Tim Sharpe

An assessment of environmental conditions in bedrooms of contemporary low energy houses in Scotland

This paper describes the monitored environmental conditions in the bedrooms of 26 low energy houses in Scotland, include both naturally ventilation and houses with mechanical ventilation with heat recovery systems (MVHR). The context of the paper is the performance gap that is emerging between design predictions and actual performance of housing, and this paper focuses on the environmental performance of bedrooms. Bedrooms are of particular interest as they are the spaces in which occupants have the greatest exposure to the indoor environment, and in which conditions are relatively constant. The study indicates that ventilation is generally poor in these spaces and that both temperature and humidity frequently exceed accepted parameters for comfort and health. Increased window opening is a mitigating factor, but effects are limited by overall ventilation strategies.

Building tight – ventilating right? How are new air tightness standards affecting indoor air quality in dwellings?

Building more air-tight dwellings is having a deleterious impact on indoor air quality. In a range of recently completed dwellings CO2 concentrations were measured in occupied bedrooms at unacceptable concentrations (occupied mean peak of 2317 ppm and a time weighted average of 1834 ppm, range 480–4800 ppm). Such high levels confirm that air-tight dwellings with only trickle ventilators as the ‘planned’ ventilation strategy do not meet the standards demanded by the Building Regulations. Reducing ventilation rates to improve energy efficiency and lower carbon emissions, without providing a planned and effective ventilation strategy is likely to result in a more toxic and hazardous indoor environment, with concurrent and significant negative long-term and insidious impacts on public health. Furthermore, the methodology underpinning the current regulations cannot be considered as creditable. While the complexity around numerical modeling often leads to conclusions based upon simplistic and unrealistic assumptions around all doors in a dwelling being open and trickle ventilators being unobstructed, this paper demonstrates that in ‘real life’ situations, this is not the case and could lead to significant risks of under ventilation. This is particularly the case when standards and guidance are based upon theoretically modeled scenarios that are not representative of real-life operation. The consequences of this are important in terms of the likely negative impacts on occupant health.

Occupant Interactions and Effectiveness of Natural Ventilation Strategies in Contemporary New Housing in Scotland, UK

The need to reduce carbon emissions and fuel poverty has led to increased building envelope air tightness, intended to reduce uncontrolled ventilation heat losses. Ventilation strategies in dwellings still allow the use of trickle ventilators in window frames for background ventilation. The extent to which this results in “healthy” Indoor Air Quality (IAQ) in recently constructed dwellings was a concern of regulators in Scotland. This paper describes research to explore this. First a review of literature was conducted, then data on occupant interactions with ventilation provisions (windows, doors, trickle vents) gathered through an interview-based survey of 200 recently constructed dwellings, and measurements made on a sample of 40 of these. The main measured parameter discussed here is CO2 concentration. It was concluded after the literature review that 1000 ppm absolute was a reasonable threshold to use for “adequate” ventilation. The occupant survey found that there was very little occupant interaction with the trickle ventilators e.g., in bedrooms 63% were always closed, 28% always open, and in only 9% of cases occupants intervened to make occasional adjustments. In the measured dwellings average bedroom CO2 levels of 1520 ppm during occupied (night time) hours were observed. Where windows were open the average bedroom CO2 levels were 972 ppm. With windows closed, the combination of “trickle ventilators open plus doors open” gave an average of 1021 ppm. “Trickle ventilators open” gave an average of 1571 ppm. All other combinations gave averages of 1550 to 2000 ppm. Ventilation rates and air change rates were estimated from measured CO2 levels, for all dwellings calculated ventilation rate was less than 8 L/s/p, in 42% of cases calculated air change rate was less than 0.5 ach. It was concluded that trickle ventilation as installed and used is ineffective in meeting desired ventilation rates, evidenced by high CO2 levels reported across the sampled dwellings. Potential implications of the results are discussed.

