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Good morning
I’m Professor Colin Porteous from the
Mackintosh Environmental Architecture Research Unit
and I’m going to speak in this slot about a project
that was completed 15 years ago,
the Easthall solar demonstration project,
and indeed helped set the research unit MEARU
up at that time in the early 1990s,
with the particular theme of how close it could get to zero carbon today.
In order to make a start on the zero carbon theme,
the first thing is to try and define zero carbon.
In Scotland, the Sullivan Report of 2007 defined
levels of carbon emissions relative to the Scottish
technical standards of that same year.
So, they had low carbon set at 30% of the 2007 standards,
very low carbon at 60%,
and finally total life zero carbon,
which as the name suggests,
got to 100% relative to the technical standards
but also included embodied energy,
just to make matters slightly more complicated.
The regulated energy standards to which it was
referring in the Scottish Technical Standards of that year,
relate to space heating, water heating and lighting,
and any fans, pumps etc associated with ventilation.
So, it’s not the whole of the energy involved in the building,
and indeed the total-life zero carbon,
which rather implies that everything is taken into account,
takes into account effectively what the building uses,
rather than the people inside the building.
So, it excludes all the power use in terms of washing machines,
dishwashers and so on.
On the other hand,
the UK-wide definition of Zero Carbon by
Her Majesty’s Revenue & Customs
includes all that additional power use.
So, when they mean Zero Carbon it’s something
quite different from the Sullivan Report.
And, the HMRC definition is in turn aligned
with the Department of Communities and Local Government,
applicable in England and Wales.
And, in each case the requirement is essentially
that all the generation renewably occurs on the site
- the only softening of that position being to allow private wire arrangements.
Just to put this into a European context,
the HMRC and the
Department of Communities & Local Government definitions
seem to align relatively closely
with the German ”Zero Haus” definition of zero carbon.
German “Zero Haus” is essentially PassivHaus Plus.
PassivHaus required total primary energy consumption including everything,
all power use of no more than 120 kilowatt hours/m2/annum.
Zero Haus has lowered that to 100 kilowatt hours /m2/annum.
So, it’s 20% more stringent,
but the key thing about the Zero Haus as supposed to PassivHaus
is that it requires net-zero carbon emissions over the year.
So, having set the scene in relation to what we’re
talking about in zero-carbon,
the aim here is to look at what Easthall achieved and
to see whether it could achieve zero carbon in terms of the Scottish standards,
in terms of the Sullivan Report.
In summary, the Easthall project achieved taking
sub-standard 1960’s housing stock out of fuel poverty
and in doing so it made use,
of course, of upgrading insulation, upgrading heating,
but it also made use of both passive and active solar heating techniques.
If we go, first of all, to the condition of the houses beforehand,
the construction looks traditional
traditional pitched tiled roofs, traditional walls,
but in fact the construction of the walls was non-traditional.
And, it was a special block called a Wilson block.
That particular Wilson block,
which we can look at on this slide,
comprised 2 very thin skins joined together in each block by 3 ties.
The heat loss through this block was remarkably high,
a U value of approximately 2.5 Watts /m2K.
Now, one might compare that with a traditional
masonry building of the beginning of the 20th century of about 1,
so it was something like 2 ½ times greater
than a traditional masonry tenement.
So, fuel poverty was an acute issue and the
position adopted was to divide that rate of heat loss by 10.
On the right-hand side of the slide you can see
the cavity itself filled with insulation,
but over and above that there’s external insulation
on the outside of the wall.
The external insulation gets over the problem of any
cold bridging that would still have occurred through the ties in each block.
So, looking at the whole picture,
Easthall was derived from a competition and this was
a drawing by one of the participants of that competition,
John Gilbert Architects.
We can see that the house comprised a living room,
main bedroom, smaller bedroom,
bathroom & kitchen.
The external walls were of course relatively easy to
insulate in the manner shown.
But, there were special conditions
- there was a wall to the stairway entrance,
that was a cavity brick wall,
that was cavity insulated.
There was a single skin of brick wall to a
store which was unheated in this location,
and that had to be internally insulated.
So, it wasn’t just simply a matter of the insulated
construction to the external wall.
The insulation had to take account of very specific circumstances.
And then, the existing open balconies or verandas
were an obvious target to glaze in and make into a glazed buffer space.
And, on the other side of the house,
the opportunity was taken to expand the very small
kitchen area into a utility space which was again a glazed space.
The issue, of course,
with housing of this age is that the orientation
is pre-determined in all directions.
So, it might be that the particular veranda faced due west,
or it might be faced due east,
or it might even face due north.
Or, it could, of course, face south.
But, having a glazed buffer space in each side of the
building actually took account of all orientations
in a reasonably satisfactory manner.
Over and above insulation and the glazed spaces,
which predominantly are helping in terms of,
one could call it ‘edge insulation’,
but the other way to look at it is looking at the
ability to pre-heat air for ventilation so that
air coming into this bedroom,
for example, is pre-heated in that space between
the bedroom and the outside,
and therefore cuts down on the ventilation load.
Similarly, air entering the kitchen,
which will be fairly rapidly exhausted,
but it’s still, instead of taking air at ambient temperature,
it’s taking air at the temperature of the buffer
space before it reaches the kitchen.
And, in the same way, air can be taken from the veranda space,
glazed veranda space,
via a French window into the living space rather
than through the direct window.
Over and above all that,
we see here the initial sketch ideas,
not finally as built,
but the initial sketch ideas for a solar air collector
built into the roof and also a vertical air-collector
built into this wall.
Well, what were the pitfalls of what was achieved here?
If we were doing it today,
the first thing we wouldn’t do is do the space-heating
as was done then.
That point in time,
the tenants’ prime concern was to have a full central heating system.
Actually, because we were insulating to quite a high standard,
we could have probably got away with a partial
central heating system but that simply wouldn’t
have been politically acceptable.
The other thing was that,
again at that point in time,
in the early 1990s,
tenants still wanted to have a focus-fire.
And, some of them already had gas fires in the central chimney stack.
The logical thing seemed to address gas central heating,
not with a modern condensing combi-boiler,
but at that time with a radiant fire with its own
back-boiler and that served the existing hot water
cylinder which is located in a cupboard directly
next to the chimney.
The problem with that is that a) the boiler has a very
low efficiency compared with a modern condensing boiler,
and b) it required a permanent air supply,
effectively a hole in the wall.
And so, not only was the heating system less efficient than
one could achieve today,
the rate of ventilation was also a good deal higher
than would be required if one had had a combi-boiler
located either in the utility space or in the kitchen.
So that was a significant weak link.
The other weak link was the fact that we only used
standard double glazing to the main window in the
living room and also the small window in the small bedroom.