ZEMCH 2015 - International Conference Proceedings | Page 852

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