Promoting energy efficiency in the private rented sector

The English House Condition Survey for 1991 demonstrated that levels of energy efficiency in private rented property are significantly below other sectors, even though energy improvements have tangible benefits for landlords. The low level of energy efficiency provision in the private rented sector indicates that landlords are unaware or unconvinced of these benefits and market barriers may have restricted uptake. Information regarding energy efficiency advice to the private rented HMO sector has focussed on offering good practice design guidance, and information about the level of fitness and overall characteristics of the sector. This research project evaluated the PRESS scheme, which encouraged landlords to introduce energy efficiency measures. A total of 78 private sector rented properties in Sheffield were analysed with retrofit measures to improve levels of energy efficiency. The results demonstrate that whilst market barriers exist, the PRESS scheme went some way to overcoming some barriers to energy efficiency.<br /

Dynamic thermal simulation of advanced natural ventilation in buildings : current and future usage, UK exemplar

This paper evaluates the use of advanced natural ventilation (ANV) strategies in a range of climatic conditions from four cities in the UK. A prototype ANV system was proposed to determine the most effective case in mitigating overheating. The case was then assessed under identical simulation conditions for all four ANV strategies. The overheating criteria used in the research include the single temperature criterion from CIBSE Guide A and the adaptive thermal comfort overheating criteria from BS EN 15251. Both the current and future ‘Design Summer Year (DSY)’ weather data were used to examine the thermal performances of the proposed design. The findings show that shading, night cooling and heavy weight structures (ceiling) were all useful in mitigating overheating, with night cooling being identified as the most effective measure. The work assessed the use of ANV in both current and future scenarios to quantify the limits of outdoor environmental conditions under which natural ventilation is an effective strategy for achieving thermal comfort. The adaptive thermal comfort overheating criteria were proved to be easier to meet compared with the CIBSE single temperature criterion. With the adaptive overheating criteria, the given design is predicted to not overheat until 2050 in London Heathrow; and for other places evaluated in the UK (Edinburgh, Manchester & Birmingham), the design passes these criteria. The Centre-in ANV strategies proved to be more effective than the Edge-in strategies for space cooling due to the extended structure thermal mass

Extreme and near-extreme climate change data in relation to building and plant design

Buildings and plant are designed utilizing near-extreme weather data. The present data used are briefly discussed, including manual near-extreme percentiles for manual design and hourly data for simulation on a PC (test reference years and design summer years, and near-extreme periods). However, with climate change occurring, designs based on current data will produce uncomfortable summer thermal conditions within and around buildings in the future. This expected change is especially relevant now, as buildings have to last typically from 50 to 100 years. Climate change data for the future are needed to assess the performance of buildings and plant in the future. The Hadley Centre climate change models could provide such data. In this paper analysis of extreme data from one model, the HadCM3 model (south-east England grid box) with an appropriate climate change scenario, are considered in relation to their use for design assessment. Dry bulb temperature and solar irradiance extreme values are considered in this paper. The expected trend in both minimum and maximum temperature is for both to increase with time, but the maxima are found to rise faster than the minima. There are two factors influencing the solar radiation estimates, the basic clarity of the atmosphere and the seasonal amount of cloud. The latter is predicted to increase slightly in winter and decrease slightly in summer. The variations in the predicted short-wave radiation values reflect the expected combined impacts of these two factors. The implications of these results are briefly discussed.</p

Numerical studies of displacement natural ventilation in multi-storey buildings connected to an atrium

This paper describes computational fluid dynamics (CFD) simulations used to investigate displacement natural ventilation in simple multi-storey spaces connected to an atrium. The purpose of the work is to demonstrate the potential of CFD for modelling these airflows using solutions from simple mathematical models and salt bath experiments to provide an indication of the accuracy that can be attained. The storeys are connected to an atrium and air flows into them via top-down-chimneys. The driving force is provided by localised point heat sources on each floor which generate buoyant plumes that entrain the surrounding air and transport warm air upwards forming a warm, stratified layer in each storey. The mathematical models are used to describe the main flow features, such as stratification height, temperature gradient and ventilation flow rate. Results showed that, using the RNG k-epsilon" turbulence model, the predicted airflow patterns, temperature profiles and ventilation flow rates agreed favourably with the mathematical models, demonstrating the potential of using CFD for modelling buoyancy-driven displacement ventilation in multi-storey spaces connected to an atrium