Hector Altamirano - Academia.edu (original) (raw)

Papers by Hector Altamirano

The Implications of Future Wind-Driven Rain Exposure on the Hygrothermal Performance of Internally Insulated Solid Walls in London, 2021

With approximately 40% of the London building stock built before 1919, internal wall insulation (... more With approximately 40% of the London building stock built before 1919, internal wall insulation (IWI) is one of the likely measures for deep retrofit to meet carbon emissions targets. However, IWI can lead to moisture accumulation and associated unintended consequences, especially in walls highly exposed to wind-driven rain (WDR). Climate change is predicted to exacerbate WDR exposure. This paper presents a comparative analysis between the hygrothermal performance of IWI under current and far future (2080) climates. Historic weather station data and UKCP18 climate projections were used to develop weather files for simulating current and future climate, respectively. Hygrothermal simulations were performed using DELPHIN. Assemblies include calcium silicate, phenolic foam, and wood fibre systems. Future climate predictions are associated with a rise of interstitial relative humidity, leading to patterns more favourable to mould growth. Peer-review under the responsibility of the organizing committee of the ICMB21.

This paper presents the results of a research on the influence of external pollution on the Indoo... more This paper presents the results of a research on the influence of external pollution on the Indoor Air Quality (IAQ) of classrooms naturally ventilated. The study was performed in a private school in Rancagua, a city located in Chile that has high levels of air pollution, especially during school time. The methodology included a combination of on-site monitoring, an occupant survey and a set of simulations carried out in CONTAM, a validated multi-zone airflow and contaminant transport model. The classrooms were simulated under various scenarios of outdoor pollution (PM 10 and PM 2.5) and ventilation rates. Results show that classrooms were highly affected by external contaminants and that penetration of outdoor pollutants occurred even with very low ventilation rates such as those provided purely by infiltration. The use of natural ventilation may not help to maintain adequate IAQ in schools if they are located in areas with high levels of external pollution and may affect, in a long-term, the health of children.

This paper presents the findings of a research study on the influence of outdoor pollution on the... more This paper presents the findings of a research study on the influence of outdoor pollution on the indoor air quality (IAQ) in naturally ventilated classrooms. The study was carried out in a school located in Rancagua (Chile), a city where annual average concentrations of particulate matter (PM10 and PM2.5) have been found to exceed several times the maximum levels as recommended by the World Health Organization (WHO). Classrooms were monitored and occupants surveyed to gain an understanding of the conditions affecting IAQ. In addition simulations using CONTAM, a validated software package, were carried out to predict the movement of pollutants within classrooms. The simulations considered two scenarios of outdoor PM10 and PM2.5, five ventilation rates (ACH) with no indoor sources of particulate matter (PM) and/or re-suspension effects. Results show that indoor concentrations of PM represent at least 40% of the outdoor levels even when all doors and windows are closed and ventilation...

This paper presents an initial investigation of the impact of different climate parameters on the... more This paper presents an initial investigation of the impact of different climate parameters on the hygrothermal performance of internal wall insulation systems. The study utilized WUFI, a software package that calculates transient heat and moisture transport in multi-layer building components. The effects of temperature, relative humidity, solar radiation, rainfall and wind speed were tested using data characteristic of 11 UK locations. Results indicated that rainfall and solar radiation have a major impact on the insulated wall’s ability to dry over time, while the effect of the other parameters was negligible. The hygrothermal behaviour of internally insulated brick walls was found to be affected by the wind-driven-rain and solar radiation climate parameters. Both parameters depend on orientation.

There is now widespread acceptance that mould growth in buildings should be avoided as it may lea... more There is now widespread acceptance that mould growth in buildings should be avoided as it may lead to adverse health effects. Consequently, it is critically important to have appropriate guidelines that address this issue. As well as reviewing the existing literature with regard to the state of the art of relevant mould-related research, this chapter reports on work aimed at developing mould-related Building Regulation guidance for dwellings in England and Wales. The major findings are, first, that although the factors that influence mould growth are well known, in buildings the variation and interrelationships of and between those are complex and, second, to deal with this complexity there is a fundamental choice between setting specific moisture performance criteria or using a ‘mould model’ to demonstrate compliance with regulations. At present, for England and Wales, the setting of moisture criteria is preferable and this chapter makes relevant suggestions for such criteria.

