Withington Co-operative Eco-house - rainwater harvesting

A day of dealing with various things

Robert — Wed, 19 Jun 2013 20:53:00 +0000

Set up a basic site office in one of the bedrooms - desk, chair, whiteboard, drawings on wall.

Had another meeting with the sprinkler company - pipe runs etc pretty much all worked out, and agreement for first fix to start a week on Monday (1 July).

It's awkward to get sprinkler coverage in rooms with sloping ceilings (as we have on our top floor), and as sprinkler coverage isn't required in rooms less than 5m2, I came up with the idea of making the top floor bathroom slightly smaller, to get it under this size threshold (it seems pointless to have sprinkler coverage in a bathroom, but at the end of the day we need to say we have complied with BS9521). This would necessitate omitting the bath from the design, which I didn't see too much of a problem with - and that top floor bathroom was crowded anyway.

The rainwater harvesting system arrived (everything but the underground tank, which is being held back until we get rear garden vehicle access). I specifically wanted the header tank on-site to ensure that the joiner builds the cupboard that will be housing it to the right size. And it was a good job I did, because I found out that, including its lid, it is just a little bit too high to fit in the space between the top of the doorways and the underside of the existing ceiling - so the ceiling will have to be raised in this area. I also hadn't realised that it has a 40mm overflow.

On similar lines, I ordered two of the single-room MVHR units (Manrose HR100RS), which should be delivered tomorrow.

I called Velux technical support to try to understand their somehow rather incomprehensible code numbers; good job that I did, as the guy helpfully pointed out that a smoke vent window is required to have at least 1m2 of opening area, and none of the Velux range with a width that would fit within the existing top floor stairwell would match. His suggestion was to have two smaller windows in-line; the other option would be to adjust the stairwell enclosure (which fortunately is all timber studwork). Need to investigate this and come to a decision ASAP.

This evening I had the future occupants of the house come round and discussed various things with them - all went well, apart from the omitting the bath idea, which they didn't like. We discussed various options including having a bath in the ensuite bathroom, and having an over-bath shower in one of the bathrooms (which I really don't like, as in my experience they always leak sooner or later - structural timbers soaking up water in an eco-house would of course not be good at all!).

Obviously it's not good to be firming up and making adjustments to the design at this stage - hindsight is a wonderful thing!

eBay bargain

Robert — Mon, 17 Jun 2013 14:36:52 +0000

Had a lovely weekend at Old Hall - communal living batteries now fully recharged :-)

I made sure I was back to be able to meet the builders on-site first thing this morning... but they called at 9am and said they weren't coming until tomorrow.

On the upside, I just bought this sink on eBay for the bargain price of £50!

eBay bargain - deep-bowl commercial sink for laundry

It's useful to have a deep-bowl sink so you can put a bucket under the taps and for non-food purposes; so we will be installing this in the basement laundry room.

I've also now placed the order with rainwaterharvesting.co.uk and everything apart from the tank itself should be delivered tomorrow (it will be useful to have the header tank etc on-site so that the builders can see what they will be working with).

Sprinkler company is coming on-site again first thing in the morning too, so looks like tomorrow's going to be a busy day!

Rainwater harvesting, and neighbours

Robert — Thu, 13 Jun 2013 17:49:57 +0000

The rainwater harvesting system we're going to use is from rainwaterharvesting.co.uk - they sell a complete system, in kit form. Because the tank is shared with the fire sprinkler system, I thought it would be a good idea to get it on-site ASAP, if possible. So I've been thinking about how to achieve this, given the road closure going on with the United Utilities works (The tank we'll be using measures 2.4m x 2.4m x 1m approx).

At the moment, UU have the side road (which gives us access to the rear garden) closed during the daytime, but then they open it to (small) vehicles before they finish work each evening. This is going to change in two weeks' time. So I came up with a slightly convoluted but workable plan: hire a 3.5t flatbed from Salford Van Hire, drive down to Peterborough, get the rainwaterharvesting.co.uk people to load the tank onto the vehicle, drive back to Manchester (by which time it would be after 5:30pm so UU would have finished work), and have a bunch of people ready to offload it into the garden (then return the van next morning). After making quite a few phone calls to confirm availability of both the tank and the vehicle, costings, ordering procedures, etc, I came to the conclusion that whilst I could get it in to the garden, this would be pointless unless we could get all the displaced earth out of the garden - and that we didn't have enough time to also achieve that, before the 24/7 road closure comes into force.

