**1. Introduction**

In the drive to provide a sustainable energy strategy the reduction of energy use by build‐ ings is a crucial component as they provide the majority of energy use and carbon emis‐ sions. In an attempt to mitigate the damaging effects of greenhouse gas emissions, international governance has legislated for the reduction of energy use and CO2 emissions. In Scotland (the setting for this research) the Government has identified target reductions in domestic regulated energy use of 30% by 2010 and 60% by 2013 (compared to 2007 technical standards) and the ambition of whole life zero carbon by 2030 [1]. A low carbon economy is now a strategic priority for the Scottish Government. As domestic energy use represents 30% of total national energy use [2] there can be little doubt over the role this sector has to play in helping to achieve the targeted reductions. Whilst for new buildings this may be ad‐ dressed through building standards, a more pressing problem is that an estimated 70% of the stock currently in existence will still be standing and in use by 2050, and much of this stock has a very poor performance [3]. Therefore the role that existing dwellings will have to play in helping to meet these ambitious targets cannot be underestimated.

The primary mechanism to affect change has been improved building regulations, for which compliance is achieved at design stages. Although standards have improved significantly in recent years, it is becoming increasingly apparent that these are not being translated into en‐ ergy savings in practice [4]). In situations where thermal improvements are made there is emerging evidence that the drive for energy reduction is resulting in other unintended nega‐ tive consequences, for example poor indoor air quality which as well as being problematic in its own right, also leads to rebound behaviours which undermine energy strategies [5].

Problems of energy consumption and carbon emissions apply to both new and existing buildings. Existing buildings are in many ways a more significant problem, in that they tend

© 2012 Sharpe; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Sharpe; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

to have very much worse energy performance; make up a much larger proportion of the stock; can have physical, economic and cultural barriers to major improvements; and are not subject to the same regulatory requirements as new building as current building standards are not applied retrospectively.

Although very different house types, built over 120 years apart, both are attempting to meet contemporary standards in terms of energy use. In the evaluation several common factors re‐ lating to ventilation and indoor air quality (IAQ) were apparent in the performance of both projects and the question that this chapter addresses is how these factors affect building occu‐

The Role of Building Users in Achieving Sustainable Energy Futures

http://dx.doi.org/10.5772/51900

143

IAQ is an important, but neglected aspect of sustainable design, which more commonly em‐ phasises energy use and carbon reduction. However, achieving good IAQ is important for a number of reasons. Firstly it is crucial for health and well-being of occupants. Secondly, it is increasingly evident that poor IAQ can lead to detrimental energy performance, for exam‐ ple, users opening window to control temperature, humidity, stuffiness and smells, even when mechanical systems are intended to address these issues. Thus the tension that exists between low energy design, which attempts to minimise ventilation loss, and good IAQ,

The majority of the world's population spends 90% of their lives indoors [8], [9]. Its quality is of recognized concern [10] and can be affected by many factors, most noticeably air temperature (Ta), as well as surface temperature (Ts), humidity and pollution levels. IAQ affects how inhab‐ itants perceive a space, to the same extent as the availability of space and light do. Through sound and well tested ventilation design a healthy living environment can be achieved.

Globally, indoor pollution has been related to respiratory illnesses [11]; has resulted in an increase in childhood asthma [12] and poor levels of IAQ have been linked with mechanical ventliation and sick building syndrome [13]. Factors that contribute to IAQ can be consid‐ ered in various ways and calculated using different indicators. Allard defines optimum IAQ

"...air which is free from pollutants that cause irritation, discomfort or ill health in the occu‐

Scottish Building Standards (SBS) states that indoor air quality should not endanger the

(RH) of below 70% as well as specifying trickle vent sizes to maintain air quality. Although clearer than the previous definition, the standards expediency is debatable, producing only the minimum levels of IAQ needed, whilst focusing on maximising energy efficiency [16]. Temperature and RH ranges are not room specific, and with indoor pollution varying over

CO2 is an appropriate indicator to measure when assessing IAQ and was used in these studies as its importance as an environmental indicator is invaluable. The concentration of CO2 is very rarely found at hazardous levels indoors, but levels of CO2 represent the presence of other con‐ taminants in the air, such as bio-effluents, which relate directly to health issues [18]. Increased levels of CO2 are indicative of occupancy and inadequate ventilation [19]. Pettenkofer first test‐ ed air for the presence of CO2 [20]; consequently Pettenkofer's Max, of 1000ppm, was establish‐

C, relative humidity

health of the inhabitants [15]. It suggests a temperature range of 18 - 21o

time, the advised levels of ventilation should be adaptable [17].

pants, their subsequent behaviour, and how this in turn affects energy consumption.

which seeks to maximise ventilation, needs to be addressed.

**2. Indoor air quality**

as,

pants." [14].

The use of Building Performance Evaluation (BPE) is a crucial tool in assessing the tangible performance of buildings, and identifying the positive and negative factors that lead to ac‐ tual consumption. The Mackintosh Environmental Architecture Research Unit (MEARU) has been at the forefront of developing and promoting forms of BPE [6] and has undertaken a range of evaluations in both new build and existing buildings. BPE includes both qualita‐ tive and quantitative methods to gather data on energy use, environmental performance and occupant behaviour and attitudes. From this is it possible to identify actual energy con‐ sumption, patterns of occupancy and behaviour, and the environmental conditions that are being achieved and from these determine process changes in design, management, procure‐ ment, construction and use that can improve building performance. The use of BPE is cru‐ cial to sustainable urban futures is as it identifies the gaps that occur between design, construction and occupancy. Wider use of BPE in the future may place more of an onus on designers to consider actual performance, as opposed to designing for regulatory compli‐ ance. It is a technique that can be applied to both new build and existing buildings.

Of these, the issues of occupancy are attracting the most interest. The potential impacts of occupant behaviour on energy consumption are significant, with some studies identifying variation in consumption by a factor of 4 and 5 times between identical dwellings [7]. Of equal importance however is the question of the impacts *on* occupants of low energy design in respect of environmental performance, especially indoor air quality, and what the impli‐ cations are for energy consumption and health.

This chapter will describe and compare two case study projects that have used BPE to inves‐ tigate performance in use, as a comparison of two very different building types. The first of these is the refurbishment of a 19th century Grade A listed tenement building in Edinburgh; the second is the 'Glasgow House' a prototype low energy housing development for Glas‐ gow Housing Association.

The former is an existing 19th century stone built tenement in Edinburgh's Grassmarket that was refurbished to a high standard, including improved fabric performance through inter‐ nal insulation and secondary double glazing, sun spaces, a ground source heat pump sup‐ plying underfloor heating, and a mechanical heat recovery ventilation system (MVHR) system.

The 'Glasgow House' is a new build project developed by Glasgow Housing Association (GHA), one of Europe's biggest landlords, as a prototype for future housing developments in the city. The design proposed a thermally heavy clay block system, with high thermal performance, glazed sun spaces, MVHR, solar thermal hot water heating; high efficiency gas boiler and low energy lighting equipment. Due to uncertainties about this type of construc‐ tion, two test houses were constructed by GHA's partner organisation, City Building one of which uses a more standard form highly insulated timber frame.

Although very different house types, built over 120 years apart, both are attempting to meet contemporary standards in terms of energy use. In the evaluation several common factors re‐ lating to ventilation and indoor air quality (IAQ) were apparent in the performance of both projects and the question that this chapter addresses is how these factors affect building occu‐ pants, their subsequent behaviour, and how this in turn affects energy consumption.
