Energy use in dwellings: decarbonising the stock and people

Energy use in dwellings: decarbonising the stock and peopl

Overheating in new homes: a new design tool

Kevin Lomas explains why the risk of overheating in homes is an increasing problem in the UK and elsewhere – in both existing buildings but also for the construction of new dwellings. To address this public health problem, a ground-breaking new tool has been developed and launched to assist designers, planners and clients to identify and reduce the risk of summer overheating in dwellings. A key benefit is its simplicity, early application in the design process, potential to inform design strategies and the provision of supporting background information and guidance. Further uses are envisaged, for example to identifying properties and rooms at risk of overheating – for public health compliance as well as education and training. Although this tool was developed for use primarily in the UK, it should inspire others around the world to take similar action.</div

High efficiency non-residential buildings: concepts, implementations and experiences from the UK

The UK has a national target to cut CO2 emission by 80% of the 1990 figure by 2050. This paper reflects on over 20 year of work into the design and operation of advanced naturally ventilated (ANV) buildings. The alternative forms of ANV building are described and measured CO2 emissions presented. The resilience of ANV buildings to anticipated changes in the UK climate are discussed. KEYWORDS Non-domestic buildings, advanced natural ventilation, carbon emissions, internal temperatures, future climate

Dynamic thermal simulation models of buildings: a new method for empirical validation

A new empirical validation methodology for dynamic thermal models has been devised and illustrated using the three models ESP, SERIRES and HTB2, and a simple data set collected from the Polytechnic of Central London test cells. The method hinges on making an initial base case prediction and then taking account of the errors and uncertainties in a systematic way. The method proved capable of revealing internal errors in thermal models. The relationship of this method to other validation techniques is discussed

Availability of monitored hourly building performance data for validating dynamic thermal models of buildings

As part of the SERC/BRE sponsored exercise to develop tools for validating dynamic thermal models, Leicester Polytechnic undertook a review and evaluation of monitored structures to identify data sets suitable as the basis for empirical validation tools. Over 580 monitored buildings located throughout the world were classified and assessed; all had produced hourly building performance data and had associated weather data. Data from only 18 structures, located at six sites in Europe and the USA, were deemed to be of high enough quality that they could be used for validating a wide range of complex dynamic and simpler thermal models. This Note gives an overview of the evaluation procedure, the types of data available and the major conclusions of the research

Frost susceptibility of granular materials

In this thesis work to improve the Transport and Road Research Laboratory (TRRL) frost heave test is described along with a new indirect method of predicting the frost susceptibility of granular material. To determine the optimum TRRL test conditions temperatures in the Nottingham University cold room and prototype Self Refrigerated Unit (SRU) were automatically monitored. In a typical trial several thousand temperatures were recorded. These were reduced to just three independent parameters, each of which quantified a particular feature of the temperature regime. Temperature fluctuations in the water bath of the prototype SRU were excessive and so an improved Mk3 unit was developed . Road sub-base aggregates covering a wide variety of geological types and grading were tested. These had the same heave after 250 hours freezing in the Mk3 SRU and the cold room, at least within the working range. Rigorous statistical analyses revealed that frost susceptibility could be judged with equal precision after only 96 hours freezing. The variability of heave was the same in both units. This variability was attributed to intrinsic differences between nominally similar specimens. It is intended that a 96 hour Mk3 SRU, frost heave test will be specified in a new British Standard. The indirect method is based on the suction/moisture content characteristics of granular soils. These were determined using the osmotic suction technique although the specimen preparation procedure had to be improved to accommodate the hard, coarse aggregates. For all the materials tested, the volumetric moisture content at suction of pF2.5 (ϴ2.5) was strongly correlated with heave in the TRRL test. Calculations revealed that, for the TRRL test conditions, pF2.5 is a suction which must occur in the zone between the terminal ice lens and the limit of ice penetration. It is thought that ϴ2.5 reflects the overall permeability of this frozen fringe

Summertime temperatures in 282 UK homes: thermal comfort and overheating risk

Summertime temperatures in UK homes are a matter of increasing concern, particularly because of global warming and an increased incidence of heat waves. Refurbishment adds to uncertainty about the resilience of UK homes to climate change. This paper examines internal summertime temperatures in the living and bedrooms of 282 homes in the UK city of Leicester. This is a statistically representative sample of the citys housing stock. The generally cool monitoring period included a short period of hot weather. Occupant behaviour had a significant impact on internal temperature, 13% of the homes were actively heated even during the spell of hot weather. In the 230 unheated homes, 28% of the living rooms and 88% of bedrooms were classed as severely overheated, as judged by the static, CIBSE, criteria. In contrast, 64% of the living rooms and 71% of the bedrooms were judged uncomfortably cool as defined by the BSEN15251 Cat II adaptive thermal comfort standard

Empirical validation of dynamic thermal computer models of buildings

A methodology for the validation of dynamic thermal models of buildings has been presented. The three techniques, analytical verification, inter-model comparisons and empirical validation have been described and their relative merits assessed by reference to previous validation work on ESP, SERIR'S, DEROB and BLAST. Previous empirical validation work on these models has been reviewed. This research has shown that numerous sources of error have existed in previous studies leading to uncertainty in model predictions. The effects of these errors has meant that none of the previous empirical validation studies would have produced conclusive evidence of internal errors in the models themselves. An approach towards developing tests to empirically validate dynamic thermal models is given

Coupled simulations for hygrothermal investigation of subterranean car parks and similar spaces

To investigate the hygrothermal conditions in subterranean car parks a twodimensional simulation procedure has been used, based on coupling the transient heat transfer programme HEAT with the dynamic thermal building simulation program TRNSYS. The likelihood of condensation and the rate of water deposition on surfaces were calculated with a new moisture model KOND. To estimate the consequence of moisture adsorption in materials in the hygroscopic range below saturation, the TRNSYS moisture capacitance model (buffer storage model) was used. A parametric study of the internal temperatures and the annual hours of condensation risk in underground car parks were conducted using German and UK climate data. The simulations indicate the relative risk of condensation occurring for different earth conditions, levels of insulation and air change rates, in spaces covered by earth and spaces covered by a heated building. It is shown that increased ventilation rates in summer can reduce condensation risk in underground car parks below heated buildings

No escape from the heat? Bedroom temperatures during England’s hottest summer

Numerous monitoring studies have demonstrated overheating of bedrooms in English homes during summer. Elevated bedroom temperatures can degrade sleep quality and impinge on health and well-being. This paper examines Public Health England’s advice to ‘move into a cooler room, especially for sleeping’ in hot conditions. Temperatures were monitored in 33 dwellings across the English Midlands between 1 May and 30 August 2018: the joint hottest English summer on record. The bedroom temperatures were analysed using the recommended CIBSE criterion that there should be no more than 1% of annual occupied hours over 26°C; adaptive comfort criteria are deemed inappropriate for sleeping persons. In half of the main bedrooms, temperatures exceeded 24°C for more than a third of sleeping hours. The CIBSE overheating criterion wasexceeded in 78% of master bedrooms. Even if everybody in a household slept in the coolest bedroom, 70% would still experience overheating. Assessing the living room as a bedroom led to a substantial reduction in homes classed as overheating. It is concluded that, whilst public health advice to seek cooler spaces during hot weather is well founded, such ‘safe havens’ for sleeping may exist only for a minority of English households. Further work is, however, needed.</div