ZEMCH 2015 - International Conference Proceedings | Page 854

(SBS) symptoms, increase occupant satisfaction of IAQ, and improve the work performance and
productivity (Fisk, 2012; Seppanen et al. 2006; Fisk et al. 2009). A reduction in ventilation rate from
10 to 5 l/s per person results in a significant increase of SBS symptoms by approximately 23% (12%
to 32%) (Fisk et al. 2009). Increasing the rate from 10 to 25 l/s per person showed a reduction in SBS
symptoms of approximately 29% (15% to 42%). On average, increasing the rate beyond 25 l/s per
person does not lead to substantial reductions in the SBS symptoms. Thus, although increasing
the ventilation rate improves occupant satisfaction, there should be a balance with the consequent economic aspect.
Fisk (2012) analyses the economic and health outcomes of varying ventilation rates within an office based on the ASHRAE standard of 8.5 l/s for the default occupant density of 5 persons per
100 m2 of floor area. After statistical analysis of various scenarios, the most feasible option was
to add economisers to half the sample offices that did not have this facility. An economiser is
a mechanical control system that allows the increase of ventilation rates above the minimum
requirement when the additional ventilation will allow a reduction in air conditioning required
thereby achieving energy efficiency. According to this study, although there is an installation cost
of $0.42 billion, this option is expected to improve the work performance by 1.6% in 20.7 million
employees, avert SBS symptoms in 1.2 million employees thereby preventing 28 million days of
short term absence, which results in economic benefits of $32.9 billion. The use of economisers
in this scenario also results in savings of $0.32 billion in a year. Although these numbers may not
seem substantial at an individual level, it cannot be overlooked when considering the overall office employee population. In the various scenarios tested, the economic benefits ranged from $13
billion to $38 billion per year. In comparison to the savings that can be generated, the potential
costs of implementing these strategies are quite minimal (Fisk 2012).
Feige et al. (2013) noted that occupants of green buildings have greater control over their immediate surroundings compared to those in conventional buildings. Most of the windows in the
former are operable, thereby providing greater control of ventilation options to the occupants.
Fully automated buildings without occupant control of operating systems, showed higher levels
of occupant dissatisfaction. The flexibility to change the workspace to respond to the nature of
the tasks, allow a greater perception of individual, and sometimes group, control over the work
environment. The study also showed that buildings which incorporated occupants’ comfort and
energy efficiency within the early stages of the building design and development were more successful in creating efficient and flexible indoor environments (Feige et al. 2013).
According to Roulet et al. (2006) employee productivity is greater in green buildings. 95% of occupants of green buildings did not have any absenteeism related to the indoor environment, compared to 87% in conventional buildings. Occupants in LEED certified buildings are significantly
more satisfied than those in traditional office buildings. The optimum guidelines for good indoor
spaces are often integrated with the energy rating standards such as BREEAM, LEED and so forth
(Kim & de Dear 2012). Using these rating systems as a guideline can enable designers to create
viable workspaces. A study conducted by Leaman and Bordass (2007) showed that the occupants
of green buildings tend to more tolerant of the indoor environment, although this could also be
due to the fact that such buildings often accommodate optimum levels of indoor environmental
quality factors. However, problems that arise in green buildings are often repeated in future construction as the implementation of changes and improvements are very slow.
The typology of the offices also has an impact on the indoor environment, with occupants in
open offices reporting more SBS symptoms (Pejtersen et al. 2006). Open plan offices are those

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ZEMCH 2015 | International Conference | Bari - Lecce, Italy