future simple passive

31 Jul 2014

The Airtightness Test

We set out to achieve a low energy house with the principles of "super-insulate, build tight and ventilate right". This means that the building needs to be pretty airtight. This ensures that the air that you heat can't just escape through gaps in the building, it is directed through the MVHR to heat/cool the incoming air - minimising additional energy input. The other thing to worry about when air leaks is that the internal air will be warm and moist, when this moves through a gap in the fabric it can cause interstitial condensation - damp and mold! No good!

To conduct the test the building is sealed and a calibrated fan is mounted in a doorway. It sucks air out of the building to depressurise it. Then they can test the pressure differences between outside and inside and watch what happens as they test at different pressures. A number of different data points are collected and graphed, creating a final averaged figure. We have tested twice now and will have one final test when the building is finished. So the first two tests have been used as aides to discover where in the building the airtightness needs to be improved. As the inside is depressurised it pulls in air from outside (actually air from outside pushes in and tries to fill the space) and you feel with the back of your hand where air is moving through the building envelope.

Searching for leaks

Two figures are calculated in the test; air permeability and air changes per hour. The two figures are very similar and to be honest i'm yet to really understand the difference! (Dimitri says "One is flux and the other is just a measurement that builders and architects can understand"!) However it is the Air Changes per hour that we are really interested in. Air permeability is measured in cubic metes per hour per square metre of the dwelling envelope area when the building is subjected to a differential pressure of 50 Pascals (m3/(h.m2)@50Pa). Air changes per hour is the number of times all of the air in the house is replaced in an hour at the same pressure difference as above(without MVHR obviously).

Building Regulations state a maximum figure of 10 air changes per hour, although 3 is the minimum standard for AECB (Association Environmentally Conscious Buildings) Silver Standard for environmental building. Passive Houses have to achieve 0.6. Getting a score of 10 down to 5 is relatively easy, however from 1 to 0.6 is very challenging...

The first airtightness test was conducted once the windows and roof had been installed. Where the concrete blockwork meets windows and doors and the roof, we have used a lot of very expensive airtightness tapes. We've been told these tapes will last for 50yrs, but to be honest no one has had them in use for that long so nobody really knows as lab conditions are never quite the same thing as reality.

Paul Jennings, the airtightness guru, arrived with all his gear and got to work. We achieved a result of 4 in the first test, we were all disappointed! Leaks were searched for around junctions of the walls and windows and roof and sealed with more tape. This got the figure down to 3.6. Not the start we were hoping for.

Unusually for a passive-style house, we have used traditional concrete blockwork. Blockwork can vary a lot in air permeability and the more environmentally friendly blocks composed of fuel ash can make the blocks even more porous and very leaky. So the blockwork could not be relied upon to give us the airtightness. The redeeming feature of blockwork is that it is a great thermal store, absorbing heat and very slowly releasing it. It will take a lot of energy to change the temperature of the mass. At this point in construction we had used blackjack, a paintable bitumen, as a seal when perforating the blocks, so we guess that this had not been as effective as we had hoped either.

Once our internal render had been completed we conducted our 2nd test. This time the first score was 0.9 - hooray! We were under 1, which was the figure we were aiming for when we first began this journey. A huge accomplishment. We always said that the aim was to do the best we could without throwing huge amounts of money at it. The costs can increase exponentially as you get down to the final 0.1s. Just goes to show what a difference a layer of render can do.

But Andrew and Charlie were really hoping they could make it to 0.6. It's boys- they see a target and they want to hit it, goal driven! With more rushing around with smoke pens and backs of hands against junctions they found some more air movement and used an airtightness sealant and mastic to fill the voids. Apparently this stuff is the business and doesn't fully harden and leak at a later date. A lot of our issues were around the electrical switch boxes and the wire perforations through the render.

There was a lot of nervous tension as we waited for the final series of tests to be performed.

