Towards measurement and verification of energy performance under the framework of the European directive for energy performance of buildings

Directive 2002/91/EC of the European Parliament and Council on the Energy Performance of Buildings has led to major developments in energy policies followed by the EU Member States. The national energy performance targets for the built environment are mostly rooted in the Building Regulations that are shaped by this Directive. Article 3 of this Directive requires a methodology to calculate energy performance of buildings under standardised operating conditions. Overwhelming evidence suggests that actual energy performance is often significantly higher than this standardised and theoretical performance. The risk is national energy saving targets may not be achieved in practice. The UK evidence for the education and office sectors is presented in this paper. A measurement and verification plan is proposed to compare actual energy performance of a building with its theoretical performance using calibrated thermal modelling. Consequently, the intended vs. actual energy performance can be established under identical operating conditions. This can help identify the shortcomings of construction process and building procurement. Once energy performance gap is determined with reasonable accuracy and root causes identified, effective measures could be adopted to remedy or offset this gap

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

An experimental study of spray foam insulation products - evidence of 1,2-dichloropropane and 1,4-dioxane emissions

An experimental study was conducted using SPME-GC-MS and TD-GC-MS to analyse VOC emissions from three spray foam insulation products. Two closed cell and one open cell materials were tested using SPME-GC-MS passive sampling and a range of VOCs were found with 1,2- dichloropropane (1,2-DCP) found in all products. TD-GC-MS analysis of product 1 (a closed cell foam) and the raw material used for its production (B-side) showed that 1,4-dioxane and 1,2-DCP were both present in the raw material and emitted from the cured foam product. Our findings are currently limited and preliminary, but do seem to indicate that industrial contamination of raw chemicals could be the likely source of these compounds. This could raise the issue of Class 1 and 2B carcinogen VOCs being present in raw polyurethane spray foam insulation (SPF) materials should systematic evidence is provided. As per WHO guidance, it would be a better strategy to remove pollutants at the source. Further research will aim to quantify emission concentrations during application and examine the impact of application strategies

A comparative study of benchmarking approaches for non-domestic buildings: Part 1 – Top-down approach

Benchmarking plays an important role in improving energy efficiency of non-domestic buildings. A review of energy benchmarks that underpin the UK’s Display Energy Certificate (DEC) scheme have prompted necessities to explore the benefits and limitations of using various methods to derive energy benchmarks. The existing methods were reviewed and grouped into top-down and bottom-up approaches based on the granularity of the data used. In the study, two top-down methods, descriptive statistics and artificial neural networks (ANN), were explored for the purpose of benchmarking energy performances of schools. The results were used to understand the benefits of using these benchmarks for assessing energy efficiency of buildings and the limitations that affect the robustness of the derived benchmarks. Compared to the bottom-up approach, top-down approaches were found to be beneficial in gaining insight into how peers perform. The relative rather than absolute feedback on energy efficiency meant that peer pressure was a motivator for improvement. On the other hand, there were limitations with regard to the extent to which the energy efficiency of a building could be accurately assessed using the top-down benchmarks. Moreover, difficulties in acquiring adequate data were identified as a key limitation to using the top-down approach for benchmarking non-domestic buildings. The study suggested that there are benefits in rolling out of DECs to private sector buildings and that there is a need to explore more complex methods to provide more accurate indication of energy efficiency in non-domestic buildings

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

Polyurethane insulation and household products – A systematic review of their impact on indoor environmental quality

We systematically review the impact of polyurethane insulation and polyurethane household products on the indoor environmental quality of buildings. The review breaks down polyurethane products into constituent compounds (isocyanate, polyol, flame retardant, blowing agent and catalyst) as well as secondary emissions, and discusses their implications on human health. Concentrations of compounds emitted from insulation, and household materials, measured in laboratory experiments and case studies are presented in the context of the built environment. We outline that isocyanate exposure over the current legal limits could take place during spray foam insulation application in the absence of personal protection equipment. The study reports that flame retardants are not chemically bound to polyurethane products and they are found in measurable concentrations in indoor environments. Additionally, we provide evidence that catalysts are responsible for at least some negative impact on perceived indoor air quality. More data is required to determine the long-term emissions from spray foam products and the ventilation strategies required to balance energy savings, thermal comfort and good indoor air quality. However, it is not yet possible to determine whether potential health impacts could result from exposure to a single compound or a combination of compounds from spray foam products. We present a risk matrix for polyurethane compounds and propose that flame retardants, by-products, and residual compounds are particularly important for indoor air quality. We conclude by suggesting a framework for further research

Robots can reduce the exposure of people to volatile organic compounds (VOCs) during application of spray foam insulation

An experimental study was conducted to determine whether, and by how much, worker exposure to volatile organic compounds (VOCs) would be reduced when robots are used to apply spray foam insulation. The study was undertaken in a test room where the ventilation rates were controlled and temperature and relative humidity were recorded. Four independent spraying experiments were conducted where robots were used to spray foam onto a suspended timber floor. The environmental conditions were recorded and VOCs were actively sampled using thermal desorption tubes during the periods of spraying (15 min) and curing (10 min). The tubes were analysed using thermal desorption-gas chromatography- mass spectrometry (TD-GC-MS). Four VOCs were quantified in two locations- near the spraying surface and near the worker operating the robot (outside the room). Measurable concentrations of 1,2-dichloropropane, 1,4-dioxane, chlorobenzene and triethyl phosphate (TEP) were quantified inside the room, whilst the concentration near the worker were below the detection limits. The experiment indicates that if workers wear ineffective personal protection equipment, they could be exposed to multiple airborne pollutants due to their close proximity to the spraying surface. Our study is the first to quantify the reduction of workers exposure to four VOCs when robots are used compared to conventional manual spraying