الملخص الإنجليزي
The design practice of the government schools has undergone several changes,
which are also expected to influence their thermal and operational performance. Under
the current economic situation, the schools are obliged to reduce the operational cost,
especially after implementing the new cost-reflective tariff (CRT) structure in 2017,
which removes the governmental subsidy from high energy consumers. The concept
of net-zero energy schools has been proposed as a critical step to achieve self-sustained
buildings where passive, active, and renewable energy systems are considered.
Therefore, the aim of this research was to develop an optimal design for a net-zero
energy school in three representative climates of Oman; hot-humid climate represented
by Muscat, hot-dry climate represented by Nizwa, and moderate climate represented
by Salalah. A multiphase methodology was followed, including data collection of
typical schools from the Ministry of Education, collection of the capital cost of passive
and active systems from an approved list of contractors, an energy audit of a typical
school, and fieldwork measurements. A post-basic school with 20 classrooms located
in a hot-humid climate was selected as a school building prototype. The school was
modeled in the DesignBuilder software, a whole-building simulation package. The
model was validated using the fieldwork measurements, which was used to analyze
the school performance. The base case model shows that energy use intensity (EUI) is
142.5 kWh/m2
, which is considered slightly higher compared to other schools in hot
regions, typically between 84 to 93 kWh/m2
. The research revealed that the passive
and active design strategies are economically not feasible due to high capital cost, and
therefore savings in energy consumption and savings in energy cost were considered
as performance indicators. In general, the passive design strategies have shown
moderate potential in reducing energy consumption and energy cost in all climates. On
the other hand, active strategies such as LED lights, lighting control, and air
conditioning systems have shown more potential in reducing energy consumption and
energy cost. The optimal design for the three climates was then determined. The
research indicated that wall and roof insulations with a 50 mm thickness should be
used in hot climates but are not important in a moderate climate. High-performance
double clear low-E glazing with solar coatings is recommended in all climates.
Windows shadings are not recommended when daylighting is harvested since it may
hinder the savings in artificial lights. LED lights with dimming and variable refrigerant
flow (VRF) air conditioning are recommended active systems for all climates. The
optimal school design has reduced the energy consumption by 28.53%, 27.90%, and
25.14% in Muscat, Nizwa, and Salalah, respectively. The savings in energy costs were
29.9%, 29.5%, and 25.9% in Muscat, Nizwa, and Salalah, respectively. PV systems
were then integrated into the optimal school design to achieve net-zero energy status.
When integrating the PV systems and the optimal design strategies, the energy savings
for the school may reach up to 68.73%, 68.57%, and 65.76% in Muscat, Nizwa, and
Salalah, respectively, with the rest being injected into the national grid. Similar values
were also achieved for the reduction in the CO2 emissions and the energy cost,
achieving carbon-neutral and zero-cost energy schools.
