AERMEC RePuro 650 - Page 15

15
IREPPY - 1404 - 4238051_01
4.4. EXAMPLE OF ENERGY SAVING
CALCULATION
The following shows an analysis made on
the energy advantage for the heat recov-
ery solution used in a residential building
located in 2468 DD climatic zone (EN ISO
15927-6:2007).
The analysis takes into consideration a por-
tion of a twin apartment, with useful sur-
face area of 150m
2
. The dwelling consists of
two stacked floors.
The chart shows the winter primary ener-
gy use (EPi) expressed in kWh/(m
2
x year)
of the same building.
In the three cases the EPi value of the en-
closure is equal at 37,578 kWh/(m
2
per
year), whilst the dierence in the columns
is due to the air renewal variaon in re-
newal rate and how it is achieved.
0
10
20
30
40
50
60
37,578
With renewal rate
0.3Vol/h
without recovery
EPi kWh/(m
2
per year)
With renewal rate 0.5Vol/h
recovery eciency 50%
With renewal rate 0.5Vol/h
recovery eciency 90%
In the absence of controlled mechanical
venlaon the air ow renewal rate of
spaces is xed at 0.3Vol/h: in such a case
the EPi index of the building is esmated as
55,978kWh/(m
2
per year).
Such air renewal is not sucient to have
a good space air quality which must be at
least 0.5vol/h according to EN 15251. Such
a renewal rate can be obtained with a me-
chanical venlaon system with eciency
of 50%: in which case the EPi becomes
52,928 kWh/(m
2
per year).
If instead a high eciency mechanical ven-
laon system like RePuro is used, this re-
quirement becomes 40,522kWh/(m
2
per
year).
In the rst case (aeraon) of the building is
in class B for energy performance for win-
ter condioning and the air quality is low.
In the last case with high eciency heat re-
covery not only is the minimum air renewal
in accordance with standard EN 15251, but
the building increases its energy perfor-
mance for winter condioning.
For the soluon with mechanical venla-
on (CMV) with 50% eciency the EPi
increases considerably with increasing air
renewal rates, but with the RePuro solu-
on the value also increases, but consider-
ably less.
0
20
40
60
80
1
00
0,3 Vol/h
1 Vol/h 0,7 Vol/h 0,5 Vol/h
EPi kWh/(m
2
per year)
Aeraon or natural
venlaon
With MV eciency 50%
With MV
eciency 90%
* S/V = Relaonship between the outer surface of the volume heated to unheated spaces (surface area loss) and the gross volume of the heated parts of
the building heated
Useful surface area m
2
150
Surface loss area m
2
315
Gross volume heated m
3
450
S/V * 1/m 0,7
Climatic zone (EN ISO 15927-6:2007) Degree-Days (DD) 2468
EPi limit 2010 kWh/(m
2
per year) 82,245
Window transmiance W/(m
2
x K) 1,513
Wall transmiance W/(m
2
x K) 0,255
Floor transmiance W/(m
2
x K) 0,185
Ceiling transmiance W/(m
2
x K) 0,310