analysis of the influences of solar radiation and façade glazing ...

3.5 Optimization of a solar domestic hot water system 91
The total gross area of the solar collectors, which are connected in a parallel liquid flow, is
equal to 40.32 m 2 . For numerical calculations of energy conversion, the solar panel thermal
performance was adapted from SRCC (2007).
3.5.2 Solar heating systems control
The efficiency of HVAC systems strongly depends on the algorithm which controls the
operation. “The differential thermostat” is chosen to control a developed solar heating
system. In this type of regulation technique, the temperature in the water heater is
compared to the temperature inside the solar collector loop. The pump is turned on when
there is a useful heat gain.
In the current analysis, the Temperature Difference On Limit was set to 10°C and the
Temperature Difference Off Limit was set to 2°C. If the temperature difference between the
collector outlet and the storage tank source outlet was above the Temperature Difference
On Limit, the system was turned on. The system was turned off when the temperature
difference was below the Temperature Difference Off Limit.
3.5.3 Assumed parameters of domestic hot water systems
In accordance to the building owner’s suggestion, each apartment will be occupied by two
persons. The average DHW consumption was estimated at 30 litres per person per day. It
resulted in an annual consumption of 416.1 m 3 . The temperature of the DHW in the storage
tank was set to 60°C and a mixed temperature in the water tap was set to 45°C.
The simulations included domestic hot water use such as showers, dishwashers, washing
machines, dryers and all types of water outlets together. The following schedule of hot
water equipment use was established.
Table 3.12: Schedules for DHW equipment
Sinks schedule Showers schedule Clotheswasher schedule Dishwasher schedule
Through: 12/31,
For: AllDays,
Until: 7:00,
0.0,
Until: 8:00,
0.3,
Until: 9:00,
0.7,
Until: 11:00,
0.0,
Until: 12:00,
0.1,
Until: 13:00,
0.3,
Until: 17:00,
0.0,
Through: 12/31,
For: AllDays,
Until: 6:00,
0.0,
Until: 6:30,
0.2,
Until: 7:00,
0.9,
Until: 7:30,
0.0,
Until: 13:00,
0.0,
Until: 19:30,
0.7,
Until: 24:00,
0.0;
Through: 12/31,
For: Weekends
SummerDesignDay
WinterDesignDay,
Until: 6:00,
0.0,
Until: 7:00,
1.0,
Until: 12:00,
0.0,
Until: 24:00,
0.0;
For: AllOtherDays,
Until: 24:00,
0.0;
Through: 12/31,
For: AllDays,
Until: 20:00,
0.0,
Until: 20:30,
1.0,
Until: 22:00,
0.0,
Until: 24:00,
0.0;