**2. Indoor air quality**

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

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‐

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‐

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)

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.

are not applied retrospectively.

142 Sustainable Energy - Recent Studies

cations are for energy consumption and health.

gow Housing Association.

system.

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, which seeks to maximise ventilation, needs to be addressed.

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 as,

"...air which is free from pollutants that cause irritation, discomfort or ill health in the occu‐ pants." [14].

Scottish Building Standards (SBS) states that indoor air quality should not endanger the health of the inhabitants [15]. It suggests a temperature range of 18 - 21o C, relative humidity (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 time, the advised levels of ventilation should be adaptable [17].

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‐ ed and the current consensus of opinion is that levels above 1000ppm are linked to poor occupant health [21]. Where concentrations greater than 1000ppm are experienced the rate of air change is insufficient and the potential for culmination of internal pollutants is increased with an associated impact on occupant health. Examples within domestic contexts include vol‐ atile organic compounds (VOC), which act as allergens and respiratory and dermal irritants [22].With low air change rates there is also a well-defined risk of interior moisture vapour build up which brings with it its own set of health implications. Vapour pressures over 1.13kPa have been identified as promoting the growth of dust mite populations [23] which have, in turn, have been found to have a causal relationship with development of asthma in susceptible children [24]. With high vapour pressures there is also an associated risk of fugal growth and an increase in the levels of fungal spores, microbial bodies and other pathogens which can be detrimental to the health, particularly to the ever increasing atopic portion of the population. In addition to this, increased relative humidity has also been found to increase health impact from non-biological aerosols as it increases the rate of off gassing of water-soluble chemicals such as formaldehyde [25].

to-day activities. This included the documentation of house occupancy periods, personal sanitary routines, and the use of individual electrical equipment. Cooking periods and kettle use were recorded separately, as well as instances when the boost switch was used on the extract for the MVHR system, usually in association with showering or food preparation. Room occupancy levels and window opening was also documented. Participation in post occupancy evaluation (POE) questionnaires allowed for the occupants qualitative and func‐

The Role of Building Users in Achieving Sustainable Energy Futures

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

145

In Gilmores Close, due to the more vulnerable nature of the occupants (a high proportion of which have special needs), a semi-structured interview was conducted with residents and office users to query patterns of occupancy, user behaviour and comfort. This was supple‐

The two semi detached houses were built in 2010 by City Building (CB) in partnership with the GHA. They were designed to provide comfortable and flexible living for low income families with an aim of costing no more than £100 per year to heat. The houses are of similar layout and consist of a porch, kitchen/dining/living area, a utility room/WC, four bedrooms,

The design incorporated high levels of thermal efficiency using a Thermoplan clay block with external insulation, highly insulated roof cassettes and high performance windows, thermal mass, airtight construction (0.4 ach), sunspaces, solar thermal hot water collectors, mechanical ventilation heat recovery, low energy lighting and high efficiency appliances (House A). The comparison house is identical house except the clay block is replaced with a more conventional highly insulated timber frame system which is the standard form of con‐

A series of scenarios were proposed to examine how these houses performed in use with ac‐ tual occupants. Findings from two separate periods of BPE, in February and December 2011 are described here. In both cases four occupants inhabited each dwelling. They were to sim‐ ulate an average family living pattern and were given prescribed scripts on occupancy.

Heating is by a high efficiency gas boiler and radiators. Hot water heating is supplemented by the use of a solar hot water system. Ventilation is by a MVHR system, extracting air from the kitchen and bathrooms spaces and supplying a balanced flow of air to the living room and bed‐ rooms. The temperature of the house was pre-set using the main thermostat and by the indi‐ vidual thermostats on the radiators in each room. The MVHR system was inspected visually and the filters changed if necessary. Electricity and gas meter readings were made at the start

and end of the monitoring process in each dwelling to record energy consumption.

mented by surveyors observations, photographs and thermographic imaging

tional responses towards the houses to be gathered.

**4. Case study 1: The Glasgow house**

**4.1. Construction**

a bathroom and garden.

struction used by City Building.

In both these case studies a key component to address the issue of ventilation and energy use was the inclusion of Mechanical Ventilation Heat Recovery Systems (MVHR). The prin‐ ciple of these systems is that poor quality, but relatively high temperature internal air is me‐ chanically extract from spaces in the dwelling, typically spaces which contain 'problem' air such as high moisture content or smells from kitchen and bathrooms. This air is passed through a heat exchanger during which colder fresh air from the outside is warmed by the recovered heat before being delivered to the dwelling. In theory should satisfy the needs of both energy conservation and IAQ to produce a sustainable solution. Accordingly the dis‐ cussion below makes particular reference to the performance of these systems.
