2002 MAWSON RETRO 6 – vertical axis Heliostat

Largely made from re-used ‘scrap’ panels of 0.7mm polished stainless steel, the sculptural quality of the heliostat has been a major factor in its success. The reverse side is barely visible from the road, being well covered by the evergreen vine.

The functional loss of solar energy on the functional side is tolerated. Note how the reflected images tend to make the heliostat disappear.

While the flat plate reflectors (see Retro 5) are good value for money they are not as fully effective as they might be, in that the reflected image traverses the room from west to east and the early morning and late afternoon images do not fully enter the room.

I designed the heliostat reflector to overcome that disadvantage and in addition to put the full reflected image into the receiving window at 90º for the full sunlit period by having a rotation that followed the sun (1.875º/15 min).

The mirrors are of roughly the same area as the window and rotate from approx. 7am to approx. 5pm, returning automatically to the 7am position. The whole panel can be adjusted manually between early winter and mid winter for greater efficiency.

I had considerable voluntary assistance from 3 colleagues – Ray Franzi who calculated the wind stresses and structural dimensions, late Richard Saberton who designed and machined the winch and rotation system and David Anderson who designed and made the electronic timing system and who has continued to this day(2016). Although it has had several teething troubles in matching the electronics to the mechanics it has nevertheless justified the effort and has, as a working prototype, worked extremely well for 13 winters.

It is a useful sculpture and has received much comment for achieving that aim and now that the evergreen vine on the road side of the sculpture has grown effectively it is now appeasing the early criticism I received from one or two members of the Body Corporate.

Would I do it again ? With the benefit of hindsight – probably yes, with certain modifications – but not in my lifetime. It is most likely the first such reflector in the world and David and I have learned a lot – we now know what NOT to do next time. If I may be allowed to say so the concept is brilliant but it was a research exercise to test an idea, and it needs a Mk 2 simplification to improve reliability. This is continuing.

The CHP model (MR 9) is what I would choose as a commercial model as it has the capacity of being useful for 12 months of the year and hence is better value for money, even though it costs more.

1(see also 10 commissioned flat plate arrays – Kral 2002, MacPherson 2002, Fenner 2008, Edwards 2008, Maindonald 2009, Pipitone 2010, Ecob 2011, Suttle 2013, Wootten 2014 but only 2 were charged a fee)

6 others were requested and analysed but did not proceed for physical or financial reasons.

Comment

My architecture has, by virtue of life’s circumstances, turned to a belief that Canberra’s architecture really needs rescuing from itself.

As about 95% of tomorrow’s houses are already built (usually with little consideration for solar gain) there is a huge need for low-energy retrofitting if we are to beat climate change.

This prototype heliostat reflects over 4 sq.m. of sunlight through our southern dining room window at 90º for all sunlit hours pouring about 10kWh of free heat at 90º into the house from April to September.

Add to that the psychological or therapeutic effect of sunlight upon the jaded mind accustomed to cold, sunless southern rooms and the occupant is cheered and rejuvenated.  There is more – such a room is now elevated to a position of usefulness – being cheerful, inviting and warm, thereby making the house that much bigger.

Every northern and southern room in our ‘developer’s’ house is now sunlit for most of a sunny winter’s day.

wrigley-dr This is all borrowed sunlight from the heliostat – at 90º to the window during all sunlight hours

Imagine a new house in which the windows and reflectors on the south side do exactly the same as those on the northern side – every room is then cheerful, warm and useful, which turns previous architectural deficits into benefits.

The automated heliostat was, however, a singular prototype. The simple concept has now been  re-designed to be even simpler.  It is now a manual, repeatable model capable of similar efficiency and at lower cost.

This turns 21st century housing into thoughtful architecture, contributing to real solar, sustainable living in which a conservative 40% less-than-effective internal space can be returned to effective, enjoyable usefulness.

This concept uses sunlight that is additional to a house’s solar right and is only one part of the EcoSolar Housing System which returns significant amounts of wasted resource potential to effective usefulness, making a significant contribution to reversing the downward spiral of climate change.

We are well on the way to producing a house with no resource bills – indeed in Jan 2016 I checked my electricity bill and calculated that with 5kW of PVs on the roof + reflectors we were generating 6.4 x more electricity than we were using over the spring account period of 2015 – Sept,Oct,Nov.) .(check elec. a/c issued19 Jan 2016).

Midwinter rotations plan 9.6.02 v2008

While the flat plate reflectors (see Retro 5) are good value for money they are not as fully effective as they might be, in that the reflected image traverses the room from west to east and the early morning and late afternoon images do not fully enter the room.

I designed the heliostat reflector to overcome that disadvantage and in addition to put the full reflected image into the receiving window at 90º for the full sunlit period by having a rotation that followed the sun (1.875º/15 min).

The mirrors are of roughly the same area as the window and rotate from approx. 7am to approx. 5pm, returning automatically to the 7am position. The whole panel can be adjusted manually between early winter and mid winter for greater efficiency.

I had considerable voluntary assistance from 3 colleagues – Ray Franzi who calculated the wind stresses and structural dimensions, late Richard Saberton who designed and machined the winch and rotation system and David Anderson who designed and made the electronic timing system and who has continued to this day(2016). Although it has had several teething troubles in matching the electronics to the mechanics it has nevertheless justified the effort and has, as a working prototype, worked extremely well for 13 winters.

It is a useful sculpture and has received much comment for achieving that aim and now that the evergreen vine on the road side of the sculpture has grown effectively it is now appeasing the early criticism I received from one or two members of the Body Corporate.

Would I do it again ? With the benefit of hindsight – probably yes, with certain modifications – but not in my lifetime. It is most likely the first such reflector in the world and David and I have learned a lot – we now know what NOT to do next time. If I may be allowed to say so the concept is brilliant but it was a research exercise to test an idea, and it needs a Mk 2 simplification to improve reliability. This is continuing.

The CHP model (MR 9) is what I would choose as a commercial model as it has the capacity of being useful for 12 months of the year and hence is better value for money, even though it costs more.

1(see also 10 commissioned flat plate arrays – Kral 2002, MacPherson 2002, Fenner 2008, Edwards 2008, Maindonald 2009, Pipitone 2010, Ecob 2011, Suttle 2013, Wootten 2014 but only 2 were charged a fee)

6 others were requested and analysed but did not proceed for physical or financial reasons.

Final elev.

It would most appropriate to pay tribute to the supportive work that Richard Saberton made to many of my activities – in this instance to the detailed design work he contributed to my basic concept of the heliostat. The height adjustable weight in the column, the windlass concept, the turning of the winding drum on my lathe was all his work. He was a fully trained fitter and turner as well as a mechanical engineer and his death in the early 2000s was a severe blow to me and to his many friends around Canberra.

His extensive work in Technical Aid to the Disabled ACT helped many of our volunteers to develop their projects and he was always available to help anybody. He was born in Peterborough, UK and we became firm friends through our TADACT and solar research work.

His engineering input to the LIFT-CARE height adjustable bed during the 1980s made my original concept really work so beautifully – see entry in DISABILITY segment.

Richard was also a part-time lecturer at the School of Mechanical Engineering at Bruce TAFE for many years.

2000-richard-saberton

Richard and Derek at Bruce TAFE after a discussion on the LIFT-CARE bed – about 1990