Roof Blinds for Skylight Windows

With work on the Outbuildings progressing, it will only be a few months until those provide a large Workshop space which will replace the current use of Bedroom 5 on the Second Floor of the House, which has been temporarily acting as a workshop and ‘shed’. It’s therefore a good time to start preparing for that being used as a bedroom; up until recently little had been done since it was first built and the walls and ceiling were still bare plaster.

Natural lighting for Bedroom 5 comes from two fixed skylight windows deeply recessed into the ceiling which slopes at 11 degrees to the horizontal. They’re tilted towards the North but with them being so nearly horizontal they do receive direct sunlight in the summer months, which can tend to make this room a bit too warm. These windows therefore want ‘blackout’ blinds which exclude enough light for sleeping in this bedroom and which can also be used to block out the summer sun.

Many of the available skylight blinds are designed to be fitted to the wooden frame of opening roof windows from VELUX and similar window manufacturers, where the blind needs to move with the window when that opens and closes. Those are a good solution where the window opens and where they are relatively accessible – such as in a loft conversion. However, they’re not suitable for this installation.

As with all the other ‘windows’ in the House, these skylight locations were wired back to KNX-managed relay controls for 230V electric blind motors, using three-core-and-earth cabling. All but one of the other windows have electric roller blinds (the exception has an electric vertical blind) which rely on gravity and a metal hem bar to operate. With these windows being so close to horizontal, roller blinds need ‘help’ to close – and to stop them sagging.

Previous research to find suitable blinds had failed to identify a good solution. The closest match is blind systems used for genuinely-horizontal ‘roof lights’ or ‘roof lanterns’. Some roof light blinds use ‘honeycomb’ fabric and low-voltage motors and radio controls, which would complicate the automation compared with a simple 230V motor and relay control. Other systems designed for (much) larger roof lanterns had minimum sizes which were slightly too large for these relatively modest skylight openings.

In the end I settled on the Helios RL Wire-guided rooflight system from Umbra Shading for which there is a good range of technical resources explaining how they work. In broad terms, these use spring-loaded wire spools to apply tension to the blind fabric and to pull it down as the motor unwinds. Local installer Butterley Barn Interiors supplied and installed Helios RL blinds with enclosed top and bottom boxes to conceal the roller tube and spring boxes.

Umbra Shading Helios RL blind in sloping ceiling of Bedroom 5

There’s a bit of a gap at each side of the blind, where the guide wires are. For an even better blackout effect that could be covered with an angle-section trim strip

Motorised Vertical Blind

The window in the office on the second floor is large (5.5 m^2) and directly west-facing. It’s a nice feature and provides a great view but it does let the evening sun in which tends to overheat the office on the hotter days of the year. The answer is some shading. External shading is more effective than internal at keeping heat out and it might be sensible to add some fixed external shading in due course but for now I’m going to fit an internal blind and see how much of a difference that makes.

One complication is that the top of the window follows the line of the north roof, which slopes at 12 degrees and means normal roller blinds (as fitted to the other windows) won’t work. A “bottom up” roller blind might have done the job but I settled on a vertical blind with slats of differing lengths that stack on the tall side of the window. Something that proved more complicated than I was expecting was arranging for motorised control – I want to be able to close the blind automatically based on the time of day, the temperature and the amount of sunshine.

All of the windows have a connection point at one of the top corners for an electric blind, with a 3-core & earth cable which runs back to a control unit. For most blinds this is fine – the 3 cores are used for Neutral, Live #1 (Up) and Live #2 (Down). However, my chosen brand of vertical blind motor wanted a permanent live as well as two switching cables, requiring a 4-core & earth cable. I briefly considered running a different / extra cable but then decided to pursue other options.

In general I’m not a fan of radio control since in the past I’ve had issues with devices only working intermittently but it seemed like the least-bad way to go in this case. The Benthin IQ2 motor recommended by my blind supplier works with the Somfy RTS radio control standard and for manual control this works very well with a hand-held transmitter. For remote or automated control things are a bit more complex but the RFXtrx433E USB HA controller from RFXCOM supports the Somfy RTS protocol and is also supported by OpenHAB, my chosen home automation software. Using one of those also allows me to retire my old RFXCOM receiver which is listening for temperature and humidity messages from a range of Oregon Scientific indoor environment sensors.

Vertical blind installed in office window

Vertical blind in office window – fully open