Given my energy background, it was natural that I would set about
improving the energy performance of my house when I moved in over 18 years ago.
It is a detached bungalow built just before the first oil crisis of 1973 with
little or no consideration for energy issues. It can be seen from the graph
below that the reductions in energy use I have achieved (about 75% in the last
14 years) have come in several phases.
Following the large reduction in gas usage in 2007, and the
subsequent installation of solar systems in 2008 and 2011, I have begun to
focus more on my carbon footprint rather than just energy reduction. Now that
my carbon emissions are barely 300 kg/year (most houses are measured in
tonnes), I think it is reasonable to refer to my low carbon house and since
I've passed the 90% renewables contribution landmark I've even allowed myself
to start thinking of the Holy Grail of Zero Carbon! The graph below shows
the contribution of the different renewables over the past 12 years.
Prior to 2009 I had reduced the heat losses through roof, walls,
doors and windows substantially over a period of years. The large
reduction in gas usage in 2007 came from a combination of disconnecting
the underfloor heating in my conservatory (and sacrificing some tender plants)
and pumping foam insulation into the 9" hollow block walls. The
reduction in gas usage in recent years is due to the fact that I have been
decommissioning my central heating system room by room as I have worked my way
through the house putting in underfloor insulation and sealing off each floor
with Intello airtight membrane (http://www.ecologicalbuildingsystems.com/).
Only the sitting room now remains for this treatment in 2013. Each of
these rooms now has a Süka wall-mounted electric heater which is
thermostatically controlled and I have each one on a timer suited to the
usage pattern for that room.
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Installation of underfloor cellulose insulation
and Intello membrane
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In March 2011, I had an air tightness test conducted by Christ
Spoorenberg of EcoScan. The results
were a slightly disappointing 7.68 Air Changes/Hour @ 50 Pa and a Permeability
of 6.17 m3/h.m2. However, as I was less than halfway through the sealing
process outlined above at that time, it may not have been too bad and, in
addition, the thermal imaging also carried out showed up a number of weak
points where I was losing heat such as hall door, hot press, fireplace/stove
and attic door. I have subsequently dealt with all of these now apart from the
attic door.
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Extract fan in back door
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Cold air (blue) around attic door
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The reduction in electricity use has been achieved by means of a
detailed audit of all appliances, and their usage, and systematically
going about tackling each of them. Whenever I'm replacing an appliance I choose
the most energy efficient option available - the most recent example of this
being an amazing induction hob in my revamped kitchen. LED technology has
advanced rapidly in recent years and I now have an LED option in almost every
room which has more than halved my electricity usage for lighting in recent
years. A dramatic reduction came in 2008 when I installed SOLARFOCUS solar panels for hot water and in
the process did away with both summer electric immersion and electric
power shower in one fell swoop - anyone used to a power shower might find
my gravity fed shower a little tame but I find it more than adequate!
It may seem counter intuitive to be putting in electric heaters but
the heat loss for the house is now so low (less than 3kW) that they
are only needed to supplement the solid fuel stove I installed in
2006. In addition, I am now generating my own electricity from my
solar photovoltaic (PV) system (see my separate post on this for more detail
and latest data) and, as I am exporting almost 80% of
output to the grid, my net purchase of electricity is running at just
over 500 units in a 12-month period at a net cost of about €200. It seems to me very last century to pipe a fossil
fuel halfway across Europe into my home to burn it in a boiler and
then pump the hot water all around my house!
In December 2013, I replaced the existing solid fuel stove with a
dedicated Charnwood C4 wood burning stove. I choose it for its clean-burn and air-wash
technology designed specifically to re-ignite volatile by-products emitted by
the initial burning. As wood is composed of 80% volatiles this is critical and
I am amazed at how little ash is being produced which indicates to me that I am
getting a very complete combustion. This series of stoves also features an
integrated inlet for ducting external air to the combustion area rather than
sucking it from the room and combined with the flue liner connected to it
(rather than going straight into the chimney as with the old stove) I now have
a closed airtight system. Pat
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Ready for Winter!
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