The effect of Turbulence Models on Numerical Prediction of Air Flow within Street Canyons

November 15-17, Belgrad

Evaluation of life cycle carbon impacts for higher education building redevelopment: a multiple case study approach

UK higher education institutions have strong drivers to reduce operational carbon emissions through building redevelopment. The life cycle carbon impact of buildings − operational and embodied carbon − is a developing area of consideration, particularly in redevelopment. A case study analysis was employed to assess how redevelopment interventions can reduce life cycle carbon impacts. The five case study buildings covered a variety of activities, construction styles, systems and operational characteristics. Each building was monitored over a 12-month period and the data was combined with metered energy use to calibrate life cycle carbon base models following the BS EN 15978:2011 standard. The base models were modified to simulate a range of carbon reduction interventions and also new-build to current UK energy efficiency regulations. The design stage uncertainty was factored in. The best-case refurbishment options showed average life cycle carbon savings of between 20 and 29%, with the most effective intervention varying by building. For new-build, the savings ranged from 32–64%, with the greatest being for conversion from mechanical to natural ventilation. The average contribution of embodied carbon to total life cycle carbon impact for the new-builds varied from 6% for the chemistry building to 23% for the law building

Evaluation of life cycle carbon impacts for higher education building redevelopment: an archetype approach

An archetype-based approach was taken to generalise case study findings on the life cycle carbon impacts of higher education building redevelopment. For each archetype, the life cycle operational and embodied carbon impacts of carbon reduction interventions and building redevelopment options were analysed. The contribution of embodied carbon to total life cycle carbon impact was also evaluated. A database of English and Welsh university buildings was constructed comprising energy and geometry data. Six archetypes for pre-1985 buildings were then determined based on academic activity and servicing strategy. Buildings were synthesised for each archetype using case study data and the database geometry data. Life cycle carbon models following the BS EN 15978:2011 standard were constructed, calibrated using the database energy data and used to simulate carbon reduction interventions and new-build schemes. Various material systems were considered and design stage uncertainty was factored in. For new-build, average life cycle carbon savings ranged from 37 to 54%, exceeding the range of 25–33% for the best-case refurbishment options. However, in some cases the differences were only slight and within the range of uncertainty. Structural systems and building services dominated material impacts, the latter owing to replacement cycles. The generalised findings were used to provide guidance on higher education carbon management

Condensation risk: comparison of steady-state and transient methods

Accurate assessment of both surface and interstitial condensation risk is important not only to reduce the damaging effect of moisture within the structure of buildings, but also to provide a healthy environment free from mould growth. The current British Standard (BS EN ISO 13788: 2002) contains an assessment procedure based on the assumption of a steady-state heat flow through the building envelope, neglecting the transient nature of the problem. This paper compares and evaluates numerical results of the condensation risk calculation under both steady-state and transient conditions using the existing numerical codes. Significant differences are apparent between the predictions of the simple (steady-state) and complex (transient) methods for all construction details modelled

Method development for measuring volatile organic compound (VOC) emission rates from spray foam insulation (SPF) and their interrelationship with indoor air quality (IAQ), human health and ventilation strategies

The polyurethane foam industry is projected to reach a worldwide value of up to $74bn by 2022 and with airtightness of new and retrofitted properties continually increasing, an important question arises: what is the impact of these materials on the indoor air quality (IAQ), occupants’ health and indoor environment? As the foams are made in-situ through an exothermic reaction between two chemical mixtures (side A and side B), volatile organic compounds (VOCs) are emitted during their application and curing process. Current research, commercial practices and governmental advice suggests that emissions decrease over time and 8-24 h after application are usually sufficient for residents to return safely to their properties. However, there is still a lack of case studies and a fundamental absence of robust analysis on how ventilation strategies affect long term off-gassing rates and chemical emission quantities. The emission rates from SPF materials could have a direct impact on IAQ if they exceed the occupational exposure rates recommended by NIOSH, or other professional associations. But the difficulty in recording these emission rates is evident as there is still a lack of an international standard for their quantification. To address this issue, we have developed an analytical methodology for measuring some of the composition materials of the foams and residual products associated with their application. The experiment consisted of two stages- active air sampling of spray foam emissions and spiking desorption tubes with a standard solution in order to develop calibration curves. The solution included SPF compounds, or by-products from their application, associated with possible acute impact on health: 1,4 dioxane, chlorobenzene, dibutyltin dilaurate, triethyl phosphate and bis(2-dimethylaminoethyl)ether. We managed to detect five of the chemicals of interest through air sampling and produce calibration curves for 1,4 dioxane, chlorobenzene and triethyl phosphate, which would allow us to quantify the emission rates at the next stage of research. The results of the experiments successfully demonstrated proof of concept quantitative methodology for the compounds of interest. With further research and experiments, this technique has the capacity to be developed into an international standard for measuring VOCs from spray foam emissions and other buildings products. This would provide scientists and industry professionals with the tools to further develop retrofit and ventilation strategies in order to provide healthier buildings

