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Energy balance in building image EPBD (Energy Performance of Buildings…
Energy balance in building
EPBD (
Energy Performance of Buildings Directive
) 2002/91/CE
Goal: improve energy performance of buildings in the European Union
Standards
Italy: Energy balance
on Indoor Air, influenced by
(steady state)
Qh>0 in winter time, when heating system is needed
Qh<0 & Qc=-Qh in summer time, when cooling is needed
Climate
Air infiltration
Wind
Affected by the roughness of the ground
Solar Heat gains
Solar radiation
Convective surface heat transfer
Radiative surface heat transfer
Atmospheric radiation
for lambda<8 micrometri lambda>13 micrometri, the atmosphere reflects the terrrestrial radiation and it can be expressed as a function of
air temperature
#
or with the
apparent sky temperature
, i.e. the temperature that the atmosphere would have if it were a black body
Ventilation enthalpy flow (
latent
)
Air Humidity and HR
Temperature difference (
sensible
)
Air temperature
it depends on solar radiation but also on the ground heating and on the meteo conditions (clouds ecc)
Design
Heating
Outdoor air Temperature
Extreme (
design
) winter temperature
used to design the heating system
Frequency distribution
Temperature that is overtaken 99% of time, over the past 20 years, during the coldest months
Dynamic energy balance
Temperature which leads, in the coldest period, to the minimum acceptable final indoor temperature below set-point
Cooling
Clear sky radiation
Air temperature daily time trend
Air relative Humidity
Simulation
Heating and cooling degree-days (
calculations by hand
)
Average monthly solar irradiation and air temperatures (
simplified
)
Test Reference Year (
dynamic model
)
Energy demand
Component
