CHAPTER EIGHT DAMPNESS, CONDENSATION AND MOULD
Introduction
8.1 While not a primary objective of the CHP, tackling the problems of dampness, condensation, and mould in Scottish housing has been a major priority in Scotland for well over a decade. The general solution for tackling condensation and mould is to increase the heating used within the home, to increase the insulation of the dwelling, and to improve the ventilation. Thus, installing central heating and insulation under the CHP improvements should help reduce the extent of dampness and mould growth problems where these problems are condensation-related.
Dampness and Condensation
8.2 Both the household questionnaire and energy audit survey sought information on the presence and extent of dampness and condensation in each dwelling surveyed. Information was collected on a room by room basis through questioning of the householders for the situation before the CHP improvements, and through questioning of the householders and visual inspections of the individual rooms by the surveyors regarding the situation after the CHP improvements. Given the difficulties associated with identifying the actual cause of the problem, no distinction was made by the surveyors on whether the problem was condensation or some other form of dampness.
8.3 The presence of condensation and dampness in each room was scored on a 3-point scale:
- small spots on the walls or the ceiling or misting of window surfaces;
- hand-sized patches on the walls or the ceilings or streaming windows and minor pooling of water of window sills;
- large patches on walls or the ceilings, or the formation of large pools of water on the sills that risked overflowing onto the wall.
These room scores were then aggregated for the whole house and an overall average score for each dwelling produced by dividing the aggregate score by the number of rooms within the dwelling. The findings are presented below on an individual room basis, and for the overall dwelling.
8.4 From combining the information from the questionnaire and the energy audit survey, the majority of all of the individual rooms were recorded as being free of dampness and condensation for the periods before and after the CHP improvements (see Table 8.1). Subsequent to the CHP improvements, there was a reduction in the number of rooms where dampness or condensation was present, as well as a reduction in the overall severity of the condensation and dampness problem.
Table 8.1 Incidence and Severity of Dampness or Condensation
Room | Before CHP improvements | After CHP improvements |
|---|
%of dampness and condensation-free rooms / dwellings | Average severity of dampness and condensation (all dwellings) | Average severity of dampness and condensation (only rooms with problem) | % of dampness and condensation-free dwellings | Average severity of dampness and condensation (all dwellings) | Average severity of dampness and condensation (only rooms with problem) |
|---|
Lounge (n = 1385) | 93.6% | 0.11 | 1.64 (n = 89) | 98.7% | 0.02 | 1.19 (n = 18) |
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Main Bedroom (n = 1380) | 88.8% | 0.19 | 1.79 (n = 154) | 97.7% | 0.03 | 1.23 (n = 32) |
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Second Bedroom (n = 1079) | 85.2% | 0.26 | 1.77 (n = 160) | 96.8% | 0.04 | 1.39 (n = 35) |
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Third Bedroom (n = 456) | 80.9% | 0.33 | 1.74 (n = 74) | 96.5% | 0.04 | 1.19 (n = 16) |
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Hall (n = 1380) | 94.6% | 0.09 | 1.69 (n = 74) | 99.0% | 0.01 | 1.27 (n = 13) |
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Kitchen (n = 1349) | 89.4% | 0.19 | 1.76 (n = 143) | 97.5% | 0.03 | 1.19 (n = 34) |
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Bathroom (n = 1385) | 86.4% | 0.24 | 1.80 (n = 188) | 96.6% | 0.05 | 1.36 (n = 47) |
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Overall House (n = 1385) | 74.9% | 0.18 | 0.71 (n = 348) | 93.5% | 0.03 | 0.46 (n = 90) |
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8.5 The relationship between use of heating and the levels of condensation and dampness appear to be reaffirmed by the results: the two worst scoring rooms in terms of the severity of the condensation and dampness problem before the CHP improvements were the bathroom and the third bedroom (where it was present). These were also the least heated rooms within the dwellings surveyed (see Table 5.6). Generally, the use of more heating appears to have had a considerable effect on reducing the incidence and severity of condensation and dampness problems in the home. Where condensation and dampness problems had reportedly cleared completely, or the severity reduced, more heating was used in:
- 80.0% of the main bedrooms;
- 68.0% of the second bedrooms;
- 67.9% of the third bedrooms;
- 81.4% of the hallways;
- 61.9% of the kitchens (but not all kitchens received heating under the CHP);
- 56.8% of the bathrooms.
8.6 Overall, in 66.3% of all of the rooms where condensation or dampness problems had reportedly cleared completely, and in 77.8% of the rooms where the severity of the problem had reduced, more heating was being used after the CHP improvements than before.
8.7 When these room results were aggregated and averaged across the whole house, the overall incidence and severity of condensation and dampness declined subsequent to the CHP improvements. The number of completely condensation and damp free homes increased from 74.9% prior to the CHP improvements to 93.5% afterwards (see Table 8.2). The average overall severity of condensation and dampness in the home fell from 0.10 on the 3-point scale before to 0.02 after the CHP improvements, while the severity within the rooms affected fell from 0.68 to 0.42 on average on the 3-point scale.
