Comfort Control Techniques for the Users of a Room - Comfort Control in Buildings - page 197

Table 5.4 Energy consumption derived from the different test
Test Classical Hierarchical Energy

MPC (kWh) controller (kWh) saving ( % )

(A) 22 . 8297 10 . 6566 53 . 3213

(B) 23 . 3345 10 . 9238 53 . 1856

(C) 35 . 3920 20 . 4158 42 . 3175

(D) 44 . 7552 19 . 7960 55 . 7681

Fig. 5.37 Hierarchical thermal comfort and indoor air quality PNMPC system architecture

Generally, thermal comfort conditions have been controlled by performing a
regulation of indoor air temperature, and indoor air quality by means of CO 2 con-
centration since it is the main waste from occupants inside buildings (Atthajariyakul
and Leephakpreeda 2004 ). On the one hand, thermal comfort control is performed
by means of HVAC systems. On the other hand, the most used technique to main-
tain indoor air quality is ventilation: forced ventilation through the use of HVAC
systems, or natural ventilation by means of the window. Nevertheless, when the ven-
tilation rate inside an environment is increased or decreased, indoor air temperature
is directly affected, and thus, thermal comfort too. Therefore, it is a multivariable
control problem, where it is necessary to reach a tradeoff between thermal comfort
and indoor air quality.
A hierarchical control architecture which is used to regulate both thermal comfort
and indoor air quality inside a typical office room of the CDdI-CIESOL-ARFRISOL
building is proposed in Fig. 5.37 . It is based on the PNMPC algorithm presented
in Sect. 5.2.3 , and makes use of the first principles model showed in Sect. 4.2.2 of
Chap. 4 . The main control objective is to maintain users' thermal comfort and indoor
air quality conditions inside a comfort zone defined by the PMV and IAQ indices, see