BS EN 15243:2007

BS EN 15243:2007 Ventilation for buildings. Calculation of room temperatures and of load and energy for buildings with room conditioning systems

The scope of this European Standard is: 

• To define the procedure how the calculation methods to determine the temperatures, sensible loads and energy demands for the rooms shall be used in the design process. 
• To describe the calculation methods to determine the latent room cooling and heating load, the building heating, cooling, humidification and dehumidification loads and the system heating, cooling, humidification and dehumidification loads.
• To define the general approach for the calculation of the overall energy performance of buildings with room conditioning systems.
• To describe one or more simplified calculation methods for the system energy requirements of specific system types, based on the building energy demand result from prEN ISO 13790, and to define their field of application. A general framework standard is given which imposes an hourly calculation for all cases which cannot be covered by simplified methods, and gives requirements on what has to be taken into account. Input and output data are defined. The target audience of this standard is twofold: 
• Designers of HVAC systems, which are given an overview of the design process with the relevant references to the different involved standards (Clauses 5 to 12). 
• Developers of regulations and tools, which find requirements for calculation procedures to be used for the energy requirements according to the EPBD (Clauses 13 and 14). 

The idea followed by this standard is, that for the detailed approach one single calculation method is used for the different room related purposes such as room temperature calculation, room cooling and heating load calculation, and room energy calculation. This means, for the building type envisaged (buildings with room conditioning systems) it is an alternative to simplified calculation methods such as heating load according to EN 12831 and heating energy according to prEN ISO 13790.

This standard does not describe any detailed methods for the sensible room based calculations. For this it refers to the relevant standards EN ISO 13791, EN ISO 13792, EN 15255 and EN 15265. This standard specifies simplified methods and describes the necessary functionality of methods for the calculation of standardized annual energy consumption by systems providing temperature control, mechanical ventilation and humidity control in existing and new buildings. For brevity, these are described as HVAC systems. These systems may provide any or all of these services, including heating, cooling, air filtration, humidification or dehumidification. For the air side calculations of air based systems it refers to EN 15241. Systems providing heating but no other services are covered by EN 15316.

These boundaries are, however, not kept strictly in the informative annexes, because some of the shown example calculations follow a holistic approach and this separation is therefore not always possible. The standard specifically relates to demand calculations needed for Energy Performance Rating in connection with the Energy Performance of Buildings Directive. These installations may include: 

• Emission, distribution, storage and generation for cooling. 
• Emission, distribution and heat exchanger for heating if these functions are performed using an air conditioning system; all heating functions performed by direct heating or using water as a heat transport medium are treated in other standards. 

The calculation of cooling and heating energy demand within buildings is dealt with by prEN ISO 13790 and is a required input. This standard only addresses these issues to the extent that HVAC systems have an influence on the loads.