Intelligent Buildings International, 2014

This study aims to assess the adequacy of current guidelines, framed around thermal comfort, esti... more This study aims to assess the adequacy of current guidelines, framed around thermal comfort, estimated ventilation rates, and CO2 levels, for the provision of indoor air quality (IAQ) in school classrooms. It draws on detailed monitoring data from a sample of 18 classrooms from 6 London schools. Overheating during the non-heating season was identified in eight south-, south-east-, and east-facing classrooms in two Victorian and two contemporary schools. Four classrooms in these contemporary schools also failed to keep average indoor CO2 levels below 1500 ppm in the non-heating season. During the heating season, eight classrooms exceeded the daily average indoor CO2 levels. Mean indoor particulate matter (PM)10 and PM2.5 levels recorded in all classrooms in both seasons were higher than 20 and 10 μg/m3, respectively, indicating that school exposure during an academic year may exceed annual recommended WHO [2006. Air Quality Guidelines: Global Update 2005: Particulate Matter, Ozone, Nitrogen Dioxide, and Sulfur Dioxide. Copenhagen: WHO Regional Office for Europe; 2010. WHO Guidelines for Indoor Air Quality: Selected Pollutants. Copenhagen: WHO Regional Office for Europe.] guideline values in all classrooms. In both seasons, all classrooms were found to have indoor total volatile organic compounds levels (median: 269 ppb and interquartile range: 64–408 ppb) above guideline thresholds (130 ppb) associated with sensory irritations. Identification of specific volatile organic compounds indicated the presence of strong indoor sources including furniture, cleaning products, and teaching materials. Findings suggest that these school classrooms often have poor IAQ due to a combination of sub-optimal building operation and management practices. Furthermore, while CO2 and ventilation rates are a useful tool for IAQ assessment, findings indicate that consideration of specific pollutants is necessary to ensure a healthy indoor environment.

Moulds are organisms that may be found in both the indoor and outdoor environment. Moulds play an... more Moulds are organisms that may be found in both the indoor and outdoor environment. Moulds play an important role breaking down and digesting organic material, but, if they are significantly present in the indoor environment they may affect the health of the occupants. A relative humidity of 80% at wall surfaces is frequently stated as the decisive criterion for mould growth and methods used to assess the risk of mould growth are often based on steady state conditions. However, considering the dynamic conditions typically found in the indoor environment, a better understanding of the conditions required for mould to grow would seem desirable. This paper presents initial exploratory work to evaluate and assess 'WUFI-bio' - 'biohygrothermal' software that predicts the likelihood of mould growth under transient conditions. Model predictions are compared with large monitored data set from 1,388 UK dwellings before and after insulation and new heating systems are insta...

Indoor and Built Environment, 2014

This paper compares energy and ventilation performance, and levels of pollutants in six school cl... more This paper compares energy and ventilation performance, and levels of pollutants in six school classrooms and associates them to asthmatic and Sick Building Syndrome (SBS) symptoms and the perceived indoor air quality (IAQ) of students. Self-reported data on subjective perception of air quality and health responses were gathered with a standardised questionnaire completed by 151 school children (Response Rate (RR):86%) attending two schools in the Greater London Area: a contemporary suburban low carbon school building and an urban, high thermal mass school built in the 19th century. Temperature, particulate matter (PM), nitrogen dioxide (NO2), ozone (O3), and volatile organic compounds (VOCs) concentrations were monitored in three classrooms and one outdoor site in each school for 5 consecutive days during the heating seasons. Biological parameters were determined in settled dust and analysed with molecular methods. Overall, asthma prevalence in the school environment was associated...