Table 8.2: Average severity of dampness or condensation: Overall dwelling
Severity of condensation (average on 3-point scale) | % of Dwellings before CHP improvements | % of Dwellings after CHP improvements |
|---|
No condensation | 74.9% | 93.5% |
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Up to 1 | 21.8% | 6.4% |
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Up to 2 | 2.5% | 0.1% |
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Up to 3 | 0.8% | 0% |
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8.8 Condensation and dampness was not reduced or eradicated in all dwellings after the CHP improvements. Many causes of dampness have nothing to do with inadequate heating or poor insulation. There were also 15 instances (that is, affecting less than 0.2% of all the rooms) where a room was reported as having a problem with condensation after the CHP improvements, where there was none previously.
Presence of Mould in the Home
8.9 The presence of mould in the home was assessed in a similar way to the presence of condensation or dampness: through the questioning of the occupants and the visual inspection of the individual rooms by the surveyor. Again, the extent and severity of the mould was scored on a 3-point scale for both before and after the CHP improvements:
- small spots on the walls or the ceiling;
- hand-sized patches on the walls or the ceilings;
- large patches on walls or the ceilings.
8.10 The overwhelming majority of all the individual rooms were recorded as being mould-free for the periods before and after the CHP improvements (see Table 8.3). After the CHP improvements, there is a reduction in the number of rooms where mould is present, as well as a decline in the overall severity of the extent of mould.
Table 8.3: Incidence and Severity of Mould in Home
Room | Before CHP improvements | After CHP improvements |
|---|
% of mould-free dwellings | Average severity of mould (all dwellings) | Average severity of mould (only rooms with problem) | % of mould-free dwellings | Average severity of mould (all dwellings) | Average severity of mould (only rooms with problem) |
|---|
Lounge (n = 1385) | 97.7% | 0.04 | 1.88 (n = 32) | 99.6% | 0.004 | 1.00 (n = 5) |
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Main Bedroom (n = 1380) | 94.9% | 0.10 | 2.00 (n = 71) | 99.1% | 0.03 | 1.08 (n = 32) |
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Second Bedroom (n = 1079) | 92.9% | 0.15 | 2.04 (n = 77) | 98.5% | 0.02 | 1.50 (n = 16) |
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Third Bedroom (n = 456) | 89.7% | 0.21 | 2.09 (n = 47) | 97.4% | 0.04 | 1.17 (n = 12) |
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Hall (n = 1380) | 98.5% | 0.03 | 2.24 (n = 21) | 99.4% | 0.01 | 1.40 (n = 5) |
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Kitchen (n = 1349) | 93.8% | 0.13 | 2.12 (n = 84) | 98.6% | 0.02 | 1.53 (n = 19) |
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Bathroom (n = 1385) | 92.8% | 0.14 | 1.98 (n = 100) | 98.1% | 0.03 | 1.44 (n = 26) |
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Overall House (n = 1385) | 85.3% | 0.10 | 0.68 (n = 204) | 96.3% | 0.02 | 0.42 (n = 51) |
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8.11 Although the mould problem affects fewer dwellings overall than do the problems of dampness and condensation, the severity within the rooms affected by the mould problem was higher that condensation and dampness severity.
8.12 Again, the use of more heating appears to have had a considerable effect on reducing both the incidence and severity of mould problems in the home. In those rooms that were mould-free subsequent to the CHP improvements, or where the problem was less severe, more heating was used in:
- 79.7% of the main bedrooms;
- 60.0% of the second bedrooms;
- 60.5% of the third bedrooms;
- 75% of the hallways;
- 49.3% of the kitchens (as noted above, heating was not always provided to the kitchen under the CHP);
- 85.4% of the bathrooms.
8.13 Overall, the mould problems reportedly cleared completely in 67.8% of the rooms so affected subsequent to the CHP improvements where more heating was used. The severity of the mould problem was reduced in 73.1% of the rooms where more heating was used.
8.14 When these room results are aggregated and averaged across the whole house, the overall incidence and severity of mould has decreased subsequent to the CHP improvements. The number of completely mould-free homes increased from 85.3% of dwellings prior to the CHP improvements to 96.3% afterwards (see Table 8.4). The average overall severity of mould within the dwelling fell from 0.10 on the 3-point scale before, to 0.02 after the CHP improvements; while the mean room severity fell from 0.68 to 0.42 on average on the 3-point scale.
Table 8.4: Average severity of mould: overall dwelling
Severity of mould (average on 3-point scale) | % of Dwellings before CHP improvements | % of Dwellings after CHP improvements |
|---|
No Mould | 85.3% | 96.3% |
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Up to 1 | 12.5% | 3.6% |
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Up to 2 | 1.7% | 0.1% |
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Up to 3 | 0.6% | 0% |
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8.15 The mould problem was not reduced or eradicated in all dwellings after the CHP improvements. As with dampness, the cause of the mould problem may be unrelated to inadequate heating or poor insulation. There were also 4 instances (that is, affecting less than 0.05% of all the rooms) where a room was reported as having a problem with mould after the CHP improvements, where there was none previously.
Overall comment on Chapter Eight
8.16 Condensation and dampness problems were not a significant problem overall within the dwellings that have benefited from the CHP improvements. Though for the individual dwellings so affected, the problem ranged from affecting a single room, through to affecting the whole house. Increased use of heating, improved insulation, and extra ventilation are advocated as the solutions to tackling condensation and mould problems in homes. The CHP improvements addressed two of these solutions directly, and the dwellings with dampness, condensation and mould problems appeared to reap the benefits in terms of reducing both the number of dwellings suffering from condensation or dampness problems and mould problems, and the severity of these problems where they continue to persist.