VDI 3789 Blatt-2 1994-10 PDF

Full title and description

STB VDI 3789 Blatt-2 1994-10 — Umweltmeteorologie / Environmental meteorology — Wechselwirkungen zwischen Atmosphäre und Oberflächen / Interactions between atmosphere and surfaces — Berechnung der kurz- und der langwelligen Strahlung / Calculation of short‑wave and long‑wave radiation. This document (VDI 3789 Blatt 2, Part 2) gives methods to calculate integral short‑wave and long‑wave radiant flux densities for arbitrarily oriented surfaces, accounting for atmospheric effects, surface optical properties and horizon obstruction.

Abstract

Provides calculation procedures for the irradiance (short‑wave and long‑wave) received by surfaces of arbitrary orientation. Topics include the influence of time of day and year, atmospheric attenuation (Linke turbidity), surface properties (albedo, effective long‑wave emissivity/transmissivity), and geometric effects such as horizon shading and sky view. The standard was published in German and English and contains technical appendices with supporting factors and conversion formulas.

General information

• Status: Withdrawn / Superseded (replaced by VDI 3789:2019‑04).
• Publication date: 1994‑10 (October 1994).
• Publisher: Verlag des Vereins Deutscher Ingenieure (VDI‑Verlag).
• ICS / categories: 07.060, 13.040.01 (environmental meteorology / building physics).
• Edition / version: VDI 3789 Blatt 2 (Part 2), 1994‑10; bilingual (German / English).
• Number of pages: 52 pages.

Scope

Specifies methods to compute the short‑wave (solar) and long‑wave (thermal) radiant flux densities incident on surfaces with arbitrary orientation under a range of atmospheric and sky conditions. It treats clear and overcast conditions (hourly averages for cloudy skies), includes adjustments for surface optical properties (albedo, emissivity, transmittance), and accounts for horizon limitations and sky obstruction. Appendices provide practical routines for Linke turbidity, optical air mass and conversion between statutory and local time.

Key topics and requirements

• Symbols, definitions and notation for radiant flux densities and surface orientation.
• Calculation method for short‑wave (solar) irradiance on arbitrarily oriented surfaces (direct + diffuse components).
• Calculation method for long‑wave (thermal) irradiance taking atmospheric and surface emissivity into account.
• Influence of surface optical properties: short‑wave albedo, effective long‑wave emissivity, and transmittance.
• Corrections for horizon obstruction, sky view factor and geometric shading.
• Appendices with Linke turbidity factor, optical air mass & vertical optical thickness, and time conversion formulas.

Typical use and users

Used by environmental meteorologists, climatologists, building physicists, solar energy engineers, urban climate consultants, architects and researchers who need standardized methods to estimate radiation loads on surfaces (façades, roofs, sensors, solar collectors) for design, simulation and assessment tasks. National/regional adoption copies (e.g., STB‑prefixed listings) may appear in some catalogues and document repositories.

Related standards

Replaced by VDI 3789:2019‑04 (Environmental meteorology — Calculation of spectral short‑wave and long‑wave radiation), which consolidates and extends earlier Blatt documents including Blatt 2 and Blatt 3. Other items in the VDI 3789 series (e.g., Blatt 3:2001) and adjacent building‑physics and solar measurement standards are related references when implementing spectral or advanced radiative transfer methods.

Keywords

short‑wave radiation, long‑wave radiation, irradiance, albedo, emissivity, Linke turbidity, optical air mass, surface–atmosphere interaction, horizon shading, VDI 3789, environmental meteorology.

FAQ

Q: What is this standard?

A: VDI 3789 Blatt 2 (1994‑10) is a VDI technical guideline that defines calculation procedures for short‑wave and long‑wave radiant flux densities on arbitrarily oriented surfaces, published in German and English.

Q: What does it cover?

A: It covers the mathematical procedures and practical factors required to compute solar (short‑wave) and thermal (long‑wave) irradiance on surfaces, including atmospheric attenuation (e.g., Linke turbidity), surface optical properties, and geometric effects such as horizon obstruction and sky view. Appendices supply supporting formulas (optical air mass, time conversions).

Q: Who typically uses it?

A: Practitioners in environmental meteorology, solar energy, building physics, urban climate studies, architects and consultants who perform radiation load calculations or simulate thermal and solar performance of surfaces.

Q: Is it current or superseded?

A: Superseded. VDI 3789 Blatt 2:1994‑10 was withdrawn and replaced by VDI 3789:2019‑04 (published April 2019), which provides updated and spectral calculation methods and integrates material from earlier Blatt documents.

Q: Is it part of a series?

A: Yes — it is Part 2 (Blatt 2) of the VDI 3789 series on environmental meteorology and surface–atmosphere interactions. The 2019 consolidated VDI 3789 revision supersedes several Blatt items.

Q: What are the key keywords?

A: Short‑wave radiation, long‑wave radiation, irradiance, albedo, emissivity, Linke turbidity, optical air mass, surface–atmosphere interaction, horizon shading.