Building Services Engineering Research and Technology, 2009

The importance of maintaining adequate indoor air quality in schools is recognised as a contribut... more The importance of maintaining adequate indoor air quality in schools is recognised as a contributing factor to pupils' learning performance. This paper describes a series of field measurements that investigating the ventilation rates in four recently built secondary schools in England. All schools were assessed for compliance with the recently adopted Building Bulletin 101, which defines the set of criteria in relation to the ventilation rates and indoor air quality in new school buildings. Using the obtained results a methodology has been suggested for post-occupancy evaluation of ventilation rates in schools. The suggested methodology draws particular attention to the dynamic nature of the interaction between the building and their occupants. Practical application: The new Building Bulletin 101 is quoted in Approved Document F as a means of compliance with Building Regulations for school buildings in the UK. This paper, based on four case studies, highlights some of the proble...

Hydrophobic (or water-repellent) treatments have been proposed to mitigate moisture risks associa... more Hydrophobic (or water-repellent) treatments have been proposed to mitigate moisture risks associated with Internal Wall Insulation when applied to solid masonry walls. This can reduce risks associated with moisture accumulation within the structure such as mould growth or the deterioration of joist ends and other embedded timber. However, such treatments slow down drying processes, and therefore may result in a net increase in moisture if the treatment is bypassed by e.g. cracks. Furthermore, such treatments have been linked with damage to external masonry surfaces. Freeze-thaw and salt crystallisation are the two main causes. Hygrothermal simulations may give some indication of risks but techniques to assess surface damage are either simplistic, impractical outside of the research environment, or both.

Energy and Buildings, 2019

Historical dwellings make up a significant fraction of the French building stock and require subs... more Historical dwellings make up a significant fraction of the French building stock and require substantial retrofitting to reduce their energy consumption and improve their thermal comfort. In the city center of Cahors, France, the old medieval dwellings are considered as valuable cultural heritage and internal insulation is often the only insulation technique that can be used when the architectural value of the exterior façade is to be preserved. However, internal insulation may have an impact upon the hygrothermal performance of the wall, leading to lowered drying capacity, with possible interstitial condensation and mold growth. Hygrothermal models may be used to assess the risk of failure, but the accuracy of the results depends on how reliable the input data is, including external boundary conditions, which may vary significantly in dense medieval cities such as Cahors. In this study, a Geographical Information System model of Cahors is used to develop EnergyPlus models of individual dwellings. The boundary conditions output by these models are, in turn, used to model the hygrothermal performance of façades with different internal insulations, using the hygrothermal tool Delphin. The Delphin outputs are then analyzed with the VTT model, a mold growth assessment model. Results highlight a quantitative correlation between some urban morphology characteristics and the hygrothermal performance of refurbished walls, with some configurations raising the risk of damage patterns. We find that bio-based insulation presents a better hygrothermal performance than mineral wool in most of the configurations.

UK authorities are promoting energy efficiency schemes to improve the performance of buildings as... more UK authorities are promoting energy efficiency schemes to improve the performance of buildings as a result of the high levels of energy consumption and consequent CO2 emissions. A quarter of these emissions are due to requirements for space heating. Installation of insulation is one of the most common alternatives to thermally improve buildings, especially on buildings built of solid masonry (~20 percent of the housing stock). However, the thermal improvement of buildings located in conservation areas, listed buildings, decorative façades, or traditional buildings could be only achieved through the use of internal wall insulation. Solid masonry walls with high surface water absorption coefficients have a higher dependence on external climate conditions (e.g. rain, solar radiation), which are likely to affect the performance of internal wall insulation. This paper examines the effect of walls orientation on the hygrothermal behaviour of an internally insulated 16th century building. ...

Energy and Buildings, 2013

The monitored performance of the first new London dwelling certified to the Passive House standar... more The monitored performance of the first new London dwelling certified to the Passive House standard is presented. The first detailed analysis of the energy consumption of the heating, ventilation and domestic hot water systems are given. The annual space heating demand of the 2 bedroom, 101m 2 dwelling was 12.1 kWh/m 2 , achieving the 15kWh/m 2 Passive House target. The annual primary energy demand was 125kWh/m 2 , marginally above the 120 kWh/m 2 target. The measured internal heat gains of 3.

