# Scottish Passive House: Insights into Environmental Conditions in Monitored Passive Houses
## 5 Discussion
### Thermal Comfort  
The BPE study identified significant fluctuations in internal space temperatures. This affected the high and low end of the comfort temperature scale, both conditions having the potential to negatively affect the thermal comfort and health and wellbeing of the occupants. Thermal comfort is an important factor in a society where people spend over 95% of their time indoors [55]. The UK Government's  
Figure 12: Dwellings by room: Absolute Humidity (AH), annual percentage of time. Housing Health and Safety Rating System (HHSRS) states that temperatures exceeding 25 \({}^{\circ}\)C may increase cardiovascular strain and trauma [56] with severe effects such as heat exhaustion, mental health issues and heat stroke which can be fatal [32] for vulnerable occupants, including those who are infants, elderly and the obese [57]. As houses become more airtight there is an increased need to actively maintain thermal environments to provide comfort. High temperatures may be a function of heat gains (active heating or solar and incidental gains), an inability to remove heat (insufficient ventilation) or poor design. With reduced ventilation provision it is difficult to rapidly reject heat, this was found to have influenced the behaviour of the occupants participating in the study. For example, one household disabled the solar thermal system during the summer months in an effort to decrease internal temperature in the first floor bedrooms. It was later found that none of the hot water pipework was insulated and the associated heat gains were significant contributors to the heat accumulation. This also identifies a need for a cultural shift--it is a common expectation, arising from experiences with cold, expensive to heat dwellings, that in a domestic environment any heat is considered good heat. An example of this is that in Site A the hot water pipework was not insulated by the installer. This has previously been the cultural norm in less well sealed houses in Scotland due to higher infiltration rates having capacity to dissipate the heat. This identifies a need for more education of designers and tradespeople who design and install systems within thermally efficient envelopes. [PERSON] _et al._[24] found that the density and overcrowding of social housing flats built to the Passive House standard exacerbated the risk of overheating. This is of particular importance as many people in social housing are vulnerable or in poor health, and the increased use of Passive House in this sector would help reduce utility bills [24], but could potentially be harmful if thermal comfort cannot be achieved. However, this study suggests that even with a modest occupancy level, overheating may still arise. The bedroom temperatures in Site A dwellings was found to be higher than the ground floor rooms, which has consistencies with findings for lightweight timber construction by [PERSON] _et al._ (2010) and [PERSON] (2012) [30; 32]. The dwellings in Site A have a lower ceiling height than Site B dwelling and do not have high level openable windows above staircases. In Site B, where the first floor bedrooms were cooler than the ground floor, the design included high level openings to assist \"purge\" ventilation, and vaulted ceilings throughout the first floor, which can allow thermal stratification. Simple passive design approaches, such as this and external shading can help to reduce internal temperatures. Clearly, occupant behaviour has been demonstrated to have a significant impact on temperature variation and overheating [24] (p. 230). In all of the dwellings in this study, none of the occupants fully understood how to operate their systems and further assistance from their landlords was required for an extended period, which suggests that overheating might be mitigated by better handover procedures to educate occupants as to how to operate their homes. Among the outcomes of this study was the development and distribution of \"Quick Start Guides\" which were specific to each house type and their controls systems.