An evaluation of the hygrothermal performance of 'standard' and 'as built' construction details using steadystate and transient modelling

Accurate assessment of both surface and interstitial condensation risk at the design stage of buildings is of great importance - not just to minimise the damaging effects moisture can cause to building envelopes, but also to contribute to the provision of adequate indoor air quality. Guidance certainly does exist with regards to limiting thermal bridging in order to prevent condensation occurring on new constructions. However, a recent study has provided clear evidence that the reality, both in translating the available guidance into a specific design and in construction on site is often rather different from the 'ideal'. This paper reports on that study and compares and evaluates the hygrothermal performance of construction details for different phases during the building life cycle. The results of both the surface and interstitial condensation risk simulations under both steady-state and transient conditions are presented and discussed. Significant differences in the hygrothermal performance of 'standard' and 'as built' construction details are observed

Condensation risk – impact of improvements to Part L and robust details on Part C Final report: BD2414

This report summarises the main findings of the project ‘Impacts of Improvements to Part L and Robust Construction Details (RCD) on Part C’. The work consisted of a fieldwork element, undertaken by Leeds Metropolitan University and a modelling element carried out by University College London. Details of the work programme are contained in Appendix 1. The fieldwork consisted of the analysis of design material and site surveys from 16 housing developments constructed to Part L 2002 and adopting the Robust Construction Detail route to compliance. The modelling element of the project sought to identify the extent to which the ‘as built’ details give rise to a significantly increased condensation risk as compared to the relevant ‘standard’ robust construction details, as defined in the guidance. In addition to assessing ‘as built’ performance, the modelling phase of the project has investigated the suitability of the relevant calculation methods used to assess the risk of surface and interstitial condensation and mould growth. This report draws together the important conclusions from the project which has previously been presented in several very detailed interim reports and also for the first time presents the results of a workshop where these results were discussed to obtain industry feedback. The overall conclusions, future work and dissemination plans are also presented

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

Building Schools for the Future: Lessons Learned From Performance Evaluations of Five Secondary Schools and Academies in England

Building performance evaluations (BPE) of five secondary schools and academies constructed under the Building Schools for the Future (BSF) programme in England found that CO2 emissions associated with operational energy performance in all these buildings is higher than the median of the secondary schools. Whilst the new regulatory requirements for building fabric performance have led to some improvements in heating energy when compared against good practice and typical benchmarks, there is still significant discrepancy between heating energy use and the design expectations. Electricity use in these buildings is also 37–191% more than the median school and significantly worse than the design expectations. These results point to the importance of post-occupancy building fine-tuning and measurement and verification of performance in-use with respect to design projections to narrow the performance gap. It is also necessary to set out clear operational performance targets and protect energy efficiency measures from value engineering throughout building procurement and in operation to achieve good level of performance. Finally, it is suggested to adopt a holistic view of energy, environmental quality, and educational performance to have a better understanding of schools' performance and potential conflicts between energy efficiency measures and indoor environmental quality (IEQ)

Life cycle energy efficiency in building structures: A review of current developments and future outlooks based on BIM capabilities

The continuous developments of Building Information Modelling (BIM) in Architecture, Engineering and Construction (AEC) industry supported by the advancements in material resourcing and construction processes could offer engineers the essential decision-making procedures to leverage the raising demands for sustainable structural designs. This article brings together the theory of Life Cycle Assessment (LCA) and the capabilities of BIM to survey the current developments in the energy efficiency of structural systems. In addition, the article explores the engineering dimensions of common decision-making procedures within BIM systems including optimisation methods, buildability and safety constraints and code compliance limitations. The research presents critical expositions in both engineering and sustainable energy domains. The article then argues that future innovations in the sustainable decision-making of buildings’ structures would require BIM-integrated workflows in order to facilitate the conflicting nature of both energy efficient and engineering performance indexes. Finally, the study puts forward a series of research guidelines for a consolidated decision paradigm that utilises the capabilities of BIM within the engineering and sustainable energy domains in a synergistic manner