Grainne McGill

A comparison of the estimated natural ventilation rates of four solid wall houses with the measured ventilation rates and the implications for low-energy retrofits

To reduce energy consumption and carbon dioxide emissions in existing houses in heating-dominated climates, there is a drive to reduce ventilation heat loss by tightening the building envelope. Energy-efficient domestic retrofits, which neglect ventilation requirements or assume without enquiry that adequate ventilation rates have been met, have the potential to impact negatively on the health and well-being of occupants by creating unhealthy indoor environments. The natural ventilation rates of UK dwellings created by building envelope air leakage is commonly estimated by applying a rule-of-thumb to the air flow required to create a pressure differential across a building envelope of 50 Pa using a fan pressurisation technique. To analyse the appropriateness of the rule, a tracer gas concentration decay technique was used on four Victorian solid wall houses to ascertain their natural ventilation rates created by building envelope air leakage. Results indicate that applying the rule overestimated the natural ventilation rates of the four houses tested. These findings have the potential to impact on retrofit ventilation strategies for existing houses.

Indoor air-quality investigation in code for sustainable homes and passivhaus dwellings

Purpose – Energy efficient building design strategies are growing in popularity, promoted through increased awareness of climate change, rising energy prices, global consciousness and a demand for energy security. To aid this design process, assessment tools such as Code for Sustainable Homes (CSHs) and Passivhaus were introduced in the UK. However, it is suggested that these tools prioritise energy efficiency over occupant health through a fundamental lack of attention to indoor air quality (IAQ). The purpose of this paper is to investigate IAQ in selected dwellings built using CSHs level 6, level 3 and Passivhaus homes in the UK. Design/methodology/approach – Using a case study approach, the investigation consisted of IAQ measurements during summer and winter months, occupant diaries and occupant interviews. Findings – The results from the IAQ measurements show the recommended maximum level of 1,000 ppm was breached in all three Code 6 and two Code 3 homes, with levels slightly below this limit in the t...

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.

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.

Effective indoor air quality for energy-efficient homes: a comparison of UK rating systems

The use of sustainable assessment methods in the UK is on the rise, anticipating the future regulatory trajectory towards zero carbon by 2016. The indisputable influence of sustainable rating tools on UK building regulations conveys the importance of evaluating their effectiveness in achieving true sustainable design, without adversely effecting human health and well-being. This paper reviews indoor air-quality (IAQ) issues addressed by UK sustainable assessment tools, and the potential trade-offs between building energy conservation and IAQ. The barriers to effective adoption of IAQ strategies are investigated, including recommendations, suggestions, and future research needs. The review identified a fundamental lack of IAQ criteria in sustainable assessment tools aimed at the residential sector. The consideration of occupants’ health and well-being should be paramount in any assessment scheme, and should not be overshadowed or obscured by the drive towards energy efficiency. A balance is essential.

Indoor air quality and the suitability of mechanical ventilation with heat recovery (MVHR) systems in energy efficient social housing projects: perceptions of UK building professionals

The quality of indoor air in energy efficient buildings is a significantly important yet under-researched area, particularly in a social housing context. This study investigated perceptions of UK building professionals regarding the effect of energy efficient design strategies on indoor air quality. In-depth interviews were conducted with building professionals of four recently completed UK energy efficient social housing projects. The interviews explored perceptions of the importance of indoor air quality consideration during the design process, the impact of energy efficient design strategies on indoor air and the application of Mechanical Ventilation with Heat Recovery (MVHR) systems in a social housing context.The results suggest a significant lack of attention to indoor air quality in energy efficient social housing projects; attributed to a lack of knowledge, perceived costs associated with indoor air quality strategies, focus on energy efficiency goals and a fundamental lack of motivation. Furtherm...

Place, time and architecture: the growth of new traditions

Space, Time and Architecture is intended for those who are alarmed by the present state of our culture and anxious to find a way out of the apparent chaos of its contradictory tendencies.So wrote t...

Building performance and end-user interaction in passive solar and low energy housing developments in Scotland

ABSTRACT In the UK housing sector, changes to building regulations have raised standards for fabric performance, bringing about a demand for affordable, low energy housing. Housing Associations have been at the forefront of adopting these measures, but as owners of long term rented stock it is important for them to understand and evaluate the performance of both ‘as-built’ and ‘as-occupied’ dwellings. This paper describes a detailed evaluation of three new-build social housing demonstration projects located in Glasgow (Scotland). The study included occupant surveys in each scheme, fabric testing and detailed monitoring of environmental conditions, energy consumption, and evaluation of occupancy behaviours in eight dwellings. A particular focus of this paper is the ventilation performance as the homes are ventilated differently using natural, mechanical extract and mechanical heat recovery methods. The results showed a wide discrepancy of energy consumption and poor levels of ventilation, particularly in bedrooms. Causes of this included the design and installation of the ventilation provision but occupant interaction with the systems was also a significant factor. Two sites included sun-spaces that, despite having good potential for preheat ventilation and drying spaces, were underperforming. The study highlights significant impacts of the complex interactions between heating and ventilation systems, and the apparent need for more effective ventilation strategies and systems in bedroom spaces, but also improved strategies for end-user understanding of, and interaction with, both mechanical systems and natural ventilation opportunities. The papers aims to provide robust and credible evidence on which to base critical regulatory and design decisions on the most effective means of ventilating low carbon social housing in Britain.

An investigation of indoor air quality, thermal comfort and sick building syndrome symptoms in UK energy efficient homes

Purpose – Concern of the deterioration of indoor environmental quality as a result of energy efficient building design strategies is growing. Apprehensions of the effect of airtight, super insulated envelopes, the reduction of infiltration, and the reliance on mechanical systems to provide adequate ventilation (air supply) is promoting emerging new research in this field. The purpose of this paper is to present the results of an indoor air quality (IAQ) and thermal comfort investigation in UK energy efficient homes, through a case study investigation. Design/methodology/approach – The case study dwellings consisted of a row of six new-build homes which utilize mechanical ventilation with heat recovery (MVHR) systems, are built to an average airtightness of 2m3/m2/hr at 50 Pascal’s, and constructed without a central heating system. Physical IAQ measurements and occupant interviews were conducted during the summer and winter months over a 24-hour period, to gain information on occupant activities, perceptio...

Effectiveness of Sustainable Assessment Methods in Achieving High Indoor Air Quality in the UK

The use of sustainable assessment methods in the UK is on the rise, emulating the future regulatory trajectory towards zero carbon by 2016. The indisputable influence of sustainable rating tools on UK building regulations conveys the importance of evaluating their effectiveness in achieving true sustainable design, without adversely effecting human health and wellbeing. This paper reviews the potential trade-offs between human and ecological health in sustainable building design, particularly between building energy conservation and indoor air quality. The barriers to effective adoption of indoor air quality strategies in sustainable assessment tools are investigated, including recommendations, suggestions and future research needs. The consideration of occupants’ health and wellbeing should be paramount in any sustainability assessment method, particularly indoor air quality, thus should not be overshadowed or obscured by the drive towards energy efficiency. A balance is essential.