Design Criteria

1-Calculations Software

The software's that will be used in our calculations are:

HAP 4.41 (Hourly analysis program) for cooling load and equipment capacity calculations.

2-Codes and Standard

ASHRAEAmerican Society of Heating Refrigerating and Air

Conditioning Engineering (edition 2007)

3- Design Conditions

The selection of the appropriate HVAC design conditions (inside design conditions, outside design condition, internal load sources intensity and building thermal characteristics) has a direct impact on: The estimation of the ventilation and cooling capacity of the system.

The sizing of the HVAC system components.

The verification of the requirements of the thermal comfort and indoor air quality inside the building.

Outside Design Conditions

The outside design conditions given by ASHRAE Handbook (Fundamental 2009) recommendation for KSA is given in Table 1. The outside conditions given in the ASHRAE Handbook do not express the current actual weather conditions in KSA. Therefore the outside design conditions used in our cooling load calculation will be based on the Temperature listed in the Equipment Schedule. These conditions express the actual weather conditions in KSA in these years. These outside design conditions are given in Table 1.

Table 1 Outside Design Conditions

Outside ConditionsASHRAE HandbookPresent Calculation

Dry bulb Temperature C(F)44(111)45(111)

Wet bulb Temperature C(F)21.7(71)29.4(85)

Daily Range (K) (F)13.3(23.9)13.3(23.9)

Elevation m(ft)17(55)

Lat. (deg)26.3 N

5- Inside Design Conditions

The inside design conditions used in our cooling load calculation is taken based on the recommendation of ASHRAE Handbook (Fundamental 2009) for human thermal comfort. Table 2 gives these recommendations.

Table 2: Inside Design Conditions (ASHRAE Recommendations)

ApplicationsDesign TemperatureDesign RHPRESENT DESIGN

All zonesASHRAE RECOM.PRESENT DESIGNASHRAE RECOM.PRESENT DESIGNACCORDING TO ASHRAE STANDARD 62-2007

23-26 (C)221 (C)40-60 %505 %

6- Occupancy density

As per furniture layout

7- lighting

As per approved lighting shop drawings

8- Fresh air requirements

As per ASHARE and to cover direct exhaust from building.

9- Equipment loads

As per ASHRAE2007

This equipments load for covering equipments load and any misalliances load.

10- U Value for Walls, Glass and Roof

The U-factors for the walls, glass and roof are taken in our calculations based on the properties of the materials that are given in the Architecture Drawings and is commonly used in building construction in KSA as follows:

External wall (0.232 Btu/hr/ft2/f)

partition (0.41 Btu/hr/ft2/f)

Roof (0.068 Btu/hr/ft2/f)

Floor (0.1 Btu/hr/ft2/f)

Glasses (0.511 Btu/hr/ft2/f)