DIN 4108-2 summer thermal protection

Overview

VICUS Buildings performs the verification of summer thermal protection to DIN 4108-2 using the simulation method: for each activated ventilation variant, a separate NANDRAD simulation project is automatically generated and computed over a full year. From the hourly mean values of the operative room temperature, the excess-temperature degree hours are determined per room and checked against the requirement values of the standard. A PDF report is created for each variant.

Access

The verification page is part of the simulation view: button Simulation in the main toolbar (F10), then in the left-hand list the entry DIN 4108-2. The page is only available in the Building workspace.

Climate location (climate region A/B/C)

Under Current location, the climate region to DIN 4108-2 is chosen: Location A, Location B or Location C. Alternatively, Select location on the map … opens a map of Germany with the three climate regions; a click on the map applies the region.

The choice determines both the climate dataset of the simulation and the reference value of the indoor temperature for the assessment:

Region	Reference climate (test reference year TRY 2011)	Reference value of the operative temperature
A (mild summer)	Rostock-Warnemünde	25 °C
B (moderate)	Potsdam	26 °C
C (hot summer)	Mannheim	27 °C

Independently of the project location, the verification sets fixed boundary conditions: albedo 0.2, latitude/longitude of the respective reference location as well as the European time zone (independent of the project setting).

Ventilation variants

Under Predefined ventilation variants, the variants to be simulated are activated by checkbox; for each activated variant, a separate simulation project is computed and a separate report is created:

Variant	Checkbox	Daytime air change	Nighttime air change
V1	Base air change rate (always active, cannot be deselected)	Residential: 0.5 h⁻¹; Non-residential: 4·A/V	Residential: 0.5 h⁻¹; Non-residential: 0.24 h⁻¹
V2	Daytime ventilation	3 h⁻¹	Base value
V3	Nighttime ventilation	Base value	2 h⁻¹
V4	Increased night ventilation	Base value	5 h⁻¹
V5	Day/night ventilation	3 h⁻¹	2 h⁻¹
V6	Day / increased night air change	3 h⁻¹	5 h⁻¹
V7	Custom (HVAC/custom ventilation)	per-room entry	per-room entry

For non-residential rooms, the base daytime air change is calculated from 4 m³/(m²·h) of outdoor air per m² of floor area, related to the room volume (4·A/V). In the room table, a separate column (V1–V7) appears for each activated variant; a double-click on a ventilation cell opens the dialog Air change rates (ACR) for day/night with the fields Day ACR [1/h]: and Night ACR [1/h]: as well as a weekly preview of the air change rates, in order to adjust values per room.

In the simulation, the base air change is permanently effective. The increased ventilation (window ventilation) is activated in a temperature-controlled way: only when the room temperature lies outside the comfort band (residential 20–23 °C, non-residential 21–23 °C), the outdoor air brings an improvement (e.g. cooler than the room at night) and the wind speed does not exceed 10 m/s.

Room table: assigning residential and non-residential rooms

The verification is only carried out for rooms to which a DIN 4108 room type is assigned. In the room table, rows are selected and typed via the buttons under Assign rooms:

• Residential building — include selected rooms as residential rooms
• Non-residential building — include selected rooms as non-residential rooms
• Remove — remove selected rooms from the verification

The table shows per room: ID, Room, Building, Building level, Usage profile, Type, Cooling load [W/m2], Cooling temperature [C] as well as the air-change columns of the activated variants. Residential and non-residential rooms are highlighted in color (legend Residential building / Non-residential building / No type). Via the expandable Filter area, the table can be restricted by Building name:, Room name:, Zone profile:, Building level name: and Type:.

The columns Cooling load and Cooling temperature optionally allow the consideration of passive cooling: the cooling load must be greater than 0 W/m², the cooling temperature between 0 and 50 °C. Without an entry, the calculation is done without cooling.

For typed rooms, the project generator automatically applies the standard-compliant usage boundary conditions — independently of the room’s assigned usage profile: internal loads of 100 Wh/(m²·d) (residential, evenly distributed) or 144 Wh/(m²·d) (non-residential, Monday–Friday 7 a.m.–6 p.m.) and a heating setpoint temperature of 20 °C (residential) or 21 °C (non-residential). Rooms without a DIN 4108 room type are simulated along with their regular usage profiles but not assessed.

