3 minute read
6.6 Application of solar heating/ cooling system
by jacques_23
environmental conditions for human occupancy specify the combinations of indoor environmental and personal factors that produce acceptable thermal conditions for most occupants within a space (ASHRAE, 2013). Furthermore, assuming slow air movement (less than 12m per minute) and 50% indoor relative humidity, the operative temperatures recommended by ASHRAE range from 20°C to 23°C in the winter, and from 23°C to 26.6°C in the summer. The temperature range is related to the change in clothing depending on the season.
6.5.6 CONCLUSION FROM COM PARISON
Advertisement
After comparing the results with the ASHRAE standards, the enclosed heating system proved to be the most efficient as the system was able to discharge heat within the thermal comfort range for 5 hours on average. The ventilated system was only able to discharge heat within the thermal comfort range for 2 hours.
After comparing the results from the cooling system, the ventilated system proved to be the most efficient as the system proved to provide cooled air between the range of 23°C and 26.6°C for 12 hours on average compared to the 5 hours of cooled air provided from the enclosed system.
6.6 APPLICATION OF SOLAR HE ATING/ COOLING SYSTEM
The solar heating system is proposed to be installed on housing units either as a retrofit or as part of a newly built housing unit. For this section, a 24.3m³ (3000mm x 3000mm x 2400m) housing unit will be used as an example.
Calculation of rock bed required: 24.3m³ x 0,25m³ (Rock) = 6.075m³
Calculation of solar air heater:
0,5m² x 24.3m³ = 12,15m² The solar air heater can be constructed in separate panels to make up the required size of the panel or constructed in one large panel.
6.6.1 New built solar heating system application
To install the solar heating system on a newly built housing unit, it is proposed that the rock bed be placed below the surface bed of the housing unit with the solar air heater fixed to the northern wall in a vertical position. The solar air heater should swivel to allow for seasonal change as and when the system is required.
The rock bed below the floor slab will be heated by the hot air supplied by the solar air heater during the winter season; the heat from the rocks will also radiate through the floor slab into the space/room. Refer to Figure 80 for an illustration of the proposed application of the solar heating system.
It is proposed that the solar air heater be placed on the side of the housing at a vertical position with hinges to lift the bottom of the solar air heater during the winter to generate heat and retract during the summer for the system to be used for cooling.
Figure 80: Solar heating system application on newly built housing unit ( Author, 2021)
6.6.2 Retrofit solar heating system application
To retrofit the solar heating system on an existing housing unit, it is proposed that the rock bed be placed in a trench next to the housing unit. As illustrated in Figure 81, the trench is proposed to be covered with a timber sheet with a concrete slab cast in-situ on top of the rock bed. A concrete slab is cast in situ at the bottom of the rock bed with a wall on the side to limit heat loss.
As illustrated in Figure 81, it is also proposed that the solar air heater is placed on the northern with hinges to tilt for seasonal change. The disadvantage of this system is that the heat will not transfer directly into the space through the floor. Refer to Figure 81 for the illustration of the retrofit application.
