{"id":143952,"date":"2026-05-28T17:07:27","date_gmt":"2026-05-28T15:07:27","guid":{"rendered":"https:\/\/www.velasolaris.com\/?post_type=handbuch&p=143952"},"modified":"2026-05-28T17:10:28","modified_gmt":"2026-05-28T15:10:28","slug":"heating-load-and-heating-energy-demand","status":"publish","type":"handbuch","link":"https:\/\/www.velasolaris.com\/en\/handbuch\/polysun-designer\/energy-demand-circuit\/thermal-consumers\/building\/heating-load-and-heating-energy-demand\/","title":{"rendered":"Degree Hour Model: Heating Load and Heating Energy Demand"},"content":{"rendered":"\n

Entry of Heating Load and Heating Energy Demand for Energy Simulation<\/h1>\n\n\n\n

This article is aimed at Polysun users and explains how the heating load and heating energy demand can be used as input parameters for system simulation.<\/p>\n\n\n\n

In order to accurately size an energy system \u2013 such as a heat pump or hybrid energy system \u2013 the building\u2019s thermal heat demand must be determined in the simulation. If calculations for the heating load and the heating energy demand are available, these two values can be used to define the building\u2019s thermal behavior.<\/p>\n\n\n\n

The heating load indicates the maximum power [kW] that must be supplied to the system (e.g. a building). The heating energy demand, on the other hand, indicates how much energy [kWh] must be supplied over the course of a year. These two figures are used to determine how much heat the energy system must provide in order to maintain the desired room temperature.<\/p>\n\n\n\n

Entering Heating Load and Heating Energy Demand as Parameters<\/h2>\n\n\n\n

In the building component, once the degree-hour model has been selected, the two input fields \u2018Heating energy demand\u2019 and \u2018Heating load\u2019 will appear and can be filled in accordingly.<\/p>\n\n\n\n

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In addition to heating energy demand and the heating load, the heating setpoint temperature is important for the degree-hour model. It influences the balance temperature \u2014 the outdoor temperature at which the building is in thermal equilibrium and requires neither heating nor cooling. A detailed description of how degree-hour model works can be found here<\/a>.<\/p>\n\n\n\n

Validating the Entered Heating Load<\/h2>\n\n\n\n

The peak in heating load occurs at the given design outdoor temperature. Polysun determines the design outdoor temperature based on weather data<\/a>, calculating it as the lowest temperature that persists for at least two hours, reduced by 2 \u00b0C. The heating energy demand is distributed over the year based on the hourly outdoor temperatures from the weather data. This behavior can be visualized and validated in the graphical evaluation<\/a>.<\/p>\n\n\n\n

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Manual Adjustment of the Design Outdoor Temperature<\/h2>\n\n\n\n

Heating load calculation software indicates the design outdoor temperature at which the peak heat load has been calculated. If this temperature differs from the outdoor temperature calculated by Polysun, the user can override this input manually.<\/p>\n\n\n\n

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This manually entered temperature indicates the point at which the peak heating load occurs:<\/p>\n\n\n\n