in the assessment of pollutant exposure indoors. Detailed and well controlled measurements of air exchange rates (AER) and interzonal airflows in residential environment are scarce. We measured the outdoor AERs in up to six rooms in five dwellings across four seasons using active tracer gas. Night time AERs were also estimated in the bedrooms based on occupant-generated CO2. Passive tracer gas measurements were performed for comparison. AERs changed frequently during the day. Differences in outdoor AERs were observed between individual rooms. Window opening behavior had a strong influence on AERs, which were highest during occupied daytime periods, lowest in the night; highest in the summer, lowest in the winter. Significant differences were found between AERs measured by the different techniques. The median nighttime AER in all bedrooms across the four seasons was 0.49 h−1 with the active tracer gas technique and 1.20 h−1 with the CO2 method. The average winter AER in the five homes with the passive tracer (0.63 h−1) differed substantially from the corresponding AER measured with the active tracer gas (0.25 h−1). Additionally, we studied the pollutant distribution from one room (source room) and interzonal airflows across the dwellings. The air within a given floor was well mixed, with the average tracer gas concentration in the non-source rooms reaching approximately 70% of the source room concentration. There was less air movement between different floors. The position of the internal doors had a strong influence on the air movement.

Short-term dynamics of indoor and outdoor endotoxin exposure: Case of Santiago, Chile, 2012

Indoor and outdoor endotoxin in PM2.5 was measured for the very first time in Santiago, Chile, in spring 2012. Average endotoxin concentrations were 0.099 and 0.094 [EU/m3] for indoor (N=44) and outdoor (N=41) samples, respectively; the indoor–outdoor correlation (log-transformed concentrations) was low: R=−0.06, 95% CI: (−0.35 to 0.24), likely owing to outdoor spatial variability.A linear regression model explained 68% of variability in outdoor endotoxins, using as predictors elemental carbon (a proxy of traffic emissions), chlorine (a tracer of marine air masses reaching the city) and relative humidity (a modulator of surface emissions of dust, vegetation and garbage debris). In this study, for the first time a potential source contribution function (PSCF) was applied to outdoor endotoxin measurements. Wind trajectory analysis identified upwind agricultural sources as contributors to the short-term, outdoor endotoxin variability. Our results confirm an association between combustion particles from traffic and outdoor endotoxin concentrations.For indoor endotoxins, a predictive model was developed but it only explained 44% of endotoxin variability; the significant predictors were tracers of indoor PM2.5 dust (Si, Ca), number of external windows and number of hours with internal doors open. Results suggest that short-term indoor endotoxin variability may be driven by household dust/garbage production and handling. This would explain the modest predictive performance of published models that use answers to household surveys as predictors. One feasible alternative is to increase the sampling period so that household features would arise as significant predictors of long-term airborne endotoxin levels.

CO2 concentration in day care centres is related to wheezing in attending children

Poor ventilation at day care centres (DCCs) was already reported, although its effects on attending children are not clear. This study aimed to evaluate the association between wheezing in children and indoor CO2 (a ventilation surrogate marker) in DCC and to identify behaviours and building characteristics potentially related to CO2. In phase I, 45 DCCs from Lisbon and Oporto (Portugal) were selected through a proportional stratified random sampling. In phase II, 3months later, 19 DCCs were further reassessed after cluster analysis for the greatest difference comparison. In both phases, children's respiratory health was assessed by ISAAC-derived questionnaires. Indoor CO2 concentrations and building characteristics of the DCC were evaluated in both phases, using complementary methods. Mixed effect models were used to analyze the data. In phase I, which included 3,186 children (mean age 3.1 ± 1.5years), indoor CO2 concentration in the DCC rooms was associated with reported wheezing in the past 12months (27.5%) (adjusted odds ratio (OR) for each increase of 200ppm 1.04, 95% CI 1:01 to 1:07). In phase II, the association in the subsample of 1,196 children seen in 19 out of the initial 45 DCCs was not significant (adjusted OR 1.02, 95% CI 0.96 to 1.08). Indoor CO2 concentration was inversely associated with the practices of opening windows and internal doors and with higher wind velocity. A positive trend was observed between CO2 and prevalence of reported asthma (4.7%). Improved ventilation is needed to achieve a healthier indoor environment in DCC.

A simulation study of the changes in PM2.5 concentrations due to interzonal airflow variations caused by internal door opening patterns

Short-term variations in interzonal airflows can cause significant fluctuations in gaseous or particulate matter concentrations in indoor environments and therefore, interzonal airflow variations need careful consideration when modelling indoor pollutant concentrations. This study investigates the potential accuracy of modelling interzonal airflow variations and assesses the effect of interzonal airflow variations on indoor pollutant concentrations. A variable interzonal airflow is compared with a time-weighted average interzonal airflow, and the differences in the resulting estimates of indoor pollutant concentrations are analysed. Interzonal airflow variations were simulated by the opening/closing of internal doors for periods of 1, 2, 5, 10, 15 and 30 min. Based on experimental comparison, it can be concluded that the modelling approach used, accurately predicts PM2.5 concentrations for interzonal airflow variations for durations of 10 min or greater, with increasing accuracy for longer durations. The simulations demonstrate that both the time of occurrence and duration of the interzonal airflow variations are critical in determining indoor concentrations, and indicating that a time-weighted average interzonal airflow is not a suitable substitute for modelling interzonal airflow variations, as it under-predicts mean PM2.5 concentrations by up to 28%.