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

🖊 Mean radiant temp=
Average of internal temp of each elements
weighted on its area

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

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

🖊 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

🖊

  • 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

🖊

  • 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

Calculation procedure

🖊 Thermal bridges
Overall heat transfer coefficient
H = Σ ( l Ψ ),
l: lengh ; Ψ: linear thermal trasmittance

Energy balance bld Element

🖊

  • moisture load
  • latent H load

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

Opaque/Internal partition -->
2 on surfaces + 3 inside

Touching the ground -->
ext heat transfer coeff =
thermal conductance of ground layer

Windows/Doors --> 2

ISO 52016-1

Italian National Annex

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)

Areal heat capacity k:
very light -- very heavy
no mass component -- > 12 cm bricks/concrete

  • I --> k5=km
  • E --> k1=km
  • IE --> k1=k5=km/2
  • D --> k1=k5=k/8 ; k2,3,4=km/4
  • M --> k3=km

1) 🖊 Fourier number, each layer
2) Fo(ref)=0,5
3) 🖊 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

h = 1 / R

ISO 13789:
--> Area, Thermal resistance

ISO 13789 + 13370:

  • Area ; Virtual ground temperature
  • Floor effective thermal resistance (considering Ground)
  • R & k of 0,5 ground layer

Also: Thermal transmittance U

  • shuttered window
  • curtain wall

Adjacent unconditioned

External
🖊 corrected thermal resistance of element

Internal
🖊 temp of unconditioned zone

VENTILATION:

  • Heat transfer coefficient
    PER HOUR

🖊 From outside
🖊 From unconditioned space

🖊 Thermal capacity of the ztc=
specific t.c. * area

🖊 Internal/Solar heat gains:

  • Overall
  • In the ztc

🖊 Solar shading
reduction factor
(Geometry)

🖊 Extra thermal radiation
to the SKY

🖊 (De-)Humidification load