An initial evaluation of a biohygrothermal model for the purpose of assessing the risk mould growth in UK dwellings

Moulds are organisms that may be found in both the indoor and outdoor environment. Moulds play an important rolebreaking down and digesting organic material, but, if they are significantly present in the indoor environment they mayaffect the health of the occupants. A relative humidity of 80% at wall surfaces is frequently stated as the decisivecriterion for mould growth and methods used to assess the risk of mould growth are often based on steady stateconditions. However, considering the dynamic conditions typically found in the indoor environment, a betterunderstanding of the conditions required for mould to grow would seem desirable. This paper presents initialexploratory 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 UKdwellings before and after insulation and new heating systems are installed (‘Warm Front’), the suitability of thissoftware as a tool to predict mould growth will ultimately be assessed. This paper presents some initial, exploratorywork

Climate Resilience of Internally-Insulated Historic Masonry Assemblies: Comparison of Moisture Risk under Current and Future Climate Scenarios

The conservation of cultural heritage built of historical brick masonry alongside meeting targets in energy reduction will most likely require widespread installation of internal wall insulation (IWI). In London, traditional buildings (pre-1919) make up 40% of the existing stock and insulating from the interior is a likely retrofit solution for solid brick walls. Adding insulation may introduce a higher risk to moisture accumulation and consequences such as mould growth and material decay. To investigate resilience to future moisture loads, three interior insulation assemblies (conforming to two U-value guidelines) were simulated in DELPHIN under reference, near-future (2040), and far-future climate (2080) scenarios. Calcium silicate, phenolic foam, and wood fibre assemblies were simulated. The reference year climate file was compiled from observed data and future files developed using the UK Climate Projections 2018 (UKCP18). Assemblies were evaluated for moisture accumulation, mould growth risk, and freeze-thaw (FT) risk. Results show low-to-medium risks in 2040 and high risks in 2080, assemblies of higher absorptivity and thinner insulation comparatively performing best. The calcium silicate assembly fared best for moisture performance; however, all assemblies will be subject to high moisture risk levels in the far future and responsible retrofits must take this and alternative design solutions into account

Development of predictive models for the probabilistic moisture risk assessment of internal wall insulation

Solid wall buildings account for a quarter of the UK building stock and need to be thermally upgraded to meet national greenhouse gas emission targets. Internal wall insulation (IWI) is often the only option for the retrofit of solid walls, especially when they are of architectural or historical interest. However, IWI can lead to moisture accumulation within the existing wall, affecting the structural integrity of the building and the health of occupants. To avoid these issues, a thorough risk assessment is necessary. This paper presents a method for developing predictive meta-models that can be used for a fast probabilistic moisture risk assessment of IWI, considering both the uncertainty and variability of input variables. First, in a Monte Carlo analysis, the uncertainty and variability of inputs were propagated through hygrothermal simulations. Then, generalised additive models for location, scale and shape (GAMLSS) were used to describe the relationship between inputs and response variables of the Monte Carlo analysis. The key input variables were identified by a global sensitivity analysis - using the elementary effects method - and in model building. Two types of response variable were considered for the models: variables based on percentage values (e.g. maximum relative humidity) and dose-response relationships (e.g. mould index). The paper shows that both risk assessment models had a good predictive power, highlighting the suitability of the developed method for the moisture risk assessment of the internal insulation of solid walls

Impact of the new Chilean air-tightness regulation on indoor air pollution in dwellings with inefficient heating sources

In 2014, the Chilean Ministry of Housing and Urban Planning (MINVU) began to develop regulations for maximum levels of air infiltration in dwellings. This paper investigates the impacts of increased air-tightness on indoor air quality (IAQ) and energy use. The study uses computer simulations representative of social housing in Temuco, a city with heavy urban air pollution and cold winters. Results show infiltration measures produced reductions of -49% in air changes and -17% in heating loads. Emissions from six different types of wood, gas and paraffin burners including PM10, PM2.5, NO2, CO, SO2 and PAHs were modelled. changes of between -3% to +35% in individual contaminant concentrations, revealing that increased air-tightness does not necessarily imply a reduction in IAQ due to variations in deposition rates and reduced external pollutant ingress. As heater emissions exceeded pollutant concentration limits between 1-41% of the time, adopting cleaner heating technology is recommende

The Impact of a Living Wall on the Air Quality in a WELL Certified Office Meeting Room: A Pilot Study

Research of living walls conducted in real life settings is limited. Analysis of how systems works in occupied office settings, can provide information to help reduce energy used in ventilation. Active living walls may offer an alternative to a regular mechanical ventilation as it reduces the need to extract and filter fresh air. Indoor air quality (IAQ) in the meeting room was tested in various scenarios using calibrated monitoring instruments. Preliminary results indicate that using the active living wall as the main mode of ventilation in the meeting space, temperature, CO2, and particulate matter (PM) levels were all within industrial benchmark guidelines. With further studies, different plant types, weather conditions and room sizes providing more in-depth knowledge that can be used to perfect the system, the hope of a future involving the switch from a traditional mechanical ventilation system to this innovative system may be viable

