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HOURLY CALCULATION METHOD (52016) (Energy balance bld Element (ISO 52016…
HOURLY CALCULATION
METHOD (52016)
Principles
Application:
energy need
internal temp
design heating/cooling need
Interval
Full year
Peak indoor temperature/
design load: > Short period
Assumptions
External surfaces:
External radiant env = external air temp
Convective heat transfer = f( wind direction/speed ), time-independent
Long-wave heat transfer = time-independent
Envelope:
Thermal zone = closed, by elements
Dimensions approach (internal/overall..) = const during assessement
Thermo-physical prop = time-independent
Spatial solar radiation distribution = time-independent
Windows = solar angle-independent
Solar energy = only transmitted
:pen:
Mean radiant temp
=
Average of internal temp of each elements
weighted on its area
Needs/loads
Basic
:
technical system always on
system power unrestrictred
only convective heat
standard indoor conditions
System specific
:
characteristics/control
of technical bld system
Influences:
may limited power
convective fraction
recoverable heat losses
different temp set-points
may limited H/C season
:pen: Energy need
Q
Sensible H/C:
monthly, per Zone Thermally Conditioned
annual, per zth
Latent for (de-)humidification:
monthly, per zth
annual, per zth
Internal temp calculation
system-independent
For standard temp
-> Zero H/C power
-> Set max power=0
Sensible H load
:pen:
of a ztc
for a sub-system
Climatic data (ISO 15927)
Avg ext air temp = ext design temp
Min hourly temp: must occur on avg 20 times in 20 years
Initialization period=14 days
Internal gains = reduced by a factor
f
Sensible C load
:pen:
of a ztc
for a sub-system
Set-points & Internal gains:
simultaneity factors for usage data
--> none factors/data used directly
Climatic data:
same as H
Supply air condition
for (de-)Humidification
:pen:
moisture load
latent H load
Calculation procedure
Situations
None H/C / free floating condition
-> int temp calculated
Need C & sufficient
--> int temp = set-point
Need H & sufficient
--> int temp = set point
Need C - insufficient
--> int temp > set-point
Need H - insufficient
--> int temp < set-point
For each hour/zone -->
int op temp
&
actual H/C load
1) C/H needed?
2) Set-point apply? --> H/C load
3) H/C power sufficient?
4) If no: --> int temp
5) --> Actual H/C load
:pen: Thermal bridges
Overall heat transfer coefficient
H = Σ ( l Ψ ),
l: lengh ; Ψ: linear thermal trasmittance
Energy balance bld Element
Opaque/Internal partition -->
2 on surfaces + 3 inside
ISO 13789:
--> Area, Thermal resistance
Touching the ground -->
ext heat transfer coeff =
thermal conductance of ground layer
ISO 13789 + 13370:
Area ; Virtual ground temperature
Floor effective thermal resistance (considering Ground)
R & k of 0,5 ground layer
Windows/Doors --> 2
h = 1 / R
ISO 52016-1
Conductance
btw nodes:
h4 = h1 = 6/R
h2 =h3 = 3/R
Classes:
I (mass concentrated inwards)
E (mass concentrated outwards)
IE (mass divided over int & ext)
D (mass equally distributed)
M (mass concentrated inside)
I --> k5=km
E --> k1=km
IE --> k1=k5=km/2
D --> k1=k5=k/8 ; k2,3,4=km/4
M --> k3=km
Areal heat capacity
k
:
very light -- very heavy
no mass component -- > 12 cm bricks/concrete
Italian National Annex
1) :pen:
Fourier number
, each layer
2)
Fo(ref)
=0,5
3) :pen: Number of capacity nodes (Ncn)
4) Number of nodes = S(Ncn) + 2
5) Data:
mass density
and
thermal capacity per unit mass
6)
Conductive resistance
R= d / λ
7)
Thickness associated to node
Δx= d / Ncn
8)
Areal thermal capacity
, per node = ρ c Δx
9)
Conductive resistance
, per node = R / Ncn
10) Air gap --> k=0 ; h(i,e) = 2 ha
ha =
convective-radiative air layer conductance
Also: Thermal transmittance U
shuttered window
curtain wall
Adjacent unconditioned
External
:pen:
corrected thermal resistance of element
Internal
:pen:
temp of unconditioned zone
VENTILATION:
Heat transfer coefficient
PER HOUR
:pen: From
outside
:pen: From
unconditioned space
:pen:
Thermal capacity
of the ztc=
specific t.c. * area
:pen:
Internal/Solar heat gains
:
Overall
In the ztc
:pen:
Solar shading
reduction factor
(Geometry)
:pen:
Extra thermal radiation
to the SKY
:pen: (De-)Humidification load