We managed to get a result of 0.72! I think that is amazingly good! The photo below shows a result if 0.62, however each result has to be plotted on a graph and it is the average which determines the final score.

I am so delighted. 0.6 would be great but to be honest the difference of 0.12 is nothing that we will notice, our house is going to be super low energy and that is what we wanted. It remains to be seen whether we'll improve the score by the 3rd test. Andrew is planning to use some of the mastic inside the switch boxes in an attempt to improve the score. We've also completed the plaster layer now which may have an impact. However it has been known for scores to increase in the final test, as during the final finish more perforations are made in the airtight skin when you hang shelves and so on.

(I have to confess that I failed to write down the scores at the time, believing that they would be indelibly etched into my memory, however that has turned out not to be so! Paul may correct me if I've got any of these numbers wrong.)

10 Jul 2014

Render and Plaster

Those experienced in the building trade know the difference between render and plaster.

The render, sand based cement with waterproofing additives, went off really quickly. We think it must be the thermal mass releasing the heat from the last couple of weeks of good weather. It's this layer of render together with the plaster which forms the majority of our airtightness layer. The plastering was started a couple of days earlier than expected.

In order to keep things simple visually we have chosen a shadow gap detail on the door. The stop bead itself is not expensive, but it was the fact that they only sell them in boxes of 50 which put the costs up. So we now have about 30 pieces unused in each box, as we needed two different sizes of bead - anyone interested in buying them? I'm becoming a supplier now!

There was a break in the work after all exterior walls had been rendered but not yet plastered, when we performed the critical air-tightness test (next post).

WOW! Mike and his team, R. Churchill Plastering, have done a fantastic job. A local firm who were able to fit us in on pretty short notice. It's a beautiful trade to watch - it's like ballet! It's really looking like a proper house now.

6 Jul 2014

1st Fix Completion & MVHR

Alongside the 1st fix of plumbing and electrics, there was plenty of 1st fix carpentry to get done. All openings and junctions got taped up with the very, very pricey airtightness tape.

Andrew and Paul also cracked on with the MVHR (Mechanical Ventilation with Heat Recovery) installation. We are using an Airflow system. Large red oval ducts are running through the ceiling.

As the house will hopefully be incredibly airtight, we need a mechanical system to circulate air. The MVHR will take out stale air and condensation (from the kitchen, bathrooms and utility areas) and bring in fresh air (to the bedrooms, sitting room etc). It will use the heat of the extracted air, via a heat exchanger, to warm the supply air. Equally if the air inside the house is cooler than outside then it will cool the incoming air. The efficiency is more than 90%, so will we have to use very little energy to maintain internal temperatures. I'm really looking forward to the air quality - we will have fresh air constantly flowing into the house. Everyone who has installed it is evangelical about it, the comfort levels are supposed to be fantastic and they say they notice the difference when they go into normal houses, especially in the winter when people keep the windows closed. Allergens such as mould, dust and pollen should be hugely reduced too.

The sliding door running tracks were fitted.

Preparing the steels for render and plaster.

Andrew and Paul worked flat out in order to get the place ready for the plasterers to get started while they had a short break in the schedule (Paul was off to enjoy Glastonbury).

Starting to look like real rooms now!

4 Jul 2014

Lighting Re-re-design...

The lighting design has been a lot of fun and games. Mat, my electrician (Aspey Electrical), has shown a lot of patience and support as I have had to very quickly change almost everything related to the lighting design. We definitely wanted to use LED lights (low energy house!) and we wanted to keep costs down so I had asked for loads of LED strip lights to be concealed behind wooden plank pelmets which would wash the walls with light. I wanted to avoid spot/down lights as much as possible. However once we got to site everyone in the business was quick to tell me that LED strips just wouldn't provide enough light! Very quickly I had to change the designs and specify exactly what would replace it and where it would be located.

