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Hello, my name is Rosalie Menon and I’m a member of
MEARU - Mackintosh Environmental Architecture Research Unit.
Today I’m going to talk about an energy feasibility project
for Cube Housing Association in Glasgow.
Following on from Colin Porteous’s
presentation of the Easthall Retrofit project,
I’m going to talk about a more recent housing
feasibility study which MEARU undertook for
Cube Housing Association for the Wyndford housing estate in Glasgow.
The context for upgrading Glasgow’s social housing stock
has shifted substantially since the early and
mid 1990s when Easthall was conceived.
15 years on, we have embraced an era of governmental energy targets.
There’s now a wide governmental and scientific
consensus on the need to shift to a low-carbon economy.
The Climate Change Act 2008 required that
by 2050 the UK’s annual carbon dioxide emissions
should be reduced by 80% compared to 1990 levels.
Home energy use is responsible for over a quarter of UK CO2 emissions,
which contribute to climate change.
We must therefore aim to reduce CO2 emissions from
all dwellings by an average of 80% to help meet
the UK’s long-term goal.
At current rates of demolition and new-build it
will take almost 1000 years to completely renew the UK housing stock.
So, most of the homes still standing today will
still be in use in 2050.
The challenge is to refurbish the homes of the
past as homes for the future.
How do homeowners, tenants and housing associations
decide what needs to be done and how it should be achieved?
What are the costs,
the paybacks and the technical constraints?
So, it’s a big challenge for housing associations,
and given the wide variety and building types in
Scotland’s social housing stock,
there is certainly no “one size fits all” approach to existing homes,
and as I outline in this particular project,
energy solutions are a balance of possibilities.
In their initial brief to us,
Cube made it clear that solutions must be
economically pragmatic and capable of phased implementation.
For example, their initial cost analysis had
ruled out over-cladding all the high-rises.
However, a minimum requirement was that all
housing was to be brought up to the Scottish Housing Quality Standard.
This means achieving a minimum SAP rating of 60,
or 50 with a full central heating system and appropriate insulation.
Cube Housing Association also expressed interest in a
CHP system as a solution to this option was also explored in detail.
MEARU was approached by Cube to undertake an energy
feasibility study on the upgrade of their
existing housing stock in the Wyndford Estate in Maryhill.
The estate has a variety of building typologies,
from 4-storey maisonettes to a 26-storey tower block.
The estate was constructed in the 1960s
and earned a Saltire award in 1968.
Whilst our study included both high-rise and maisonette typologies,
I’m going to discuss three different high-rise
scenarios in this presentation.
Exploring practical and economic means of upgrading the scheme
thermally was paramount to our brief and to meeting
particular minimum standards included in the
Scottish Housing Quality Standard and the
Energy Savings Trust best practice refurbishment guide.
Where practical, our proposals also moved towards the
German PassivHaus compliance.
A sample of each of the house types was surveyed in 2 stages.
Initially, a building fabric study was undertaken from a
selection of void properties which could be accessed
for the purposes of a visual inspection.
Original construction drawings were sourced from
Building Control archives,
which provided an understanding of existing wall
and roof construction sections,
and allowed U values and as existing SAP ratings to be calculated.
The residents’ surveys were also undertaken in two phases.
Initially there was a postal questionnaire sent out to all
residents within the estate which yielded a high response rate,
a total of 402 residents responded.
The questionnaire asked residents how they heated their homes,
their familiarity with heating controls,
and how much they spent on fuel bills.
Predictably this yielded many complaints of
inadequate or otherwise unsatisfactory heating.
Apart from the lack of heat emitters,
poor control coupled with charge times were key issues,
with many residents resorting to the use of
additional heating appliances such as
oil-filled radiators on the higher direct tariff.
For example, a quarter of the respondents had
additional appliances in the living room,
and almost a fifth in the bedroom.
There were also many complaints of discomfort due to cold drafts,
some of these probably due to cold surface temperatures
rather than infiltration of cold air from outside.
Winter electricity bills were also predictably high.
A quarter of the sample reported spending
between £20 and £30 per week on electricity.
Following the postal survey,
a face-to-face survey was undertaken with a
selection of 20 residents in their homes.
Spot measurements of temperature,
CO2 and humidity were recorded to assess air quality.
During the face-to-face interview,
residents were also questioned as to their heating
habits and patterns of usage,
together with their preferred methods of heating.
Casual observations were made by the surveyor,
many being that additional heaters were evident,
proving that residents were finding existing
storage heaters ineffective.
Likewise, drying clothes on supplementary heaters
confirmed residents’ high energy consuming habits.
Based on all the survey information gathered,
proposals for energy efficient upgrades were proposed by MEARU.
Each option or combination of solutions were tested using SAP,
NHER rating system and BREEAM methodology.
Proposals for each housing type were reviewed and
discussed with Cube Housing Association and their
QS regarding economic feasibility and proposed phasing structure.
Today I shall discuss three house types forming part of the study,
all high-rise, each of which I will discuss the
existing conditions and proposed energy upgrade scenarios.
Similar to the other tower blocks in the estate,
house type 1 was built in the 1960s as a concrete panel system.
This is the highest in the estate at 26-storeys,
and there are four such examples of these in the estate.
As external cladding was not an option to be pursued by Cube,
MEARU proposed these towers to be internally insulated,
with balconies glazed as buffer spaces.
No new glazing was proposed as the existing
UPVC double glazed units had recently been replaced.
It was proposed that the existing roof
could be converted to an upside-down warm deck or sedum roof,
in order to reduce the U value to 0.2.
These upgrades would reduce the thermal load for space heating,
together with domestic hot water to the point
that it’s likely to provide reasonable load matching
relative to a CHP system.
This means replacing the 2 electric storage heaters
in each flat with a wet heating system.
On the basis that hot water can be distributed
vertically in the ducts lining the bathrooms,
horizontal and vertical pathways for radiators appear relatively simple.
The provision for CHP will inevitably be a major commitment,
but it’s reflected powerfully in the predicted SAP and NHER ratings.
The new SAP value would be 76, up from 35.
With the proposed upgrades and CHP system,
a typical apartment flat estimated
space heating load would be 3300 kilowatt hours,
58% less than existing.
House type 2 is the 15-storey towers,
again built in the 1960s and concrete-frame construction.
MEARU proposed towers to be cavity-insulated and windows
replaced to 2007 norm of 1.8 U value.
Similar to the 26-storey block,
converting the existing roof to an upside-down warm deck,
it should be possible to reduce the U value significantly.
These upgrades will reduce the thermal load for
space-heating together with domestic hot water,
again to the point that it’d be reasonable to provide a
load match relative to the CHP system.
The estimated space-heating load of a
3-apartment flat is 2005 kilowatt hours,
69% less than existing.
The predicted energy values correspond to the
SAP rating of 76, up from 42.
It is worth noting that the communal laundry in these blocks
are also a well-used facility and should
be retained to reduce moisture loads in flats.