Alternatively, room types can be assigned directly in the 3D scene: button Certification in the mode toolbar, page DIN 4108 room types — there the currently selected rooms are typed via the buttons Residential building, Non-residential building or None, and rooms of a type are selected collectively.

Solar shading

The selection list Solar shading controls how movable solar shading is handled in the verification calculations:

• None — for all rooms of the verification table, any solar shading is ignored, including solar shading elements assigned in the project. Rooms that are not in the verification table keep their project-defined shading control.

• DIN 4108-2 — windows with an assigned solar shading element receive a radiation-controlled standard control with the standard threshold values (activation from irradiance at the facade sensor, hysteresis 50 W/m²):

  Orientation	Residential building	Non-residential building
  N	200 W/m²	150 W/m²
  E | S | W | Horizontal	300 W/m²	200 W/m²

  The reduction factor results from the solar shading element and the actual glazing of the window ($f_{red} = g_{tot}/g$). Windows in rooms without a DIN 4108 room type remain unshaded with this setting.

• Project-defined — the shading controls of the usage profiles stored in the project apply (notice text Uses project-defined shading settings.); the button ↗ opens the database of the solar-shading controls.

Starting the simulation

DIN 4108-2 calculation starts the verification run. Sequence:

1. The project must be saved (otherwise a save prompt appears). On Windows, the path length is additionally checked, since the result paths of the variants are deeply nested.
2. In the dialog Specify DIN 4108-2 output directory, the target folder for the PDF reports is chosen.
3. If result data already exists, the dialog DIN 4108-2 recalculation? asks: Cancel, Use existing data (regenerate the report from existing results) or Re-simulate project. If the data is out of date, re-simulation is recommended.
4. For each activated ventilation variant, a NANDRAD project is generated and simulated (simulation period 1 year, hourly mean values of the operative temperature). The working data is located in the folder <ProjectName>/Certification/DIN4108-2/ next to the project file. Progress is shown; aborts the run.
5. Then the PDF reports are written into the chosen output directory (one report per variant, file name DIN4108-2_<ProjectName>_<Variant>_Report.pdf). If the result data is incomplete or damaged, the report generation is aborted with the message DIN 4108-2 report not created, in order to avoid a misleading verification.

A status label indicates the currency of the results; the check is done via a project hash so that subsequent model changes are detected: DIN 4108 results are not available. / The result data for DIN 4108-2 is out of date. Please re-simulate! / DIN 4108-2 results are up to date.

Assessment: excess-temperature degree hours

For each assessed room, the excess-temperature degree hours are formed from the hourly operative temperature $\theta_{op}$ and the region-dependent reference value $\theta_{b}$ (25/26/27 °C):

$$G = \sum_{h=1}^{8760} \max\left(0,\; \theta_{op,h} - \theta_{b}\right) \cdot 1\,\mathrm{h}$$

For non-residential rooms, only the usage times Monday–Friday, 7 a.m.–6 p.m., are counted. The verification is considered met when the excess-temperature degree hours fall below the limit value:

• Residential buildings: $G < 1200\ \mathrm{Kh/a}$
• Non-residential buildings: $G < 500\ \mathrm{Kh/a}$

Results and reports

The list Generated reports lists the PDF reports of the variants (Double-click to open). Under Report settings:, the checkbox Detailed room information adds additional description pages per room (constructions, windows, shading). Each report contains a title page, table of contents, general information and input parameters, the result list with a pass/fail assessment per room, as well as room preview images from the 3D scene.

Show results switches to the geometry view in the Certification mode; there the page DIN 4108 results provides the evaluation:

• Ventilation: selects the variant to be evaluated.
• Result table with ID, Name, Type, Max. temperature [C] and Excess-temperature degree hours [Kh] (actual value / limit value, green = passed, red = failed) as well as a check symbol per room.
• Color building by excess-temperature degree hours colors the rooms in the 3D scene as a false-color display; Color scale: and Edit legend… adapt the color gradient and value range of the legend.
• After selecting a room, the tabs Carpet plot (hour over month of the operative temperature) and Overview (bar chart of the excess-kelvin hours of all variants with a limit line) show the detailed evaluation.

Related topics

• Solar shading (window components)
• Calculating shading factors
• Starting the simulation
• PDF reports