*5.3.1. Thermal comfort*

Due to the anecdotal evidence on overheating, this was the initial focus of initial research. A review of physical data at the macro level (Table 8) confirmed that the mean and absolute maximum temperatures within all apartments (office space excluded) were - often signifi‐ cantly - beyond the accepted comfort range. The mean values confirmed the suspicions held at the project outset but did not provide any information on cause or potential solutions.


**Table 8.** Mean and absolute maximum thermal conditions over project duration

To identify this, a more focussed review was undertaken of each dwelling relative to the profile of physical parameters on a diurnal basis.

Figure 9 illustrates a typical daily example where a living space is heated to a degree of dis‐ comfort and then is rapidly cooled by the occupant behaviour of liberal window opening. This behaviour was found to be repeated throughout the development and was supported by the survey responses in which 60% of residents noted they opened windows every day throughout the year.

Recorded data from an unoccupied dwelling had shown that a relatively stable temperature profile could be maintained internally which demonstrated that despite the loss of thermal mass necessitated by insulated dry-lining and timber construction the fabric was capable of facilitating thermal comfort. Further investigation using thermal imaging provided an in‐ sight to problems of frequent overheating. Figure 11 shows the surface temperature of a typ‐ ical apartment floor at two different points in time. In the first (T1) the thermostat was set at its lowest level yet a temperature of 28.9°C was evident. Immediately after this image was taken the thermostat was turned to it's highest setting with the same image being taken one hour later (T2).

**Figure 10.** Physical parameters in Dwelling 5 living room – fluctuating thermal comfort

apartments, the hall and kitchens of five flatted dwellings and throughout one office space

Although not a longitudinal study, there are significant benefits in a short, intense period of monitoring. The relatively brief duration led to limited intrusion on the occupants, ensured continuity in data collection relative to both dwellings and occupants and allowed a fine

Due to the anecdotal evidence on overheating, this was the initial focus of initial research. A review of physical data at the macro level (Table 8) confirmed that the mean and absolute maximum temperatures within all apartments (office space excluded) were - often signifi‐ cantly - beyond the accepted comfort range. The mean values confirmed the suspicions held at the project outset but did not provide any information on cause or potential solutions.

**Room Mean Temp (oC) Comfort Temp (oC) Δ T 1 (oC) Absolute Max (oC) Δ T 2 (oC)** Living Rm 22.62 21.00 +1.62 28.00 +7.00 Kitchen 22.87 18.00 +1.87 29.10 +11.10 Hall 23.45 18.00 +5.45 31.20 +13.20

Bedroom 1 22.58 18.00 +4.58 27.20 +9.20 Bedroom 2 21.41 18.00 +3.41 26.20 +8.20

To identify this, a more focussed review was undertaken of each dwelling relative to the

Figure 9 illustrates a typical daily example where a living space is heated to a degree of dis‐ comfort and then is rapidly cooled by the occupant behaviour of liberal window opening. This behaviour was found to be repeated throughout the development and was supported by the survey responses in which 60% of residents noted they opened windows every day

Recorded data from an unoccupied dwelling had shown that a relatively stable temperature profile could be maintained internally which demonstrated that despite the loss of thermal mass necessitated by insulated dry-lining and timber construction the fabric was capable of facilitating thermal comfort. Further investigation using thermal imaging provided an in‐ sight to problems of frequent overheating. Figure 11 shows the surface temperature of a typ‐ ical apartment floor at two different points in time. In the first (T1) the thermostat was set at its lowest level yet a temperature of 28.9°C was evident. Immediately after this image was

Sun Space 21.24 40.90

**Table 8.** Mean and absolute maximum thermal conditions over project duration

profile of physical parameters on a diurnal basis.

(noting that in each case the bathrooms/ WCs were omitted).

*5.3.1. Thermal comfort*

160 Sustainable Energy - Recent Studies

throughout the year.

granularity, which helped to identify specific events within the flats.

The level of the initial reading suggested that the control of the heating system was ineffec‐ tive. This was confirmed by the lack of response over the subsequent sixty-minute period. Poor performance of heating controls, allied to a poor user interface, were identified as fac‐ tors that consistently resulted in the creation of sustained internal temperatures exceeding the comfort range. In addition to this, the lack of thermal mass in the structure, an outcome of the approach to thermal upgrade of the historic fabric, results in high rates of heat gain and loss; a process which is difficult for residents to stabilise once the cycle of window open‐ ing has commenced. Ultimately, having windows open when heating is on leads to an in‐ crease in the energy required for space heating and undermines the thermal efficiency of the building. This also provides an explanation for the disparity in predicted and measured en‐ ergy loads for space and water heating.

With the potential health impacts, the importance of good IAQ cannot be a secondary con‐ cern and it must not be undermined by attempts to improve thermal efficiency and air tight‐ ness. Not withstanding this position, the level at which poor air quality is perceptible has the potential to cause occupants to manually seek improved ventilation. With a CO2concen‐ tration of 1000ppm poor air quality is perceptible to humans with the stress initiated behav‐ ioural response invariably being one of window opening and the result being, as was evidenced with the poor thermal control, one of high energy loss. Instances of this were identified through in the monitoring of this project and the outcome of poor air quality is (entirely rational) behaviour that counteracts the approach to energy conservation central to

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A further issue of note in relation to the MVHR system is that of maintenance. The MVHR system contains air filters to screen for dust and particulate and the need ensure these are cleaned on a regular basis is critical to the functionality and energy consumption of the sys‐ tem. In this instance limitation on the space available has led to the placement of the unit in a location above a dropped ceiling where access for maintenance and filter replacement is

The study identified that through the refurbishment considerable improvement has been made in the thermal performance of the buildings and there should be no doubt that overall it has been successful in terms of the improvement of the flats and the maintenance of the

However, the study also found that there are some problems that lead to a reduced energy performance and some unintended negative consequences, particularly in respect of indoor air quality. These are due to some design issues, for example the fire protection measures over-riding the ventilation strategy; the desire to increase living space in the sun-spaces un‐ dermining the energy strategy (not discussed in this Chapter); the loss of thermal mass through the provision of internal insulation and lightweight sub-division; and the design in‐ tegration of elements such as the MVHR and sunspaces. There are also issues of installation, commissioning and maintenance, including the lack of proper control of the heating system,

The study identified a number of measures for improvement, both remedial measures in

Options for improvements in this development that are currently being explored include: the re-commissioning and improvement of the heating control systems; an extension of the MVHR supply ducts to deliver air directly into living spaces and bedrooms; provision of ad‐

These findings are also relevant to future developments in this building type. The original building would have had an energy strategy relying on open fires with chimneys providing significant levels of radiant and convected heat, which would engage with the thermal mass of the building. Sash and case windows, although relatively draughty by contemporary standards, provide high and low level openings, which, when combined with high ceilings give very good ventilation regimes. The literature review for this project has highlighted a

a contemporary design ethos.

physically very difficult.

cultural heritage of these buildings.

and MVHR specification and installation.

ditional control over the sunspace extract system.

these flats, but also lessons for similar developments elsewhere.
