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The 3rd house type that we look at
was the 8-storey Byson Towers,
constructed again in the 60s,
but this time from precast concrete sandwich panels.
MEARU proposed these to be insulated
externally as they were already insulated internally.
The windows would be replaced to a
2007 norm and to have balconies glazed in.
There is a case to be made for complete
encapsulation of the existing rectangular form of the block.
Adding an extra 100mm insulation over opaque surfaces,
glazing in the balconies and slots,
and replacing existing windows.
This would reduce thermal transmittance through
the outer main walls significantly.
Analysis shows that the significant upgrades to insulation,
together with replacement and addition of
windows will reduce the thermal load to a
level of viability for a CHP system,
but one that might need further integration
of electrical generation.
In this case, roof-integrated wind turbines
could supply such a shortfall.
The estimated space heating load of an externally
insulated 2-apartment flat is 1173 kilowatt hours,
72% less than existing.
This corresponds to a SAP value which would be 78,
as opposed to 52 as existing.
As Cube had indicated a reluctance to external insulation,
a fall-back scenario, omitting this insulation was considered,
but instead only replacing windows,
glazing in balconies and improving ventilation.
This again means replacing the two electric storage
heaters in each flat with a CHP system.
For this fall-back scenario,
space-heating loads meet 2200 kilowatt hours,
48% less than existing and a corresponding SAP value of 77.
This proves that the lack of external insulation
only marginally affects the ratings.
Although not yet cost-planned,
the range of fabric upgrade measures proposed for
these high-rises are likely to be affordable given appropriate phasing.
In summary, these upgrades to most of the
house-types include a combination of internal insulation,
cavity insulation, and potentially external insulation,
new windows, if they could be justified,
glazed in balconies and improved ventilation.
This is a minimal option open to Cube Housing Association,
which remains reliant on grid electricity,
and conforms to the Scottish Housing Quality Standard.
However, simply upgrading the fabric without renewing the
heating will not meet the housing quality
standard in terms of SAP ratings,
while upgrading the fabric with grid-connected
electric heating will not significantly address carbon reduction.
Measures to move towards CO2 neutrality aided by
major CHP plant should be considered as a
longer term energy efficient solution.
Due to the existing vertical servicing in all the high-rises,
this seems feasible without significant
disruption to existing internal fabric.
Assuming capital affordability,
there’s a viable case for biomass
gasification CHP for the high-rises,
and based on the predictions for heat and electricity demands.
The provision of more efficient methods of
meeting communal lighting and lift loads
could comprise a combination of several options.
Using electricity generated from CHP,
depending on the heat-to-power balance
at different times of the year,
buying into one or more relatively
large and remotely-sited wind turbines,
on-site renewable sources such as
building-integrated photovoltaic arrays,
andor building integrated wind generators.
Such a combination of systems would take all
the high-rises close to carbon neutrality.
Ironically, easier to achieve than
for a low-energy new-build equivalent.
Through the examination of each of the three house types,
we have looked at the before and after
SAP rating and compared the annual energy load.
However, this table converts these values to
an energy consumption value per m2 in order
to make a direct comparison with the PassivHaus standard.
This analysis assumes a heating season
from September to May,
hot water and electricity for cooking,
lighting and appliances will remain unchanged
in the now and proposed scenarios.
The final role gives values where notional flat
of 80 m2 conforming to the Scottish Technical Standards 2007,
together with the upper limit for space heating
in a dwelling to the German PassivHaus standard.
This shows that not only do the proposals suggested in
this study meet Scottish Housing Quality Standards,
some proposals actually meet current building regulations.
Indeed, some scenarios move closer to the
PassivHaus standard of 15 kilowatt hours/m2 for space heating,
and in addition to the proposed biomass CHP system
would significantly address carbon reduction,
helping to meet the Government’s 80% target by 2050.
As noted at the start of this presentation,
given the variety in building types in the social housing stock,
there is certainly no “one size fits all” approach to existing homes.
As explored in Wyndford, there are many options available for each house type.
Energy solutions really are a balance of possibilities.
Carbon reduction is king at the moment.
It’s also worth considering how the retrofit
actually affects residents’ weekly fuel bills.
Our initial survey work indicated that many
residents in the estate were paying excessively high fuel bills,
and the proposed introduction of a CHP
scheme not only reduces fuel consumption,
but also allows opportunities for
housing associations to have a flat-rate charge for fuel,
thereby helping to take a proportion of
residents out of fuel poverty.
However, although proposals for the high-rises
achieved significant energy savings in all cases,
the affordability to both housing association and
tenants is likely to be the decisive factor.
With the introduction of the Government’s feed-in tariff scheme,
the proposed biomass heat and power system would be eligible.
And there may be future benefits to
housing associations once the renewable heat incentive has been implemented,
as the heat output from the CHP would be
rewarded under the renewable heat incentive.
If we are to meet the government’s 80% targets,
and make radical improvements to energy performance,
we must be proposing solutions that
go beyond current building regulations.
If the options proposed in this study were installed,
and given the scale of the Wyndford Estate,
it has the potential to become a
flagship UK demonstration project.