Case Study Dwellings Research Articles

Urban social housing resilience to excess summer heat

The potential levels of exposure to indoor overheating in an urban environment are assessed for vulnerable social housing residents. Particular focus is given to the synergistic effects between summertime ventilation behaviour, indoor temperature and air pollutant concentration in relation to energy retrofit and climate change. Three different types of social housing are investigated (1900s’ low-rise, 1950s’ mid-rise and 1960s’ high-rise). The case study dwellings are located in Central London and occupied by vulnerable individuals (elderly and/or people suffering from ill-health or mobility impairment). Indoor temperature monitoring suggests that occupants are already exposed to some degree of overheating; the highest levels of overheating occur in 1960s’ high-rise tower blocks. The thermal and airflow performance simulation of a mid-floor flat in the 1960s’ block under the current and projected future climate indicates that improved natural ventilation strategies may reduce overheating risk to a certain extent, with night cooling and shading being slightly more effective than all-day rapid ventilation. However, their potential may be limited in future due to high external temperatures and the undesired ingress of outdoor pollutants. This highlights the need for the development of combined strategies aiming to achieve both indoor thermal comfort and air quality.

Bridging the domestic building fabric performance gap

It is recognized that there is often a discrepancy between the measured fabric thermal performance of dwellings as built and the predicted performance of the same dwellings and that the magnitude of this difference in performance can be quite large. This paper presents the results of a number of in-depth building fabric thermal performance tests undertaken on three case study dwellings located on two separate Passivhaus developments in the UK: one masonry cavity and the other two timber-frame. The results from the tests revealed that all the case study dwellings performed very close to that predicted. This is in contrast with other work that has been undertaken regarding the performance of the building fabric, which indicates that a very wide range of performance exists in new-build dwellings in the UK, and that the difference between the measured and predicted fabric performance can be greater than 100%. Despite the small non-random size of the sample, the results suggest that careful design coupled with the implementation of appropriate quality control systems, such as those required to attain Passivhaus Certification, may be conducive to delivering dwellings that begin to ‘bridge the gap’ between measured and predicted fabric performance.

Methods for assessing domestic overheating for future building regulation compliance

Due to both changing building design and projected climate change, the conditions within dwellings in the UK are likely to show increased risk to overheating. There is therefore a growing requirement for a suitable industry standard to assess overheating risk in the domestic sector, ensuring that both new dwellings and refurbishments to existing dwellings take future climate into account. This study compares the type of advice gained and the form of calculation used for a series of different summertime overheating analyses. Using simple overheating definitions, a case-study dwelling is simulated for two UK locations across different climate scenarios and the consistency in advice provided by the chosen methods is discussed. The results suggest there are issues around the consistency of such varied models, but also highlight the need to strike a balance between a method that reliably accounts for building thermal performance while also providing a clear and useable approach that can be adopted within industry practice.

Development of a methodology for life cycle building energy ratings

Traditionally the majority of building energy use has been linked to its operation (heating, cooling, lighting, etc.), and much attention has been directed to reduce this energy use through technical innovation, regulatory control and assessed through a wide range of rating methods. However buildings generally employ an increasing amount of materials and systems to reduce the energy use in operation, and energy embodied in these can constitute an important part of the building's life cycle energy use. For buildings with ‘zero-energy’ use in operation the embodied energy is indeed the only life cycle energy use. This is not addressed by current building energy assessment and rating methods. This paper proposes a methodology to extend building energy assessment and rating methods accounting for embodied energy of building components and systems. The methodology is applied to the EU Building Energy Rating method and, as an illustration, as implemented in Irish domestic buildings. A case study dwelling is used to illustrate the importance of embodied energy on life cycle energy performance, particularly relevant when energy use in operation tends to zero. The use of the Net Energy Ratio as an indicator to select appropriate building improvement measures is also presented and discussed.

The impact of energy efficient refurbishment on the space heating fuel consumption in English dwellings

The aim of this study is to examine the effect of a major domestic energy efficiency refurbishment programme on domestic space heating fuel consumption. The case study dwellings were monitored either before or after (or both) the introduction of energy efficiency retrofit measures such as cavity wall insulation, loft insulation, draught stripping and energy efficient heating system. Property and utility consumption data were collected and half-hourly living room and main bedroom temperatures were monitored for 2–4 week period over two winters from a total of 1372 households selected from five major urban areas in England. Space heating fuel consumption was normalized to account for variation in the indoor–outdoor temperature difference and the dwelling floor area. The findings show that cavity wall and loft insulation can reduce the space heating fuel consumption by 10% in centrally heated properties and 17% in non-centrally heated properties. However, the introduction of a gas central heating system, although theoretically more efficient, has no significant impact in reducing fuel consumption even after adjusting for increased internal temperature.