Lighting is a nightmare as there is so much choice out there. It is very technical and definitely user unfriendly. Unlike bathrooms there aren't really any showrooms you can go to, to get your eye in and see what the choices are. I browse the internet and find a fitting I like, but then there will be 4 different versions and I don't really understand what the differences are, and I still am none the wiser as to whether it will be suitable. Also, lighting is where, if you are looking for non-standard items, the budget can be blown - it's silly money mostly. The difficulty is finding what there is out there. At the moment I'm just browsing the internet, finding what I like and want to do and then passing it over for technical support.

In the living area I'm having a pendant light over the kitchen island. I love this light, Plank, and think something inspired by this would look amazing in our birch ply kitchen. As it is £600 it's just not within our budget.

Plank, Northern Lighting

Over the dining table there are a triplet of pendants. The exact light fitting hasn't been chosen yet. I've been quite taken with some reclaimed glass funnels from Retrouvius. I like the way they are small and elegant with a bit of extra quirkyness and, for £65, affordable.

Small glass funnel light, Retrouvius.com

1st fix begins!

Site is a crazy place at the moment with a huge amount of people and activity as our plumbers, Cotswold Green Energy,

and electricians, Aspey Electrical, commence 1st fix.

For novices, like me, this is all the wires and pipes that are hidden behind the plaster walls- the skeleton of the building. And there is a lot of work to be done!

There is lots of pressure on everyone as we have to get this all correct. As it will be behind plaster we can't change things later (you can of course but at a huge amount of expense and time).

Do you remember those lovely service plans that I did with Charlie a month or two ago? I thought that it had all been taken care of. It turns out those were just the starting points. As a result I've spent a lot of time on site for the last couple of weeks.

Plumbing has been relatively straightforward as I had spent hours on detailing the bathrooms (see here), so I had all the specifications and details at hand. I'd also made design choices which made the plumbing in these areas simpler e.g. a ply wall and shelf will conceal the pipework and cistern, rather than chasing them into the blockwork. Charlie from Cotswold Green Energy has designed our heating system so I didn't need to get very involved in that side of things.

On the electrical front, plugs and switches have been relatively straightforward. There was only one plug position that had to be changed, Mat was extremely thorough and so everything else was really well positioned. Lighting however has been a bit of a horror (see Lighting Re-re-design). I was not prepared!

Making all these decisions and spending a lot of time in the house has meant that I am actively imagining living in spaces as they start to take shape. Experiencing the spaces is so different from seeing them on plan. Ideas inevitably change, but things also clarify and the simple solution is obvious. This is what house-builders are strictly advised not to do, change things, due to the resultant uplift in costs but as we are not on a fixed price contract I do have more flexibility. I'm just doing what everyone who has built before has advised me - "trust your instincts", and it's OK. We're getting there!

26 Jun 2014

Bathroom love...

I can't tell you how many hours I have put into these bathroom choices. I don't know why bathrooms are so important to me. I have visited countless show rooms, and browsed untold numbers of catalogues. With my now extensive knowledge, I even helped a friend realise she had a quick release toilet seat which she didn't even know existed!

So, drumroll...the final selections-

I initially specified Grohe taps and shower valves- I like reliability and that is worth spending on (you will pay the extra cost many times over just to get the plumber out!). But I was advised by my design team and plumber to take a look at Crosswater as an alternative high quality brand with a good record for reliability. Their prices are extremely competitive, the design is really lovely, and their products come with a 15yr guarantee. The choice was made.

Bathroom basin taps will be the Crosswater Svelte basin mixer. Lovely simple lines and felt great to touch- nice weight and action.

The shower valves are from Crosswater Central Collection. Again really clean and simple lines. I love the landscape orientated bath/shower valve that we will have in the family bathroom. In the ensuite we will have the portrait-orientated Central shower valve. All the shower risers, shower heads & wall outlets will also be Crosswater. As are the basin traps and click-clack wastes (so many decisions I didn't even know I had to make!).

