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Wim PlokkerMSc Applied PhysicsVABI Software b.v.Project leader EN ISO 52010w.plokker@vabi.nl | Dick van Dijk MSc Applied PhysicsEPB-research –The NetherlandsEPB-research@dickvandijk.nl |
EN ISO 52010-1
[1], accompanied by the technical report CEN ISO/TR ISO 52010-2 [2],
provides the common standard climatic data to be used for all relevant EPB
standards. It gives procedures to calculate the hourly distribution of solar
irradiation on a non-horizontal plane based on measured hourly solar radiation
data on a horizontal surface, obtained from EN ISO 15927 (part 1,
2 and 4) [3].The calculation procedure described in this standard is based on the widely
used “simplified Perez model” [4] proposed in the early 90’s.
The procedures include assumptions to assess
the impact of surrounding obstacles on the irradiation (shading). A simple
method for conversion of hourly solar irradiance to illuminance is provided.
The
technical report CEN ISO/TR ISO 52010-2 provides background information,
explanation (including examples) and justification (including validation cases).
The main
output from EN ISO 52010-1 is the solar
irradiance and illuminance on a surface with arbitrary orientation and tilt, needed
as input for energy and daylighting calculations.
Shading by
distant objects is (optionally) taken into account through a shading correction
coefficient, Shading by fins and overhangs is calculated in EN ISO 52016-1
[5].
The standard contains procedures for the use of (other) output from EN ISO 15927
(part 1, 2, and 4) [3] as input for the EPB assessment,
such as:
·
air temperature;
·
atmospheric humidity;
·
wind speed;
·
precipitation;
·
solar radiation;
·
longwave radiation.
The reason for passing these data via this
standard is to have one single and consistent source for all EPB standards and
to enable any conversion or other treatment if needed for specific application.
In line with the common template for all EPB
standards, a spreadsheet has been prepared for demonstration and validation.
This spreadsheet shows an overview of all input variables, the (step by step)
hourly calculation procedures and an overview of all output variables.
This accompanying calculation spreadsheet
(July 2016) provides:
·
full year of hourly calculations
of solar irradiance (split in components) on a plane with any azimuth and tilt
angle;
·
validated against BESTEST cases;
·
hourly calculations of solar
shading by multiple shading objects along the skyline. These calculations also
cover the calculation procedures for overhangs from EN ISO 52016 1 [5];
see parallel article Van Dijk on EN ISO 52016 & EN ISO 52017.
Options for national choices provided in
“Annex A/Annex B” of EN ISO 52010-1 comprise:
·
Selection of hourly measured
climatic data set.
·
Different choices of type of
measured irradiation, depending on availability.
·
Value(s) for ground reflectivity.
·
Include or exclude impact of solar
shading by external objects. If excluded: the solar shading calculation is done
in application standards, such as EN ISO 52016-1, enabling to
calculate the impact of all shading objects in a coherent way without
duplications. If included: a choice is given between different levels of
detail.
·
Choice between the given
simplified Illuminance calculation method or alternative methods.
The calculation procedures have been validated
by using relevant cases from the so called BESTEST series. The BESTEST cases
are well established since decades, widely used worldwide and well described.
More background information is given in the technical report, CEN ISO/TR 52010-2.
Relevant BESTEST cases are also chosen for the validation of the hourly
calculation procedures of EN ISO 52016-1, as presented in the
parallel article (see also previous article [6]).
Figures 1-3 show examples of the results of the validation cases. The validation
cases concern the hourly calculation of the solar irradiation at vertical
planes, using the measured data from a given climate data file.
Figure 1. BESTEST validation result: Hourly
irradiation on vertical West plane, cloudy day.
Figure 2. BESTEST validation result: Hourly
irradiation on vertical South plane, clear day.
Figure 3. BESTEST validation result: Annual
solar radiation on five different planes.
The results of the comparison show that the
method in EN ISO 52010-1 is very fit for purpose. It has to be taken
into consideration that not each software program whose results are available
for the comparison use nowadays state-of-the-art algorithms (in that sense
these are not reference results). This is because these base cases of the
BESTEST series were created and tested many years ago.
More tests are
described in the technical report, CEN ISO/TR 52010-2.
The new EN ISO 52010-1
completes the (until now) missing link in the conversion of climatic data for energy
calculations. The procedures have been validated. Choices are possible at
national or regional level to accommodate the specific national or regional
situation.
The authors would like to acknowledge specifically
the contributions of the other experts in the team that is responsible for the
preparation of EN ISO 52010, especially José L. Molina
(Universidad de Sevilla, Spain) and Francisco José Sánchez de la Flor
(Universidad de Cádiz, Spain) who developed the solar shading calculation procedures for
EN ISO 52010 and EN ISO 52016.
[1] EN ISO 52010-1,
Energy performance of buildings — External climatic conditions — Part 1:
Conversion of climatic data for energy calculations.
[2] CEN ISO/TR 52010-2,
Energy performance of buildings — External climatic conditions — Part 2:
Explanation and justification.
[3] EN ISO 15927-1 to 6, Hygrothermal performance of
buildings – Calculation and presentation of climatic data – Parts 1 to 6.
[4] Perez, R.; Ineichen, P.; Seals, R.; Michalsky, J.; Stewart, R.
(1990). “Modeling Daylight Availability and Irradiance
Components from Direct and Global Irradiance.” Solar Energy, 44(5), pp.
271-289.
[5] EN ISO 52016 1, Energy performance of buildings – Energy
needs for heating and cooling, internal temperatures and sensible and latent
heat loads – Part 1: Calculation.
[6] Wim Plokker & Dick van Dijk, EPB standard EN ISO 52010:
Conversion of climatic data for energy calculations: completion of a missing
link, The REHVA European HVAC Journal, Volume 53, Issue 3, May 2016.
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