Meta-analysis of indoor temperatures in new-build housing

ABSTRACT Despite growing concerns about overheating, a lack of evidence exists on the scale of the problem, particularly in contemporary UK housing. This paper presents the results of a meta-analysis of indoor temperatures in selected low-energy housing. Temperature data recorded at five-minute intervals in 60 dwellings across 19 demonstration projects (2012–14) were collated and analysed to investigate the prevalence of overheating. Findings evidence high summertime temperatures, with 27% of living rooms exceeding 28°C during August. Based on the Chartered Institution of Building Services Engineers (CIBSE) threshold of 5% annual occupied hours > 25°C, 57% of bedrooms and 75% of living rooms were classified as having overheated. Overall, 30% of living rooms exceeded the adaptive comfort threshold of > 3% occupied hours ΔT ≥ 1 K. The results suggest a fundamental relationship between ventilation and indoor temperatures. The higher minimum and average summertime temperatures observed in mechanical ventilation with heat recovery (MVHR) homes (p < 0.05) and lower temperature range (p < 0.001) suggest the need for greater attention to adequate summertime ventilation provision in airtight homes. The results demonstrate a high prevalence of overheating in exemplary housing, indicating the need for greater efforts to ensure the effective implementation of strategies to minimize overheating and improve ventilation in low-energy homes.

Adapting the Scottish tenement to twenty‐first century standards : An evaluation of the performance enhancement of a nineteenth century “Category B” listed tenement block in Edinburgh

Purpose – The stone tenement is perhaps the most iconic type of housing in Scotland and to a large extent defines the built environment of its major cities and towns. However in the context of the climate change agenda which demands reduced energy consumption and CO2 production, such buildings are recognised to be a particular challenge in terms of both their poor energy performance, but also the limitations on improvement measures that do not have a detrimental affect on their form and appearance. As a result interventions that improve performance tend to less mainstream and it is therefore import to assess the effectiveness of these, and this was the purpose of the research.Design/methodology/approach – This paper describes the findings of a post occupancy evaluation that examined the user satisfaction and energy performance of a recently completed (2008) adaptive rehabilitation project of a listed 19th Century sandstone tenement block in Edinburgh city centre. the project undertook a short intensive mo...The stone tenement is perhaps the most iconic type of housing in Scotland and to a large extent defines the built environment of its major cities and towns. However in the context of the climate change agenda which demands reduced energy consumption and CO2 production, such buildings are recognised to be a particular challenge in terms of both their poor energy performance, but also the limitations on improvement measures that do not have a detrimental affect on their form and appearance. As a result interventions that improve performance tend to less mainstream and it is therefore import to assess the effectiveness of these. This paper describes the findings of a post occupancy evaluation that examined the user satisfaction and energy performance of a recently completed (2008) adaptive rehabilitation project of a listed 19th Century sandstone tenement block in Edinburgh city centre. The project incorporates low carbon technologies and high thermal performance into an existing and historic structure, including internal insulation, a ground source heat pump with underfloor heating, sunspaces and MVHR, which are intended to reduce energy consumption whilst maintaining the built form and appearance. The paper discusses key outcomes of this performance evaluation, which identified some problems occurring with systems and users interaction with these, leading to incidences of poor environmental quality and increased energy use. The paper concludes by discussing limited improvements which could be made to this structure and future design considerations that could improve performnce.

Overheating in Scotland: contributing factors in occupied homes

ABSTRACT There is growing awareness of the overheating risks in new-build properties in the UK. However, this tends to be considered a problem principally for the southern regions in the UK, only becoming a serious issue in the north of England in the medium-term and in the long-term for Scotland. This notion tends to be largely predicated upon climate change predictions, differences in latitude and summer air temperatures. This paper describes the results from Building Performance Evaluation (BPE) studies over a two-year period from 26 occupied new-build homes across Scotland which demonstrated incidences of overheating. Results suggest that low-energy buildings are susceptible to overheating despite northerly latitudes, with 54% of houses studied overheating for more than six months annually, and 27% of homes overheating for less than 10% of the year. Evidence indicated that commonly used prediction tools do not appear to anticipate overheating adequately. This paper maps common overheating causes due to design and the role of occupants, identifying the risks due to the regulatory system, prediction and procurement processes, and design and construction. A common finding was that design and occupancy factors appear to have a greater impact on overheating more than location and climatic factors.

