LOCALISED TEMPERATURE DIFFERENCES AROUND THE ROOM

In Section 5.2, the differences in temperatures from temperature loggers placed at different heights was seen to be an identifiable pattern. This section will use the temperature measurements from approximately the same height from around the living room in the Palmerston North house to see if there are additional sources of temperature variation within the room and look to see if these variations can be explained.

Table 5.12 gives the difference in the mean temperatures from each of the two temperature arrays located in the northwest and southwest corners of the room. It appears that the northwest array is approximately 0.3°C cooler than the array in the Southwest corner.

Table 5.12 Difference between temperature array in northwest corner and the temperature array in the southwest corner

Height (m) Temperature Difference (°C)

0.4 -0.24

0.9 -0.47

1.4 -0.35

Figure 5.29 and Figure 5.30 show floor plans of the living room annotated with the difference in temperature between the logger shown and the logger of approximate corresponding height in the southwest array (T3 (0.9 m) for Figure 5.29 and T6 (1.9 m) for Figure 5.30).

Figure 5.29 gives the temperature differences for loggers at a height of 0.9 m and shows that the temperature of the southwest corner appears to be warmer than the northwest corner or the east wall. Both the north and east walls are external walls so temperatures near these walls can be expected to be lower. The southwest corner also could also be warmer due to the electric hot water cylinder and the refrigerator-freezer being nearby but separated by internal walls.

Figure 5.30 again shows the north and east walls are cooler than the other sensors around the room as is TT26976 on the west wall. The southwest array, centre of room temperature (T14), and T7 are similar in temperature but T8 is higher and T13 is lower in Temperature. The logger T8 is positioned within the wall unit above a stereo unit and other electrical equipment. A refrigerator-

freezer is also positioned nearby behind the southern wall. Heat generated from appliances can be appreciable and the warmer temperatures seen by T8 may be due to this heat flow. The temperatures reported by the T13 logger are colder. This may be due to the T13 logger being positioned on a glass-backed shelf giving a path of low thermal resistance to the colder room to the south.

The local variations in the temperature within the room appear to have specific causes, such as proximity to heat sources (such as appliances), or pathways of lower thermal resistance (near to exterior walls or glass backed shelves).

It is useful to review other experiences of localised temperature differences. Figure 5.31 shows data from house W26 from the HEEP detailed temperature sample. Figure 5.31 shows three Lounge temperatures and the operation of the television set are shown over 2½ days. The temperature logger ‘TempTfrc’ was located near t he television whereas ‘TempTfra’ and ‘TempTfrb’ were located on the other side of the room.

Lounge Temperatures and TV Use for W26

15 17 19 21 23 25 27 29 31 33 24/01/1998 25/01/1998 26/01/1998 cvb Te m p e ra tu re (° C ) 0 10 20 30 40 50 60 70 80 90 100 TV (W )

TempTfra TempTfrb TempTfrc TvEfra

Figure 5.31 Monitored lounge temperatures (‘TempTfra’, ‘TempTfrb’ and ‘TempTfrc’) and TV usage (‘TVEfra’) for the HEEP detailed temperature sample house W26.

The anomalous elevated temperatures reported by ‘TempTfrc’ (when compared with ‘TempTfra’ and ‘TempTfrb’) coincide with the use of the TV set so when the TV is operating it is also heating the temperature logger ‘TempTfrc’.

In Section 3.2 it was seen that a temperature logger placed too close to lights reported elevated temperatures when the light was on. This may be due to the heat from the light or the increased radiant temperature near the light. Section 3.4 stated that the temperature loggers also response to the radiant temperatures so in addition to nearby electrical lighting, other strong radiant heat sources such as solar radiation and high temperature radiant heaters (electric radiant heaters, radiant gas heaters, portable LPG heaters, open fires) should be avoided.

Another source of heat flow is due to air movement within the room. Loggers should not be placed in positions where the air movement is higher than for the rest of the room (near operable

windows, doorways, fans or ventilation systems). Draughts also occur close to edges so loggers should be placed away from the ceiling or floor and, where possible, also away from walls. Lyberg (1993) also provides useful guidance on the placement of temperature loggers.

How these causes affect the temperatures is hard to quantify. The large number of possible influencers and unknown size of each affect makes quantitative analysis difficult. Localised temperature differences may be a non-predictive source of variation and the best course of action may be to ensure that the placement of the temperature loggers minimise the local influences.