NKN
1114 visits
Posting Date | 12 February 2010
Type of tool | Simulation Tool
Countries where the tool has been developed | Czech Republic
Country where the tool is in use | Czech Republic
Geographic Coverage | National
Theme | Calculation, simulation, General
Target Group | Building professionals
Conditions of availability | Free
Input of the tool | User needs information about building geometry, areas, orientation, thermal characteristics of constructions (U-value), also information about the HVAC (heating, ventilation, and air conditioning) systems, the DHW (domestic hot water) systems, and any SES (solar energy systems), PVS (photovoltaic systems), wind generators or CHP (combined heat and power)generators used in the building.
The tool includes different standardized profiles of the use that may have different temperatures, operating periods, lighting standards, and climatic data.
Data are entered in the worksheets.
Output of the tool | Tool shows energy consumption of each system, the consumption of whole building and the final class of the energy performance of the whole building, or of the each HVAC system (heating system, cooling system, domestic hot water system, lighting of the building),
Strengths | Simple entering of the data, clear calculation procedure described in Excel cells, wide know MS Excel platform.
Weaknesses | The tool doesn’t calculate CO2 emissions, primary energy consumption. The tool is robust and slow due to programming language - MS Excel.
Tool Languages | Czech
The NKN calculation tool is based on the national calculation method and is created upon a simple spreadsheet in order to combine a compact and simple structure with easy access to testing the calculation methodology.
The methodology of this National calculation tool is based on the delivered energy needed under standard indoor and outdoor conditions. Energy consumption of the building is an amount of energy of the actual energy consumed or the expected amount of energy for the fulfilment of various demands related to the standard use of the building. In particular - heating, hot water preparation, cooling, treatment of air by ventilation and modification of parameters of the indoor environment by air condition system and lighting. The basic process of the calculation is commonly divided into two stages:
• calculation of energy demand of the building, or its parts – zones; it means the calculation of heat losses, and heat gains, required in each space in order to maintain specified internal conditions;
• calculation of energy consumption (building, or parts – zones, according to the energy demands) ; it means the calculation of the energy required by the energy systems (boilers, AHU units, DHW systems, lighting, etc.) needed to provide the necessary heating or cooling, or humidity control, etc..
The energy demand is calculated on the standard use of the building. The tool includes different standardized profiles of the use that may have different temperatures, operating periods, lighting standards, etc. The calculation method is based on the simplified dynamic calculation. The energy demand can be calculated from monthly, daily and hourly simplified values, but hourly calculations are better to represent the complexities of HVAC system (mainly because of cooling) performance.
Tool website URL(s) | http://tzb.fsv.cvut.cz/projects/nkn/?NKN_SID=70398481471ce966a3e9a7dcc4529b8f
Submitted by Hicham LAHMIDI (BUREAU VERITAS)
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