improving comfort levels has a positive effect on the work engagement of the employees, with an increase of almost 4 %. In this study, the work engagement is assessed as the level of comfort of employees within their job. Higher work engagement levels imply that employees are less likely to change their jobs, therefore reduced employee turnover rates( due to an unsatisfactory indoor environment)( Feige et al. 2013). Increased concentrations of chemical pollution are present in today’ s interior spaces due to the high VOC and formaldehyde emissions of building materials, interior fittings, furnishings and fabrics. These can cause allergic reactions, headaches, nausea itchy skin, etc., many of the symptoms that are commonly related to SBS( Singh et al. 2010). As buildings become more airtight, effective ventilation of interior spaces is essential as is proper flush out of buildings prior to occupancy( new construction, renovation etc.), to reduce toxic fumes and particulate matter within the indoor environments. Using low VOC emitting products and finishes will reduce their concentration in the indoor environment. The highest sources of VOC emissions in offices were due to the off- gassing of building materials such as‘ paints, carpets, adhesives, treated timbers and wood products’. Emissions include benzene and formaldehyde, which, at low levels of exposure, can cause symptoms like allergic skin reactions and dry throats. However, at higher concentrations, or with prolonged exposure, this could lead to cancer. Other factors such as the degradation of building materials and the functions of the spaces itself can increase the VOC concentration causing derogatory health effects on the occupants( Singh et al. 2010; Salonen et al. 2009). A study of VOC concentrations in 176 office buildings, with formaldehyde readings taken for 23 of these building, revealed formaldehyde concentrations far exceeded the recommended indoor levels. This was a main factor for sensory irritation among occupants, compared to other non-reactive VOCs commonly found in the indoor environment( provided there were no other abnormal sources of VOCs)( Salonen et al. 2009).
Thermal standards as stated in the ISO Standard 7730:1994 defines acceptable thermal conditions as those which achieve at least 90 % of satisfied occupants, similar to the ASHRAE standards. In the study by Huizenga et al.( 2006), a prominent reason for occupant dissatisfaction was a lack of control over their indoor environment. Those that had control to thermostat settings had a satisfaction level of 76 % compared to 56 % for those without thermostat access. Occupants with operable windows had a 67 % satisfaction rating compared to 57 % for those without operable windows. The equal number of hot and cold complaints during summer shows the potential to improve the thermal quality of office spaces( C. Huizenga et al. 2006). Brightman et al.( 2008) compares results from the BASE survey with a study from the National Institute for Occupational Safety and Health( NIOSH). While the BASE study selected random offices across 201 US cities, the NIOSH survey specifically targeted‘ sick’ buildings. 30 % of the BASE survey respondents and 55 % of the NIOSH respondents were unhappy with their thermal environment. In a study that compared buildings with natural ventilation, mixed mode ventilation and air conditioning, the thermal factor was more critical in air conditioned buildings than in naturally ventilated ones( Kim & de Dear 2012). If the thermal environment in air conditioned buildings did not perform as per occupant expectations, there was a significant increase in the dissatisfaction levels, while at optimum performance; the thermal environment was almost unnoticed by the occupants. In comparison, since occupants of naturally ventilated buildings did not have high expectations of their thermal environment, if the thermal environment performed better than occupant expectations, it had a significant impact on the overall IEQ within the environment, and conversely less of a negative impact with a poor thermal environment( Kim & de Dear, 2012).
Similarly, Wagner et al.( 2007) shows that occupants in naturally ventilated buildings are satisfied with the indoor thermal comfort, even though the temperatures are higher than the comfort range in air conditioned buildings. This shows that efficient buildings that are passively cooled
850 ZEMCH 2015 | International Conference | Bari- Lecce, Italy