As previously discussed I am very opinionated on ALL bathroom things, so this was an extensive and exhaustive search. The Euro range by Bathstore offered excellent design at affordable prices (especially in the Sale), believe me to get similar you will pay twice as much.

The basins will be from the Euro Duo range. Simple, clean & straight lines, I think they are very elegant and practical looking classic modern design. We've got a large 700mm one in the family bathroom, the 500mm in the ensuite, and a great narrow cloakroom version in the upstairs loo.

The toilets will be the Euro Mono Back-to-the-wall. Again simple lines, and has the all-important quick-release toilet seat. This is also straightforward to replace if necessary (for earlier ranting see here).

The only thing that would take the toilet to a heavenly ideal of perfection would be if I could have a chunky wooden toilet seat (I tried so hard to find a modern styled toilet where I could choose a solid wooden seat, they don't exist!). Maybe a groundswell of consumer demand will mean that the Bathstore design team will consider bringing one to market...wouldn't everyone prefer to sit on a warm chunky piece of wood rather than plastic?!

The shower screens took forever to decide. I mostly don't want to know they are there at all. They should be easy to clean. They've also got to be robust enough to stand-up to the ravages of family life. In the family bath we've chosen Simpsons Ten Hinged bath screen. It's as minimal as you can find and made using 10mm glass, which has a really luxurious feel to it. We can also fold back the screen during bath time, for easy access to slippery children!

The en-suite screen took a lot of deliberation. We had originally just wanted a single glass screen and really liked the Simpsons Ten Shower Panel, again minimal, elegant and loved the 10mm glass. But our shower tray is 1400mm long, so we had to think long and hard about the length of the panel, potential for water to leak out, and width of opening for access. We drew out the different options on the floor and Dimitri even brushed off his physics to calculate angles and potential for 'splash'.

In the end we went for a practical but elegant solution, the Simpsons Elite Walk-in Easy Access (not the most glamorous name!). The hinged panel at the end will give generous access, but will stop water leaking out as it can extend much further when flat. Practicality has to come first!

Towel rails are not necessary, we have underfloor heating in the bathrooms and the MVHR should mean that towels dry quickly, but who doesn't enjoy a warm towel in the winter? After an initial dalliance with a custom-made copper pipe towel rail, I did a 180º and found an grey anthracite coated rail, Edge by Bauhaus.

I finally decided on the bath (see here for earlier frustrations). Luckily I found a fantastic bathroom showroom really close by in Thornbury, Bathrooms 365, and they had both baths I had shortlisted on display. I've gone with the Kaldowei Puro, simple and spacious with the side overflow I wanted. Bathrooms 365 were brilliant, very helpful and with extremely competitive pricing so they will be supplying all the Crosswater/Simpsons/Bauhaus items, the concealed Geberit cisterns, and the Kaldowei bath.

I'll let you in on a secret. In the first throws of design I had desperately wanted to avoid chrome fittings. I wanted brushed stainless steel or copper even, something less shiny. However in a massive reality check I learned that unless you have buckets of money this is not a realistic option. Chrome is firmly here to stay. I'm come to a Zen place of acceptance now, after initial rejection and protests. I'm sure there must be a million reasons why chrome is the finish of choice, but for the record not all of us like shiny, shiny, shiny.

I can sit back and relax now (ha ha!) as a million choices have been made and I can say that I am excited about every single thing that is being put into my small but perfectly formed bathrooms! Obsessive, me?

22 Jun 2014

Appliances

The kitchen design was coming along as so attention turned to appliances...

Washing machine & dishwasher shopping is a nightmare! Finding the balance between cost/energy efficiency/long term sustainability has meant that I have tied myself up in knots!

For example, do you buy Miele- machines that will hopefully last for 15-20yrs? They have a higher initial cost but should be cheaper in the long run as the machine doesn't need to be replaced. It's better for the environment as there is less landfill. But will a machine still be efficient in 20yrs? Technology seems to be changing and improving so could there be an environmental payoff with upgrading after 5 or 8yrs? But how much more efficient can these machines get? Does the production cost of a huge hunk of metal outweigh relatively minor improvements of energy consumption costs?

