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Chapter 1: Method for Calculating the Design Primary Energy Consumption

This chapter describes the method for calculating the design primary energy consumption.
The design primary energy consumption \(E_{T}\) [GJ/year] is calculated using the following equation, and the result is rounded up to the second decimal place.

\[ E_{T} = (E_{AC} + E_{V} + E_{L} + E_{HW} + E_{EV} - E_{PV} - E_{CGS} + E_{M}) \times 10^{-3} \]
  • \(E_{AC}\) is the design primary energy consumption of the air-conditioning system [MJ/year], described in Chapter 2.
  • \(E_{V}\) is the design primary energy consumption of the mechanical ventilation system [MJ/year], described in Chapter 3.
  • \(E_{L}\) is the design primary energy consumption of the lighting system [MJ/year], described in Chapter 4.
  • \(E_{HW}\) is the design primary energy consumption of the hot water supply system [MJ/year], described in Chapter 5.
  • \(E_{EV}\) is the design primary energy consumption of elevators [MJ/year], described in Chapter 6.
  • \(E_{PV}\) is the reduction in primary energy consumption due to photovoltaic (PV) systems [MJ/year], described in Chapter 7.
  • \(E_{CGS}\) is the reduction in primary energy consumption due to cogeneration systems [MJ/year], described in Chapter 8.
  • \(E_{M}\) is the primary energy consumption from other sources [MJ/year], described in Chapter 9.

Constants commonly used across the calculations for all building systems

Table 1. Common Constants
Constant Description Value Unit
\( f_{\mathrm{prim},e} \)Conversion factor from 1 kWh of electricity to heat energy 9760 kJ/kWh
\( C_{a} \) Specific heat capacity of dry air at constant pressure 1.006 kJ⁄(kg·K)
\( C_{wv} \) Specific heat capacity of water vapor at constant pressure 1.805 kJ⁄(kg·K)
\( C_{w} \) Specific heat capacity of water at constant pressure 4.186 kJ⁄(kg·K)
\( L_{w} \) Latent heat of vaporization of water 2502 kJ⁄(kg·K)
\( \rho_{w} \) Density of water (at atmospheric pressure, 7°C) 1000 kg⁄$m^{3}$
\( \alpha_{o} \) Total heat transfer coefficient on the exterior side 1/0.04 W/($m^{2}$·K)
\( \alpha_{i} \) Total heat transfer coefficient on the interior side 1/0.11 W/($m^{2}$·K)
\( f_{fan,heat} \) Heat generation ratio of fans 0.84 -
\( f_{pump,heat} \) Heat generation ratio of pumps 0.84 -
\( f_{ref,ts,loss} \) Heat loss factor of thermal storage tanks 0.03 -

Databases Used for Calculation

References

  • Building Research Report No. 201: Study on Primary Energy Conversion Factors for New District Heating and Cooling Plants, Sep. 2020
  • NILIM Report No. 1107: Survey on Building Envelope and Equipment Design Specifications and Actual Energy Performance of Non-Residential Buildings – Analysis of Input/Output Data from the Energy Efficiency Compliance Program –, Mar. 2020
  • Building Research Report No. 191: Study on the Advancement of Performance Evaluation Methods for Commercial Cogeneration Systems, Apr. 2019
  • Building Research Report No. 190: Study on Energy Consumption Evaluation Methods Considering Latent Heat Load Processing Mechanisms of Various HVAC Systems, Apr. 2019
  • Building Research Report No. 188: Study on the Estimation Method of Annual Power Generation from Photovoltaic Systems, Jan. 2018
  • Building Research Report No. 187: Survey on Existing Test Methods for the Energy Efficiency of Building Equipment and Systems, Sep. 2017
  • NILIM Report No. 974 / Building Research Report No. 183: Technical Documentation on the 2016 Energy Efficiency Standards – Guide to the Model Building Method Input Support Tool –, Jun. 2017
  • NILIM Report No. 973 / Building Research Report No. 182: Technical Documentation on the 2016 Energy Efficiency Standards – Guide to the Energy Consumption Calculation Program (Non-residential version) –, Jun. 2017
  • Building Research Report No. 177: Empirical Evaluation of Energy-Saving Effects from Control of Commercial HVAC and Hot Water Systems, Nov. 2016
  • Building Research Report No. 176: Basic Survey on Energy Consumption Evaluation Methods for Commercial Buildings, Nov. 2016
  • NILIM Report No. 765 / Building Research Report No. 152: Technical Documentation on the 2013 Energy Efficiency Standards – Guide to the Envelope Performance and Primary Energy Consumption Evaluation Program using the Model Building Method –, Nov. 2013
  • NILIM Report No. 764 / Building Research Report No. 151: Technical Documentation on the 2013 Energy Efficiency Standards – Guide to the Primary Energy Consumption Calculation Program using the Key Room Input Method –, Nov. 2013
  • NILIM Report No. 763 / Building Research Report No. 150: Technical Documentation on the 2013 Energy Efficiency Standards – Guide to the Building Envelope Performance Evaluation Program for Non-Residential Buildings –, Nov. 2013
  • NILIM Report No. 762 / Building Research Report No. 149: Technical Documentation on the 2013 Energy Efficiency Standards – Guide to the Primary Energy Consumption Calculation Program (Non-Residential Buildings Edition) –, Nov. 2013
  • NILIM Report No. 702 / Building Research Report No. 140: Technical Documentation on the Low-Carbon Building Certification Standards (Announced Dec. 2012) – Guide to the Primary Energy Consumption Calculation Program (Buildings Edition) –, Dec. 2012