A simple Mite Population Index (MPI) model is presented which predicts the effect on house dust mite populations of any combination of temperature and relative humidity (RH). For each combination, the output is an index, or multiplication factor, such that 1.1 indicates 10% population growth and 0.9 indicates 10% population decline. To provide data for the model, laboratory experiments have been carried out using lab cultures of Dermatophagoides pteronyssinus. The population change was observed for mites held in steady-state conditions at different combinations of temperature and RH over 21 days. From the results, a best-fit equation has been derived which forms the basis of the MPI model. The results also enable a new term to be defined: the Population Equilibrium Humidity, PEH, the RH for a given temperature at which house dust mite populations neither grow nor decline. It is similar to Critical Equilibrium Humidity, the RH below which house dust mites are unable to maintain water balance, but relates to a population of mites (rather than a physiological phenomenon) and is more able to take account of the observed effects of extremes of temperature and RH. Compared with previous population models, the MPI model is potentially more accurate and comprehensive. It can be combined with other simple models (described in previous papers), such as BED, which simulates the average hygrothermal conditions in a bed, given room conditions, and Condensation Targeter II, which simulates room conditions given a range of easily obtainable inputs for climate, house type and occupant characteristics. In this way it is now possible, for any individual dwelling, to assess the most effective means of controlling mite populations by environmental means, such as by improving standards of ventilation and insulation, or by modifying the occupant behaviour that affects the hygrothermal environment within a dwelling. Although the MPI model requires further development and validation, it has already proved useful for understanding more clearly how the different hygrothermal conditions found in beds and bedrooms can affect mite populations. It has also demonstrated that there is considerable scope for controlling mites by environmental means in cold winter climates such as the UK.

Condensation and mould growth is reported as being a problem in an estimated 4.2 million dwellings in England resulting in poor occupant health and substantial damage to the building fabric. This paper examines the development of an algorithm, Condensation Targeter, to predict the internal surface relative humidity and risk of mould growth in dwellings. The impact of cold bridging, seasonal variations, variable moisture production and hygroscopic materials are reviewed (but not interstitial condensation) and a comparison between modelled and measured data for 36 dwellings carried out. Results indicate that a steady-state model utilising Bredem-8 to predict internal temperatures and Loudon's condensation model to predict moisture shows good (± 10%) agreement with monitored data. A model sensitivity study shows that variations in occupant heating and density can be as, or even more, important in determining mould growth than ventilation.

Summary Buildings are designed for a specific climate yet they often have a lifetime of 100 years. Climate change may require a building to operate over a range of climatic conditions as a result of the impact of global warming. This effect is compounded by the fact that much of the climatic data currently used for design purposes is some 30 years old. This paper investigates the impact that climate change over the last two decades may have on the design and performance of buildings by examining the specific impact that changes in temperature and solar radiation have had on one particular design variable, energy use. The results indicate that the temperature and solar radiation in the London region of the UK has changed significantly in the last 15 years and that the climatic data currently being used for energy design calculations leads to inaccuracies in predictions of energy use. It is concluded that the climatic data used in these calculations should be urgently reviewed as it may be leading designers to adopt solutions which will be inappropriate for future use.

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It has been argued that Lean Construction (LC) offers the conceptual basis and the appropriate methods and tools needed for helping the construction industry meet the challenges of sustainable development. Since 1998, a growing body of knowledge has been emerging from the IGLC community, in relation to synergies between LC and Sustainability. Both seek to reduce waste and maximise value, but through different approaches and perspectives. The most common mistake, however, is a tool-focused framework for integration, which overlooks the conceptual differences between these two initiatives. The aim of this study, therefore, is to review the progress made in understanding the linkages and inconsistencies between the two initiatives, through conducting a critical systematic literature review (SLR) and synthesising the findings of 'LC and Sustainability' studies published in IGLC conferences over the past 25 years. The findings of the study provide an overview of previous studies about the topic, reveal major limitations in approaches to LC and Sustainable Construction (SC), and divulge significant opportunities for further work that remain unexplored.