54
S. F. Ali and D. Rakshit
Moreover, this has resulted in bringing the PPD value within the range specified by
standards, however, the value is nearer to the upper limit of the PPD range (ASHRAE
2010; ISO 2005). It is worth mentioning here that this forms the optimal solution
for the cases explored in this study, which has tried to improve the thermal comfort
conditions of the office room, still has not been successful in completely bringing it
within the ideal range for a comfort zone, hence, more passive strategies should be
explored and employed in order to maintain a thermally comfortable environment
for the occupants.
4.4 Conclusions
Building designers should focus on the comfort requirements of the occupants as well,
in addition to other goals. Employing passive design strategies can not only lead to
lowering the energy requirements of the building, but can also aid in improving the
thermal comfort in addition to other comfort parameters. The existing comfort level
for an office room has been determined, using the PMV and PPD models, and the
impact of different passive strategies on the comfort levels of the occupants have been
assessed. It was observed that application of different passive technologies resulted in
an improvement in the comfort conditions of the occupants. As compared to the base
case, the curve of PMV versus PPD approached closer to the ideal comfort range,
however, it was noticed that in each case, the curve shifted towards the positive side of
the PMV scale, indicating a zone of warmer environment. This resulted from the fact
that the cooler conditions inside the unconditioned building due to the ambient were
transforming into warmer conditions because of the heat being admitted inside from
the windows and the restriction to the heat flow from the inside to the outside due to
provision of different passive techniques. This, however, is still an improvement over
the base case as the maximum values of PMV as well as PPD was found to decrease,
since the study was done in the winter season, during which, a warmer environment
is preferred by the occupants.
An optimal solution with respect to the strategies explored in the study has been
proposed for the office room under analysis, which resulted in enhancement of the
comfort conditions. It has been observed that it is not necessary that the solution
obtained from employing individual strategies shall correspond to the optimal solution when a combination of the different passive techniques are used. When the
passive strategies were employed individually, the optimal solution for provision of
wall insulation was the fiber glass insulation of thickness 40 mm, which resulted in
percentage improvements of 63.11% and 12.61% on the negative and positive sides
of the PMV scale respectively, and 32.20% improvement in PPD value. Optimal roof
insulation, obtained with 40 mm thick fiber glass resulted in percentage improvements of 62.29% and 27.93% in minimum and maximum PMV values respectively,
and 49.17% in PPD. Similarly, low emissivity glazing was yielded as the optimal
solution out of the different window glazing studied, which resulted in percentage
improvements of 48.36%, 30.63% and 52.28% in the values of minimum PMV,
S. F. Ali and D. Rakshit
Moreover, this has resulted in bringing the PPD value within the range specified by
standards, however, the value is nearer to the upper limit of the PPD range (ASHRAE
2010; ISO 2005). It is worth mentioning here that this forms the optimal solution
for the cases explored in this study, which has tried to improve the thermal comfort
conditions of the office room, still has not been successful in completely bringing it
within the ideal range for a comfort zone, hence, more passive strategies should be
explored and employed in order to maintain a thermally comfortable environment
for the occupants.
4.4 Conclusions
Building designers should focus on the comfort requirements of the occupants as well,
in addition to other goals. Employing passive design strategies can not only lead to
lowering the energy requirements of the building, but can also aid in improving the
thermal comfort in addition to other comfort parameters. The existing comfort level
for an office room has been determined, using the PMV and PPD models, and the
impact of different passive strategies on the comfort levels of the occupants have been
assessed. It was observed that application of different passive technologies resulted in
an improvement in the comfort conditions of the occupants. As compared to the base
case, the curve of PMV versus PPD approached closer to the ideal comfort range,
however, it was noticed that in each case, the curve shifted towards the positive side of
the PMV scale, indicating a zone of warmer environment. This resulted from the fact
that the cooler conditions inside the unconditioned building due to the ambient were
transforming into warmer conditions because of the heat being admitted inside from
the windows and the restriction to the heat flow from the inside to the outside due to
provision of different passive techniques. This, however, is still an improvement over
the base case as the maximum values of PMV as well as PPD was found to decrease,
since the study was done in the winter season, during which, a warmer environment
is preferred by the occupants.
An optimal solution with respect to the strategies explored in the study has been
proposed for the office room under analysis, which resulted in enhancement of the
comfort conditions. It has been observed that it is not necessary that the solution
obtained from employing individual strategies shall correspond to the optimal solution when a combination of the different passive techniques are used. When the
passive strategies were employed individually, the optimal solution for provision of
wall insulation was the fiber glass insulation of thickness 40 mm, which resulted in
percentage improvements of 63.11% and 12.61% on the negative and positive sides
of the PMV scale respectively, and 32.20% improvement in PPD value. Optimal roof
insulation, obtained with 40 mm thick fiber glass resulted in percentage improvements of 62.29% and 27.93% in minimum and maximum PMV values respectively,
and 49.17% in PPD. Similarly, low emissivity glazing was yielded as the optimal
solution out of the different window glazing studied, which resulted in percentage
improvements of 48.36%, 30.63% and 52.28% in the values of minimum PMV,