User Manual

19
Key:
[1] is the energy needed to fulfill the user's requirements for heating, lighting,
cooling etc., according to levels that are specified for the purposes of the calculation
[2] are the "natural" energy gains – passive solar, ventilation cooling, daylight,
etc. together with internal gains (occupants, lighting, electrical equipment, etc.)
[3] is the building's net energy use, obtained from [1] and [2] along with the characteristics of the building itself
[4] is the delivered energy, represented separately for each energy carrier,
inclusive of auxiliary energy, used by heating, cooling, ventilation, hot water and lighting systems, taking into
account renewable energy sources and co-generation. This may be expressed in energy units or in units of the
energyware (kg, m³, kWh, etc.)
[5] is renewable energy produced on the building premises
[6] is generated energy, produced on the premises and exported to the market; this can include part of [5]
[7] represents the primary energy usage or the CO
2
emissions associated with the building
[8] represents the primary energy or emissions associated with on-site generation that is used on-site and so is not
subtracted from [7]
[9] represents the primary energy or CO
2
savings associated with exported energy, which is subtracted from [7]
The overall calculation process involves following the energy flows from the left to the right of the
model above.
The model above is a schematic illustration and is not intended to cover all possibilities. For example,
a ground-source heat pump uses both electricity and renewable energy from the ground. And
electricity generated on-site by photovoltaics could be used within the building, it could be exported,
or a combination of these. Renewable energy sources like biomass are included in [7], but are
distinguished from non-renewable energy carriers by low CO
2
emissions. In the case of cooling, the
direction of energy flow is from the building to the system.
Energy demand and supply model
The BAC functions according to EN 15232 are based on the energy demand and supply model for a
building as shown below.
Rooms represent the source of energy demand. Suitable HVAC plants should ensure comfortable
conditions in the rooms with regard to temperature, humidity, air quality and light as needed.
Supply media is supplied to the consumer according to energy demand allowing you to keep losses
in distribution and generation to an absolute minimum.