So we'll have to stick to Plan A: wait until the roadworks are finished before putting the tank in. I need to tell the sprinkler people about this; they sent through a CAD file following Wednesday's meeting, mostly OK but a couple of points to raise with them, which I'll have to do on Monday now.

I'm very eager to ensure that we have good communication, and good relationships with the neighbours. Both the adjoining houses are rented. I already know the owner of one of them, but yesterday I managed to speak to the other one on the phone for the first time. He seemed rather concerned, so there will be more work to be done to put his mind at rest. In particular, there are some Leylandii trees in the garden that we are going to get rid of, and what gets done about the boundary (ie do we build a wall, plant a hedge, etc) will need some careful negotiation. He promised to have a word with his tenants, and then we'd speak again next week.

Fortunately for this project, my time is not being charged for - but in other circumstances such time would have to be paid for, yet the above aren't things you can "see" in the finished result. I had no idea when I started that my time would be needed for these kinds of things - certainly something to bear in mind for future projects.

Going to see the window supplier on Monday morning, which I'm quite excited about.

Design approach: rainwater harvesting

Robert — Fri, 07 Jun 2013 18:00:00 +0000

Rainwater harvesting seems like an obvious thing to do to me - capturing the rain that is inevitably going to fall on top of our buildings seems like a even more of a no-brainer than capturing the sunshine that reaches our roofs. Ironically enough, the logistical difficulties we're having on this project due to road closure are because United Utilities are having to put in an enlarged sewer due to the original Victorian drain being unable to cope with today's increased water usage (as well as its poor state of repair); if every house on the street harvested its rainwater instead of dumping it down the drains, that would yield a reduction in wastewater volume of at least a third.

Rainwater harvesting systems are difficult to retrofit in anything other than a whole-house refurb, because you have to have a large underground tank (rainfall has seasonal variation of course, so you need to store a large volume to benefit from the system) and two sets of pipes running around the house, to keep drinking water and rainwater supplies separate. But if you are starting from scratch with your plumbing, rainwater harvesting seems to be a no-brainer.

There has been some criticism of the significant embodied energy in the rainwater tanks not being fully taken into account in assessing the environmental benefit of rainwater harvesing systems, compared to energy saving from reduced drinking water consumption. On this project, we're very aware that there is also significant embodied energy in the drainage systems that take rainwater away from buildings, if it isn't harvested. And for this particular project, because we've chosen to install a fire sprinkler system, we are going to use one shared tank for both the sprinklers and WC flushing. So it could be argued that, as the tank is required anyway for fire safety reasons, only the additional plastic in the increased sidewall area to accommodate the extra water for WC flushing would be included in a rainwater harvesting embodied energy calculation (by the way, we're not doing any quantitive embodied energy analysis in this project - not because it's not important, but due to lack of capacity).

The difficulty, for a mid-terraced house such as this, is that it's only really practical to capture rainwater from one half of the roof (the rear, presumably); a two-tank system and running large diameter pipes through the house were both quickly ruled out as not viable. For this reason, we're only using the rainwater for WC flushes - the calculations we've done are that it won't necessarily provide 100% of WC flush water, so it wuold be pointless to start plumbing in other things eg washing machine.

The chosen system is available "off the shelf" from rainwaterharvesting.co.uk, who supply the whole system in kit form. The things I like about their offering, compared to others I've seen are:

1. There is a header tank in the attic, rather than supplying appliances directly from the underground tank. This means that the supply is more reliable, and the electricity usage from the pump (already very low, we're promised) is significantly reduced, because pumps work more efficiently if run continously rather than stop-start.

2. The Rain Director control unit deals with switching over to mains water in the event that there's no rainwater left, and can cycle the water to stop it going stale if, for example, people are away on holiday.

3. The tank is shallow-depth, only requires a hole 1m deep.

I spoke to the supplier at Ecobuild, and again more recently on the phone. They are going to supply an adaptor to allow us to fit an upstsand pipe to the inlet of the submerged pump, so that the inlet will be physically part-way up the tank, thus guaranteeing that the WC flushes can't "steal" the water that is reserved for the fire sprinkler system (the sprinkler system will use a separate suction lift pump).

Withington Co-operative Eco-house - rainwater harvesting

A day of dealing with various things

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eBay bargain

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Rainwater harvesting, and neighbours

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Design approach: rainwater harvesting

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