Sunday, 11 November 2012

Annual Review

We've now been in the house for a year so this seems as good as time as any to give the house and its technology a check-up, so let's start outside the front door and work up to the roof.

The Insulation

The external insulation is a winner (mind you, I don't know how it might compare with cavity wall insulation).  Although this year the cold weather has arrived a month earlier we didn't need to put in additional heating until the outside temperature fell to about 8°C at the end of October. It's hard to judge how soon we would have put heating on in a 'normal' house but I should think this was a good month later and in the spring we turned the heating off in early March. It therefore looks like we only need heating for five months of the year (maybe!). 

The Porch
The porch is great on sunny days in spring and autumn as it traps the sun. You can then open the internal door and let the warmth into the entrance hall which reduces the amount of extra heating you need. In winter, especially on a grey day, it gets freezing and you have to be really quick coming through the door so the cold doesn't get into the hall. In summer you have to have all the windows and external door wide open in an (often unsuccessful) attempt to cool it down. Leave any plants in the porch between June and August and they fry but the rest of the time they flourish and I have spectacular cyclamen in winter. Basically, the porch is a very expensive greenhouse.

Maybe it's me but the word passive doesn't quite tally with our experience of the heating, cooling and ventilating of this house. In the summer we were forever trying to cool it down and now the weather is cold we have tried endless permutations to get the internal temperature comfortable.

Of all the aspects of the house that we've found vexing this is is the pièce de résistance!

In the summer we eventually evolved a convoluted system of  excluding the sunshine during the day, messing round with the MVHR and opening the windows on the top floor to draw heat up through the house but it was really only the dismal weather that made things tolerable. In summer the average internal temperature was about 23°C but it could reach 26° if we weren't careful.
Now the house is struggling maintaining 19° but to achieve this we've had to develop a system of turning the fans to their lowest setting when the heating system that comes with the MVHR is off and onto their middle setting when it's on. The electric heating uses the most phenomenal amount of energy so at the moment we have it on for five hours in the morning and in the evenings we have plug in radiators to warm the room we're in.

We're also having to remember that whilst in summer you keep all the doors and windows open, in winter you have to keep everything closed - except when the sun is shining because then you need to open all the doors and blinds to let the whole house warm up..... If you watch Dr Who you'll be aware of the running joke that the TARDIS has a mind of its own. We haven't had to resort to hitting the heating controls with a hammer but we've felt tempted on occasions.
So, on the space theme, here's Saturn again representing the vents that blast air, at various speeds, into the rooms from the fans. I know the physics of all this but I do wonder why they are placed where they are in the rooms. The only room where you really feel the benefit of the system is the room where the desk is directly opposite the vent so I'm not sure why we don't have under-floor heating of some kind instead but maybe that's my inner classicist coming out. In the same way, in the summer, it was only sitting at the desk that you could feel the benefit of cool air coming in from the fans.

The corridors don't have vents at all so in winter, unless you keep the doors open, the corridors get very cold and in summer, as I've mentioned before, there seems to be no way (apart from opening the windows) of cooling the top floor so, in general, I remain baffled by the MVHR system (even with an English version of the manual).

Hot Water
I promised you a picture of the new 'improved' hot water cylinder back in September and here it is.

Looking back I see the spec for the water cylinder that preceded this one; as far as we can tell changing the cylinder hasn't made any difference to its efficiency.

The only difference we've noticed is that the display now works.
This means that we can now quantify how much energy the solar tubes produce, as the generation meter only records the PV generation. By the power of mathematics this has allowed us to calculate that over the year we pretty much generate 100% of the energy we use, even taking into account the poor summer and chilly autumn.
Chuck a few sunny autumn and winter days into the mix and we will be generating more than 100% of our energy over a year. The graphs will appear in a later post. 

Rainwater Harvester 
Oh dear.

Well, it's been drained and cleaned and had its pump replaced but the only time we've used it is when the local water board turned off the water supply for a day.

It works for the loos on the ground floor and it works on the middle floor but, alas, whilst the pump can pump the water from the harvester up into the house it can't pump it up to the top floor so it's only 50% effective.

Also, since the pump was replaced, everytime you flush a loo there is a curious rumbling sound like a distant pneumatic drill. Not that that is so much of a problem in the winter because you're having to keep all the doors closed (see above).

Really easy to clean and great cooling effect in summer but equally cool in winter so you need to wear sheepskin slippers to keep warm.

Drop something on it and it shatters neatly - there is no bounce at all so I'm glad there are no toddlers in the house.
In order to be more eco we have reduced water flow and this is another thing that drives me mad. It means that it take four minutes (believe me, I've timed it I was so incredulous) for the shower to run warm water if you're having the first shower of the day and four minutes to start hot water coming out of the tap when you wash up. Ironically it means you run the taps longer than you would just so you can get hot water, go figure.
External Blinds & Triple Glazing
The blinds play a vital role in keeping the house cool but in a perfect world we would have them on the east window on the first floor and the long windows on the west as both let heat in in summer. We also badly need external blinds on all the roof windows - including the ones on the north side of the house, especially at the western end as in summer the sun is high enough in the sky to shine directly in. The triple glazing is brilliant and there's no noticeable loss of heat through it so whether you sit next to the window or on the other side of the room the temperature feels the same.

PV Panels

28 panels and they generate enough energy to run a home and an office, including all our heating. Plus the house is occupied 24/7 and we're not hair-shirted greens we do have DAB radios (6 Music is the only thing that keeps me sane!), TV, laptops etc.

Does someone want to explain to me why we don't have a Green New Deal to put solar panels on all public buildings?

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