In this stage, the research study examines the potential of the skycourt when it acts as an unheated and uncooled transitional buffer area that does not consume energy for heating nor cooling. In order to achieve energy savings for the building and better indoor thermal conditions in the skycourt, the study suggests three scenarios. In the first scenario, the skycourt use infiltration only (Figure 4-17). In the second scenario, the air extracted from the offices is driven through the office outlets and pushed into the skycourt inlets (Figure 4-18). In the third scenario, the fresh air is supplied to the skycourt space, then it is forced to extract into the adjacent offices (Figure 4-19).
Figure 4-17. Scenario one for unheated and uncooled skycourt: skycourt is a sealed space
Figure 4-18. Scenario two for unheated and uncooled skycourt: skycourt is ventilated by the exhaust air from the office spaces
Figure 4-19. Scenario three for unheated and uncooled skycourt: skycourt is ventilated by the supply air to the offices
Five ventilation strategies were suggested under the previous scenarios. The purpose is to identify the appropriate ventilation strategy for each prototype of skycourts in summer, winter and mid-seasons with respect to energy consumption and thermal comfort. The proposed ventilation strategies are:
(i) Sealed-skycourt ventilation strategy one (V1): this is based on infiltration only.
(ii) Combined-exhaust ventilation strategy two (V2): the skycourt is ventilated by
the exhaust air from the office spaces, all air enters through the office zone. Then, all air exhausts through the skycourt.
Exhaust air Supply air Exhaust air Supply air Exhaust air Supply air
Summer Winter Mid-season
Exhaust air Supply air Exhaust air Supply air Exhaust air Supply air
Summer Winter Mid-season Season Exhaust air Supply air Exhaust air Supply air Exhaust air Supply air
(iii) Combined-exhaust ventilation strategy three (V3): the skycourt is ventilated by half of the exhaust air from the office spaces, air enters through the office zone. Then, half of the air exhausts through the skycourt, and the other half through the office zone.
(iv) Combined-supply ventilation strategy four (V4): the skycourt is ventilated by
the supply fresh air to the office spaces. All air enters through the skycourt zone, and then, the air exhausts through the office zone.
(v) Combined-supply ventilation strategy five (V5): the skycourt is ventilated by
half of the supply fresh air to the office spaces. Half of the fresh air enters through the skycourt zone, and the other half through the office zone. Then, all air exhausts through the office zone.
Figure 4-20 illustrates these strategies, air movement, and simulation settings for the skycourt.
Skycourt is a sealed space Strategy one (V1)
Skycourt is unheated and uncooled buffer zone, adopts infiltration only
Skycourt is ventilated by the exhaust air from the office zones Strategy two (V2)
Strategy three (V3)
All supply air enters through the offices. All air exhausts through the skycourt
All supply air enters through the offices. Half of exhausts air enters the skycourt, and the other half exhausts through the offices Inlet air volume rate 5.58
m3/s*
Inlet air volume rate 2.79
m3/s*
Skycourt is ventilated by the supply air required for the office zones Strategy four (V4) Strategy five (V5)
All supply air enters through the skycourt. All air exhausts through the offices
Supply air is distributed between the skycourt and the offices equally. All air exhausts through the offices Inlet air volume rate 5.58
m3/s*
Inlet air volume rate 2.79
m3/s*
* These settings are defined for the skycourt
Figure 4-20. Proposed ventilation strategies for the skycourt for stage two
2a. air enters through offices’ zone and all warm air exhausts through skycourt
2b. air enters through offices’ zone and half of warm air exhausts through skycourt, and the other half through the offices’ zone
Exhaust air Supply air Exhaust air Supply air Exhaust air Supply air Exhaust air Supply air Exhaust air Supply air
The proposed location of air inlet and air outlet openings in this stage are the same in all cases. Air inlet openings are inserted at the floor level of the skycourt, and air outlet openings are inserted at the ceiling level of the skycourt. Displacement ventilation is assumed to determine air distribution in the skycourt when air enters the skycourt. It is anticipated that this system can be an efficient alternative in the skycourt.
Supply air temperature is based on the principle of the case under study. For example, in the case of the combined-exhaust strategies, supply air temperature depends on the air temperature extracted from the offices, while, for combined-supply strategies, it is assumed to be 18°C or more based on the external air temperature.
The study involves modifying each of the ventilation strategies in the input data while keeping the other parameters fixed. Each ventilation strategy was tested under three seasons: summer, winter and transitional seasons. The total number of the simulation cases in this stage is 60. Fixed and independent variables are summarised in Table 4-12. These are:
- Three prototypes (spatial configurations) of skycourts: Prototype (A): hollowed-out space
Prototype (B): corner space Prototype (C): sided space
- Five ventilation strategies, which have been defined previously
- Three times for CFD simulation:
The hottest hour in summer months (June, July and August)
The coldest hour in winter months (December, January and February)
A typical hour in mid-season months (March, April, May, September, October and November)
Table 4-13. Fixed and independent settings for stage two
Fixed Parameters Details
Climate conditions London climate Geometrical properties of the models As defined in Table 4-2
Energy simulation conditions As defined in Table 4-10 and Figure 4-15 CFD simulation conditions As defined in Table 4-9
Independent variables Details
Tested prototypes/models Three models:
Prototype (A): hollowed-out space Prototype (B): corner space Prototype (C): sided space Ventilation strategies Five strategies:
Strategy one (V1) Strategy two (V2) Strategy three (V3) Strategy four (V4) Strategy five (V5)
Weather seasons Three times in weather seasons, these are: Summer (Jun., Jul., Aug.)
- Hottest hour: 28 Jun. at 14.00 Winter (Dec., Jan., Feb.)
- Coldest hour: 7 Dec. at 9.00 am
Mid-seasons (Mar., Apr., May, Sep., Oct., Nov.) - Typical: 19 Apr. at 9.00 am
The air temperature and the air speed for the skycourt (calculated using the thermal simulation software, HTB2) were compared against the measured data from the CFD simulation process using WinAir.
This stage aims to identify the most suitable ventilation strategy to be utilised inside the skycourt. This strategy will obtain the most energy savings with respect to heating and cooling loads of the building, and in addition provide thermal comfort for the occupants of the skycourt. The most suitable alternative will also positively affect the adjacent offices. The result will greatly simplify further investigation of the key parameters to determine the most critical ventilation conditions in the next stage.