Towards an integrated moisture-safe retrofit process for traditional buildings in policy and industry

Improving the energy efficiency of traditional buildings, which represent a large proportion of the building stock in the UK, is necessary to meet national targets on greenhouse gas emissions and alleviate fuel poverty. Traditional dwellings in the UK are defined as hard-to-treat homes because insulating them is not cost-effective or might lead to moisture-related issues. This has led to efforts from policy-makers and organisations towards minimizing moisture risk in the energy-efficient retrofit of traditional buildings. This paper presents an overview of the work done towards a moisture-safe retrofit in the UK in the past ten years, focusing on the Government's policies and the work and legacy of the late Neil May, one of the pioneers in sustainable traditional buildings in the UK

Novel methodology for diagnosis of causes associated with mould growth in dwellings

Increased occupancy rates, inappropriate ventilation and intermittent heating regimes in dwellings can result in excessive atmospheric moisture levels, potentially leading to mould growth and lower indoor air quality. Identifying the causes associated to mould growth and taking correct remedial actions can be essential in reducing the prevalence of this problem. In practice it is often complex, even for experts, to accurately identify some of these causes and this can lead to costly and unnecessary interventions. Towards development of a novel systematic diagnostic procedure an extensive monitoring exercise has been undertaken involving collection of environmental data from dwellings with and without mould issues. The data has been analysed, considering building characteristics and occupancy's lifestyle features, with the objective to identify thresholds on measurable parameters that are indicative of mould growth risks. The proposed methodology links key parameters to identify factors that contribute to surface condensation and mould growth in buildings. This research presents a process towards environmental data collection, post-processing to compute and interpret pertinent environmental parameters, and displaying them in a clear and easy-to-interpret manner

The monitored performance of the first new London dwelling certified to the Passive House standard

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, 101 m2 dwelling was 12.1 kWh/m2, achieving the 15 kWh/m2 Passive House target. The annual primary energy demand was 125kWh/m2, marginally above the 120 kWh/m2 target. The measured internal heat gains of 3.65 W/m2 are much greater than the 2.1 W/m2 suggested as standard for dwellings. The Passive House Planning Package, PHPP, is found to be a good predictor of space heating demand and the risk of summer time over heating. Winter space heating demand is sensitive to occupant blind use. With a total metered energy consumption of 65 kWh/m2, the Camden Passive House is one of the lowest energy, small family dwellings, monitored in the UK

Estimating the impact of reveals on the transmission heat transfer coefficient of internally insulated solid wall dwellings

Internal wall insulation as a retrofit measure could help to reduce energy use and greenhouse gas emissions in many of the 6 million solid wall buildings in the UK. However during retrofit, junctions that are hard to deal with are often left uninsulated, increasing heat loss and surface mould growth risk at thermal bridges. Furthermore the effect of junctions, insulated or uninsulated is not properly taken into account in commonly used assessments of heat loss. This paper presents a study on the impact of the junctions around openings, also called reveals, on the transmission heat transfer coefficient of internally insulated dwellings and a discussion on potential areas of improvement of common assessment tools for retrofit. Findings showed that reveals account for the majority of the transmission heat transfer coefficient at junctions, that thicker wall insulation is not necessarily advantageous from a heat loss perspective, and that the transmission heat transfer coefficient at junctions per unit area of exposed elements was often higher than the reference value used in the UK

Evaluating Housing Health Hazards: Prevalence, Practices and Priorities in Delhi's Informal Settlements

Housing quality is crucially linked to health and sustainability goals, yet there is limited research on informal housing and settlements where housing quality is poor, and the health risks are expected to be greatest. This paper describes the investigation of housing conditions in a low-income resettlement colony in Delhi. A novel transdisciplinary methodology to evaluate multiple housing health hazards and establish intervention priorities in participation with the community was developed. Findings from housing surveys and indoor environmental monitoring were contrasted with a participatory self-assessment—revealing the widespread prevalence of hazards and suboptimal housing conditions as well as substantial differences in priorities, and thus perspectives, between participants and researchers. Focus group discussions explored the findings and built consensus on priorities. Our findings uncovered how poor housing conditions affect daily practices and thus are likely to adversely affect socio-economic development and gender equality. We highlight limitations in current frameworks to assess housing hazards and argue that a transdisciplinary approach is vital to provide a holistic understanding and to develop effective interventions. These insights are crucial to inform inclusive solutions for adequate housing and human settlements that can support improved health and help achieve the sustainable development goals