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Aquarea air-to-water heat pumps - Planning and installation manual - 02/2022
Planning
5
Example of Germany: Typical values for the specic heating load of residential buildings for 
rough determination of the design heat load
Existing building up to 1977   130  to  200 W / m²  
Building after 1977   70  to 130 W / m²   
Building after 1982   60  to 100 W / m²   
Building after 1995   40  to 60 W / m²   
Building after 2002   30  to 50 W / m²   
Low energy house   25  to 40 W / m²   
Ultra-low energy house   15 to  30 W / m²  
Passive 10 W / m²   
Example
In the case of a residential house in Frankfurt/Main from the year 1992 with a heated living space 
of 120 m², the design heat load thus calculated is 9.6 kW (80 W/m²).
The design outside temperature for the residential house can be read from the table of the design 
outside temperatures for the observed location with θe = -12 °C. The heat pump should therefore 
provide the determined heating capacity of 9.6 kW at an outside temperature of -12 °C.
 
!
 IMPORTANT
The approximate calculation method shown only yields rough reference values for the heat load. 
For correct designing, a heating expert must precisely calculate the required heating capacity 
in order to provide the correct design. Panasonic cannot be held responsible for any wrong 
calculations under any circumstances.
5.1.2  Determination of the domestic hot water demand
The domestic hot water demand can only be estimated based on the following table for various 
comfort expectations.
Example of Germany: Typical domestic hot water demand per person for one or two family 
houses at 45 °C tapping temperature.
Comfort expectation Daily requirement per person in 
litres (45 °C)
kW per person and day
Low  15 to 30  0.6 to 1.2
Normal  30 to 60  1.2 to 2.4
High  60 to 120  2.4 to 4.8
Washing machine or dishwasher 
with hot water mode
≈ 20
(See manufacturer's documents)
0.8
Depending on the number of persons and the comfort expectations, the domestic hot water 
demand can be very dierent. It is advisable to select the size of the domestic hot water tank 
according to the domestic hot water demand. It is important to make sure that the hot water output 
capacity required (e.g. 120 litres for a bath) is covered by the tank volume. At the same time, do not 
choose an unnecessarily large tank volume, to ensure low dwell time in the tank. For one and two 
family houses, the tank sizes given in the following table are recommended.
Example of Germany: Recommended tank sizes for one and two family houses
Persons  Tank volume
2 to 3  200 l
3 to 6  300 l
> 6  > 300 l