The effect of changes in air humidity on historic tapestries

Historic tapestries are textile artworks usually found hanging inside historic buildings. They fo... more Historic tapestries are textile artworks usually found hanging inside historic buildings. They form part of the European heritage and have been exposed for centuries to diverse environmental conditions some of which have permanently damaged them. To inform better and appropriate conservation practices, their physical behavior when exposed to environmental changes must be understood. The research conducted aimed to assess how the internal environment conditions in a historic building affects the tapestries' structures and produce change in their strain. For this a series of experiments on a historic 19 th century tapestry inside an environmental chamber were carried out and cycles of moisture adsorption and desorption tested. Digital Image Correlation (DIC) and magnetic sensors developed by IBM were used to test successive stages of expansion and retraction of the tapestry given different levels of relative humidity (RH) in the environment. Peer-review under the responsibility of the organizing committee of the ICMB21.

Air sampling and analysis of indoor fungi : a critical review of passive (non- activated) and active (activated) sampling

For over a century, researchers have been concerned with what testing protocols to assess indoor ... more For over a century, researchers have been concerned with what testing protocols to assess indoor fungi growth were most reliable. To that end, various sampling and analysis methods were developed. However, to present no testing procedure has been standardised. The vast number of different fungi species, the differences in their biological properties and their implications on the occupants' health and building fabric can make the decision-making process for an appropriate assessment protocol challenging. This research aims to make a critical review of passive (or nonactivated) and active (or activated) sampling and emphasize potential errors while interpreting results obtained from passive or active protocols. Peer-review under the responsibility of the organizing committee of the ICMB21.

International Journal of Environmental Research and Public Health

Since the first case of COVID-19 was confirmed in China, social and physical distancing has been ... more Since the first case of COVID-19 was confirmed in China, social and physical distancing has been promoted worldwide as an effective community mitigation strategy. However, our understanding remains limited regarding how students would resume their activities and use of libraries when the restrictions to manage the spread of coronavirus were lifted. Understanding students’ seating behaviour in libraries is required to guarantee that the libraries meet the needs and preferences of students and promote students’ health and well-being and satisfaction with the library. This paper aims to explore the changes in the use of study spaces before and after the pandemic. Occupancy data from the UCL Bartlett Library collected at 10-min intervals from motion sensors located underneath desks was used to assess the occupancy within the library and which was then compared to characteristics of the space. This study revealed that the COVID-19 pandemic significantly impacted students’ use of the libr...

The use of ventilation holes in small micro-environments has been proposed as a mechanism to impr... more The use of ventilation holes in small micro-environments has been proposed as a mechanism to improve the environmental conditions of moisture and temperature within bookshelves. The National Trust, for example, has used these mechanisms to encourage air movement behind books as a possible strategy to reduce the risk of mould growth. It is believed that including ventilation holes as a passive design solution to promote airflow within micro-environments could prevent decay from occurring in archives of historic buildings. This paper investigates the mechanisms that cause airflow behind bookshelves using field measurements in three National Trust historical libraries. The measurements indicate that small but measurable velocities, up to 4 cm/s, can be generated passively behind bookshelves. Air movement in such confined micro-environments is caused by a combination of natural convection, caused by temperature differences between the interior and the exterior of the bookshelf(stack eff...

Building Services Engineering Research and Technology, 2021

Internal wall insulation is one of the few, possibly, the only feasible solution to efficiently r... more Internal wall insulation is one of the few, possibly, the only feasible solution to efficiently reduce heat losses through the external walls of buildings where the application of external insulation is not an option, for example, in conservation areas. However, the application of this intervention may lead to unintended consequences, such as moisture accumulation and mould growth. Currently, no international standards and regulations exist to evaluate these hazards via non-destructive inspections. Air sampling through impaction and culture-based analysis was suggested in previous research as a potential non-disruptive methodology for interstitial mould testing. The method requires the perforation of the inner side of a wall and the creation of airflow through the operation of a pump, to allow the collection of particles from the confined space of interest. The present study aimed to assess the location of perforations and their effect on the airflow created and the airflow pattern ...