Adapting the Scottish tenement to twenty‐first century standards

Purpose – The stone tenement is perhaps the most iconic type of housing in Scotland and to a large extent defines the built environment of its major cities and towns. However in the context of the climate change agenda which demands reduced energy consumption and CO2 production, such buildings are recognised to be a particular challenge in terms of both their poor energy performance, but also the limitations on improvement measures that do not have a detrimental affect on their form and appearance. As a result interventions that improve performance tend to less mainstream and it is therefore import to assess the effectiveness of these, and this was the purpose of the research.Design/methodology/approach – This paper describes the findings of a post occupancy evaluation that examined the user satisfaction and energy performance of a recently completed (2008) adaptive rehabilitation project of a listed 19th Century sandstone tenement block in Edinburgh city centre. the project undertook a short intensive mo...The stone tenement is perhaps the most iconic type of housing in Scotland and to a large extent defines the built environment of its major cities and towns. However in the context of the climate change agenda which demands reduced energy consumption and CO2 production, such buildings are recognised to be a particular challenge in terms of both their poor energy performance, but also the limitations on improvement measures that do not have a detrimental affect on their form and appearance. As a result interventions that improve performance tend to less mainstream and it is therefore import to assess the effectiveness of these. This paper describes the findings of a post occupancy evaluation that examined the user satisfaction and energy performance of a recently completed (2008) adaptive rehabilitation project of a listed 19th Century sandstone tenement block in Edinburgh city centre. The project incorporates low carbon technologies and high thermal performance into an existing and historic structure, including internal insulation, a ground source heat pump with underfloor heating, sunspaces and MVHR, which are intended to reduce energy consumption whilst maintaining the built form and appearance. The paper discusses key outcomes of this performance evaluation, which identified some problems occurring with systems and users interaction with these, leading to incidences of poor environmental quality and increased energy use. The paper concludes by discussing limited improvements which could be made to this structure and future design considerations that could improve performnce.

An Investigation of Indoor Air Quality in UK Passivhaus Dwellings

The adoption of the German Passivhaus Standard in the UK has grown rapidly in recent years. Stimulated by the shift towards energy efficient design and rising fuel costs, the concept is perceived as a potential means of meeting energy and carbon targets through an established, reliable methodology. However the performance of the Standard in terms of adequate indoor air quality and thermal comfort in a UK climate remains under-researched. This paper describes the use of the Passivhaus Standard in a UK context, and its potential implications on indoor environmental quality. A case study is presented, which included indoor air quality measurements, occupant diary, building survey and occupant interviews in a Passivhaus social housing project in Northern Ireland. The study found issues with indoor air quality, the use and maintenance of Mechanical Ventilation with Heat Recovery (MVHR) systems, lack of occupant knowledge and the perception of overheating in the case study dwellings. The findings provide a much needed insight into the indoor environmental quality in homes designed to the Passivhaus standard; which can be disseminated to aid the development of an effective sustainable building design that is both appropriate to localised climatic conditions and also sensitive to the health of building occupants.

Building Performance Evaluation

This chapter will include an introduction to the context of the performance of buildings use. These include changing energy and environmental targets and the development of new designs, materials and technologies to meet these targets. The question that emerges is, are these successful? Are the targets being met and if not why not? And are there related effects on performance - do improvements in one area lead to deficiencies in others? In effect, the construction industry is conducting a series of experiments and it is important that we go back and check the results, and more importantly, learn from these. However, this type of activity is not standard practice in the construction industry. This chapter describes a series of projects that have developed and undertaken building performance evaluation (BPE). These include the development of tools, examples of BPE projects, and case studies of the type of insights that can be gained from such projects; and will conclude with a summary how these can inform both clients and designers.

Mainstreaming building performance evaluation for the benefit of users

The built environment touches the lives of almost every citizen; buildings are where we live, work, learn and play. However, they are also major contributors to energy and resource consumption, pollution and global warming. Beginning with the fuel crisis of the 1970s, but accelerating with the emerging threats of climate change, improved regulations have attempted to address these issues. This has led to changes in building construction and the adoption of new technologies. In most other industries, research and development is inextricably linked to detailed review and analysis. It might therefore seem obvious to any impartial observer that understanding how these buildings perform must be a critical dimension to their design. However, construction has its roots in a custom and practice model and, consequently, the final product is very rarely systematically or robustly evaluated.