Hello! I hope you liked the mini-documentary
on the Prêt-à-Loger house. During this lesson I will recapitulate
how the approach of smart bioclimatic design was used in the redesign of the terraced house. As you may have picked up, Prêt-à-Loger
was a submission of the TU Delft team to the Solar Decathlon competition
of 2014 in Versailles. The competition between 20 university teams
was held in a part of the gardens of Louis Quatorze, the sun king. Very appropriate! In contrast with other teams,
our students decided to come up with a plan to solve a much more urgent problem
than designing a new house: refurbishing an old one, which represents
1.4 million dwellings in the Netherlands, the typical terraced row house.

For the design process
we started with an analysis of the local climate. Here you see the temperature map of the Netherlands. On the right you see the differences
during the 12 months of the year. And this is the location of Honselersdijk,
where our house is situated. What can we learn from this? The annual mean temperature
is only 10 degrees Celsius. People typically want an indoor temperature
of around 21 degrees, so the climate actually
is too cold by 11 degrees. So most of the year, even with climate change,
it is important to capture the sun and preserve the heat by thermal insulation. It also means that the soil’s
will fluctuate only limitedly around 10 to 11 degrees, and that you can use the soil for pre-cooling
in summertime and for pre-heating in winter. Later we will see how that is done. Here we see the climate map
for precipitation in the Netherlands, with the location of our house
and again with monthly differences on the right.

Our house receives 850 millimetre of precipitation,
mostly rain. The house has a roof of 50 square metre. This means a total amount of
42.5 cubic metres of water will run off. This is equal to what is currently used
for the toilet and garden. A no-brainer, especially if you know
that we now use high-quality drinking water for these purposes. Looking at the wind map and pattern, we see that the coastal region
of the house has very strong winds. 6 metres per second on average, which is
21.6 kilometre per hour, or 13 miles per hour. This seems like a good business case
for wind turbines, which is true, but in this part of the country
there is a lot of horticulture, among which no big turbines are allowed. And smaller urban turbines are relatively
expensive for what they produce. Solar panels are more effective. So let’s have a look at the sun.

You already know this sun chart from a previous lesson. Good to know that the solar intensity
on a horizontal plane in this part of the world is around 114 watts per square metre, which is exactly
one thousand kilowatt-hour of solar energy. So the total amount of passive solar energy – for instance through one square metre of glass roof – is also one thousand kilowatt-hours. If we produced hot water through a solar collector,
the yield would be approximately 450 kilowatt-hours, and if we used photovoltaics
– PV – around 150 kilowatt-hour of electricity
would be generated in a year’s time. Now looking at the chart,
this is the orientation of the garden of our house. And this is the street side. This means that if we want
to do something with solar heat, we should use the garden side. OK, I think we know enough now
to start to look at the retrofit proposal. This is a section of the original house from 1960.

It has timber-framed floors and roof slabs,
next to a non-insulated cavity wall of sand-limestone on the inside
and masonry on the outside. The windows have single glazing. In the first step – reduce –
we added post-insulation to the house. Internal roof insulation and ground floor
insulation were the easiest parts. For a thickly insulated north-western façade,
we knocked out the outer gable wall, added twenty centimetres
of vapour-permeable insulation, and covered the exterior with brick slips,
as you have seen.

On the south-eastern façade, the cavity of
the wall was filled with vapour-permeable insulation. As another measure of step 1, we replaced the single glazing
by the best-insulating double-glazed windows. And we introduced daylight-catching solar tubes. Now, this was a more complicated step of our re-design. Here you see how fresh air is let in
through pipes in the underground, taking on the stable temperature of the soil,
before it enters the house. A heat exchanger establishes
a maximum heat recovery from exhaust air. Going even further, step three,
the generation of renewable energy, can be divided into electricity and heat, both linked to the most radical
intervention we did: the greenhouse. The structure of this greenhouse
contains solar cells in-between two glass panes, the power station of the house. But the greenhouse also captures solar heat,
which rises and forms the source of heat for an adiabatic collector between
the original roof and greenhouse, which extracts the heat,
hence cools down the air and solar cells, and transports it to a hot water tank, where a heat pump boosts
the temperature to 55 degrees Celsius. This hot water can be used
for the radiator heating and for showering.

The greenhouse and roof
are also used for rain water collection, which is stored in a tank under the extension. This water is used for toilet flushing
and watering the plants. And talking about the plants:
the student team also wanted to demonstrate how a dwelling like this
could contribute to biodiversity in the neighbourhood. They did so by adding green roof to the north-west, introducing plant species suited for
the local climate in the front and back garden, and by proposing the growth of herbs, fruit
and vegetables, also in the greenhouse. So this is what the Prêt-à-Loger house
looked like during the competition in Versailles. As you can see,
we mocked slicing through the neighbours, allowing visitors to see
the differences between the original section and the retrofitted dwelling in the middle.

It won several prizes and can be called
the most sustainable terraced house in the world. You may have seen that the house
was rebuilt on the TU Delft campus and now still serves as demonstration object,
as a living lab. I hope this film clarified the decisions taken
for the particular terraced house, which turned it into the Home with a Skin. See you next time!.

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