Monday, May 12, 2014

Creative frugal energy at home

We have various commercial heating sources in our home: woodburner, heat pumps, portable heaters, solar hot water. We are lucky to get a lot of sun exposure. But we also have a natural cold spot in our house; unfortunately it is the bedroom.

In winter, we get 2 hours of a slanted afternoon sunbeam across one far corner of the room before the sun disappears behind the neighbour's house.

Many New Zealand houses like ours are poorly insulated. We go suddenly from "all windows wide open" to "treasure every sunbeam." And it is truly satisfying to set up our homemade sun reflector - made at the end of winter last year and now ready to serve us through a whole cold season.

Sun reflector inspiration

While the bedroom is dark all day, the fence opposite gets all day sun. So close! I knew we must be able to capture that somehow. I favour reuse where possible, so I envisaged hanging an old metal shower tray or several computer cases with some bracing to reflect and direct the light.


Examples of solar reflector designs abound on the internet, but many focus on concentrating sunlight to a point for cooking, which was overengineering for us.

The builder (my husband) is pretty handy and felt my shower tray design was underengineered, so after various experiments and research we reached a suitable compromise (see end of post for full details).

He still wants to automate it to follow the sun. I am OK with resetting it every couple of hours during the day when I can. When it moves off the bedroom window, the ensuite window benefits.


The reflector hanging from the fence is not the most beautiful sight. The most beautiful sight is this warm beam of sunshine (bright enough to show how much our mirror needs cleaning)!

I can have this beauty and warmth from just after 8am until about 4pm.

I still believe in my shower tray design, for those of us without a master builder on tap.

But I also hope that more examples of what has been done will inspire more of us to try what works in our own environment.

Reflector Details (from the builder)

Board materials and Assembly

  • Chrome Vinyl wrap (used on cars or signwriting)
  • Coreflute board
  • six 40mm x 18mm x 1.2m plank for framing support for coreflute board
  • surefix screws
  • staples + staplegun

  1. Create a frame to support the coreflute board
  2. Staple the coreflute board to the frame
  3. Cover the coreflute board with the chrome vinyl wrap

Mounting materials and assembly
  • 45 x 90 x 1500 H3 post
  • 2 x "Gate hinge pin and strap"
  • 1 x 150 x 25 x 1500 fence board
  1. Attach the post to a fence with spacing to allow the reflector board to rotate
  2. Install the hinge pins into the post ~1m  apart
  3. Put the hinge strap on the pins
  4. Mark one fence board to attach the gate straps at the correct spacing
  5. Remove straps from pins and attach to fence board

Tilt materials and assembly

  • 2 x 150 x 25 x 1500 fence board
  • 2 x "garden Gate hinges
  • Bolts and screws to suit

  1. Attach a fence board to the fence board of the mounting to make the top of a "T"
  2. Use the 2 x garden gate hinge to attach the third fence board to the top of the "t"
  3. Lift the tilt assembly onto the mounting post gate hinge pins to test fit and remove.
  4. Attach the reflector board to the third board.
  5. Lift the assembly onto the mounting post gate hinge pins to test fit.

Tilt stay materials and assembly

  • length of aluminium flat 15mm x 4mm
  • two 20mm right angle bracket
  • 15mm M3 or M4 bolt and 2xnuts (or 1 x nylock) and washers
  • Stay clamp
  • Captive nut and bolt
  • piece of wood to mount the captive nut
  • washers for spacing the mount from the

  1. Cut flat bar to length
  2. Round one end of the bar and drill 3mm/ 4mm hole for bolt in same end 
  3. Attach right-angle brackets to back of reflector with space between for Stay
  4. Attach stay to the brackets with the bolt and nuts
  5. Drill hole in piece of wood to suit captive nut and bolt 
  6. Insert captive nut
  7. Install piece of wood on edge of upright of the tilt mounting, using screws at each end with washers to provide space for the stay to pass through. Ensure the gap between the washers allows for the stay to rotate, but not so large that the bolt that holds the stay cannot clamp the stay.
A similar stay assembly can be used for the yaw stay

1 comment:

  1. Bloody brilliant. Don't let someone steal intellectual property.