*4.2.1. Occupancy*

The first study period in February (SP1) ran from 15/02/11 at 00:00 until 27/02/11 at 23:55. In December study period two (SP2), ran from 06/12/11 at 00:00 to 15/12/11 at 23:55. Ideally both study periods would be for the same duration, however, it was determined that the se‐ lected periods (SP1 and SP2) from each study were sufficient to provide adequate data for analysis and comparison.

The February study monitored a period of non-occupancy prior to SP1 commencing. This data provides a valuable 'control' period (CP) which can be utilised to understand how the house performed in relation to IAQ when uninhabited. Although the studies were run dur‐ ing different months, they were both in the winter period of the same year. Average external temperatures during this period were 5.5 0 C in SP1 and 3.3 0 C in SP2. The studies can be compared reasonably accurately in relation to this slight inconsistency.

During study periods occupancy levels in the houses remained constant. The houses' flexi‐ ble layout resulted in sleeping arrangements varying depending on how the show home had been set up. (Table 1).


**Table 1.** Occupant Sleeping Arrangements, SP 1 & 2, House A

**Figure 1.** The Glasgow House, Ground Floor Plan

When assessing IAQ in relation to the specified Ta, RH and CO2 criteria, the maximum and minimum values recorded are of most significance as well as the subsequent range pro‐ duced. A graphical output, visually representing the continuous change in these values over time is appropriate for analysis and discussion. Mean values calculated from these indica‐ tors can sometimes be of use to give an overall representation of the data. However, this sta‐ tistic can overlook significant individual moments, diluting the importance of some data, and thus failing to give an accurate depiction of performance. Mean values may be more ap‐ propriate for other IAQ indicators, such as VOCs and plasticisers, which have constant background levels. The data collected was subject to certain variables and limitations.

The first study period in February (SP1) ran from 15/02/11 at 00:00 until 27/02/11 at 23:55. In December study period two (SP2), ran from 06/12/11 at 00:00 to 15/12/11 at 23:55. Ideally both study periods would be for the same duration, however, it was determined that the se‐

**4.2. Data review**

146 Sustainable Energy - Recent Studies

*4.2.1. Occupancy*

When assessing the results it should be noted that in House A, Bedroom 3 was set up as a study/office and was not used for sleeping. As a consequence, the occupancy of House A, Bedroom 4 was double that of House B. Data collected from House A, Bedroom 3 is still rel‐ evant, although the results will not warrant accurate comparison with House B, Bedroom 3. The data can be viewed to see how the room performs when uninhabited, similar to the con‐ trol period mentioned previously. House A, Bedroom 3 can be compared between the two study periods, however. It is worth mentioning that each occupant will not have spent the same amount of time in their bedroom and sleeping patterns will have varied. Similarly, room occupancy level throughout the house may have varied from time to time, depending on occupant activities and interaction. High occupancy room levels ≥ 3 inhabitants.

When evaluating the data it is essential to consider each bedrooms qualities, in order to make fair comparisons. (Table 2).

The room on the 2nd floor, in the attic space, is the largest of the bedrooms. Bedroom 3 is the smallest. Bedroom sizes vary slightly between the two houses. This is due to the construc‐ tion types, which alter the wall build up, affecting internal space a little. The houses have identical plan configurations.


Whilst this project is focused primarily on investigating CO2 levels, it is worth including the analysis of the other monitored indicators, Ta and RH. Observing several IAQ components provides a greater understanding of how the MVHR system is functioning. Over the study periods all three of the indicators contributed to unhealthy IAQ within the bedrooms. CO2

The graphical output produced, as well as the statistics calculated, shows that Bedroom Ta

lated IAQ was unsuitable for sleeping on occasions. (Table 4) Within the data, an apparent difference is visible between the SP1 and SP2 results. Although ranges are similar, SP2 bed‐ room Ta was lower than the previous study, resulting in a reduced overall Ta. House A and

**Bedrooms Max (°C) Min (°C) Range Mean (°C)** SP1 – House A 23.30 16.60 6.70 20.01 SP1 – House B 22.40 16.70 5.70 19.82 SP2 – House A 20.40 14.50 5.90 16.95 SP2 – House B 19.30 13.50 5.80 16.25

Similarly, RH failed to maintain the standard defined as 40-70%. With corresponding to Ta values, maximum RH values are within the prescribed range, but the minimum values re‐ corded fall below. This resulted in the occupants experiencing reduced IAQ during these in‐

**Bedrooms Max (%) Min (%) Range Mean (%)** SP1 – House A 59.30 31.10 28.20 43.37 SP1 – House B 67.50 32.50 35.00 43.25 SP2 – House A 56.40 35.30 21.10 43.96 SP2 – House B 61.20 36.90 24.30 45.40

There appears to be little difference in RH between SP1 and SP2. Also, House A's perform‐

C, during both studies. The houses

The Role of Building Users in Achieving Sustainable Energy Futures

C range. The temperature re‐

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

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levels were of significant concern.

fell out with the preferred parameters, defined as 18-200

failed to sustain a constant bedroom Ta, within the optimum 20

B appear to function very similarly to one another in the studies.

*4.2.2. Air temperature data*

**Table 4.** Overall Bedroom Ta Statistics

**Table 5.** Overall Bedroom RH Statistics

ance does not differ from that of House B.

*4.2.3. Relative humidity*

tervals. (Table 5)

**Table 2.** Bedroom Information

The MVHR system was serviced and its installation altered between SP1 and SP2.The stud‐ ies had prescribed occupancy patterns to achieve specific goals and were scripted to accu‐ rately represent the airtight dwellings' IAQ performance using the MVHR system. The occupants were asked to refrain from naturally ventilating the dwellings, by opening win‐ dows and doors, and not to alter temperature thermostats. However, during SP1 windows were opened by the occupants in both House A and House B. (Table 3).


**Table 3.** Frequency of Window Opening, SP1, House A and B

The consequence of this natural ventilation will have more of an impact on the data collect‐ ed in House A, simply due to the greater over all duration in which the windows were open, than in House B; 43 hours compared with 4 hours, respectively. Conclusions drawn from the particular data in both houses should acknowledge these variances in terms of their effect on Ta, RH and CO2 levels within the specified rooms.

During SP2 window opening was more tightly controlled and no natural ventilation was re‐ corded, however, an occupant in House B increased the radiator thermostats in the kitchen, liv‐ ing room, utility and attic bedroom from one to four, over a period of 18.75 hours on 06/12/11. This change may have affected the data collected for House B, in particular in Bedroom 4. Any conclusions drawn from the particular data should take into account this variance.

Whilst this project is focused primarily on investigating CO2 levels, it is worth including the analysis of the other monitored indicators, Ta and RH. Observing several IAQ components provides a greater understanding of how the MVHR system is functioning. Over the study periods all three of the indicators contributed to unhealthy IAQ within the bedrooms. CO2 levels were of significant concern.