AAARRRGGGHHH! To make things more confusing the energy rating stickers are not helpful...

Since most things have to be A-rated now, they differentiate between themselves with a A+, A++, A+++, A++++. So stupid. Each + means a 10% greater efficiency so a A++++ machine uses 40% less energy than a A-rated appliance (I think!). But you still have to look at the detail of energy consumption in order to compare machines in the same group. Some brands will give you an estimated annual consumption figure and some tell you the per wash figure. It is NOT easy! Also, these figures are based on a 60ºC wash, not the 30º/40º wash most people use everyday.

You also need to look at the water consumption figures of the washing machines and dishwashers. Is lower water consumption worth more in the balance against lower energy consumption? It seems so.

And THEN, you need to know that it is good at what it does. The WHICH consumer report has found that

"Unfortunately, extreme energy efficiency is not always a good thing for you as a consumer: some of the washing machines we've tested that use the smallest amount of electricity and water also produce the worst results. A washing machine needs to balance good cleaning with relatively low energy and water use. "

Which.co.uk

And, for the dishwasher, I want a low decibel rating as we have an open plan living area. I just want to run away screaming...! We haven't been able to make any choices yet.

Ovens, induction hobs, extractor fans, were all relatively painless in so far as there isn't much variation in energy efficiency across brands. So the choices were based on cost, functionality & aesthetics.

As we have an airtight home we can't duct out the extractor fan, so we need a recirculating one. These use carbon filters to remove the particles and smell, but there were rumours that this would compromise the efficiency of the fan. I didn't want to waste money on a powerful fan if it wasn't going to work properly. So, as usual, I talked to my favourite people- the engineers. I wanted an Elica fan, this is their sole business so I reckon they know what they are doing. I gave the technical department a call, and they were brilliant! Elica recirculating fans work to pretty much the same efficiency as the ducting fans. As my fan is to be hidden within cabinetry we identified the fan which gives the most bang for a buck and that is the Elicbloc HT 80. Easy.

We are going to have two ovens. There has been endless discussion about what to get. Do you get two identical ovens? Seems like a missed opportunity. Do we want one of those steam ovens? No, doesn't a tray of water in the base of a normal oven do the same job...? (I would like to also reject the tonnes of different cooking programmes available on some ovens, stop the madness, no one uses them!) So we considered one electric fan oven and one gas oven? This solution seems ideal- maximum flexibility. Only a limited number of companies sell built in gas ovens and we decided to go with SMEG. Dimitri has scored maximum points for finding the SMEG outlet store. We found they had a reconditioned gas, and pyrolytic electric fan oven. We gave them a call and found out that these ovens were under a year old, and had scratches to their fascias, but nothing wrong with the technical gubbin's. We also discovered that a replacement fascia, should we need one, is about £60! So we bought the two ovens for £429 incl delivery. HOORAY!

For the hob we are going for maximum flexibility again with a standard size induction hob and two gas burners. The best priced 2- ring ceramic (which is actually black glass?!) gas hob we can find is the IKEA Möjlig. The induction hob is going to be a bit of a splurge, but as the most used appliance in the kitchen I think it's worth it. I seem to have barely any conductivity in my fingers and technology in general seems to ignore my presence. So, once I had tried the NEFF point and twist magnetic knob, I was a lost cause. Never again will I need to jab repeatedly and pointlessly at the controls.

I would like to highly recommend Sust-it, a brilliant website that allows you to compare appliance energy efficiency. We met Ross, the founder, a few years ago when we went to visit his eco house, he told us about his website. He set it up as a result of having the same issues about what appliances to put in his energy efficient home. The website has now expanded to analysing electronics in the home, motoring and travel. It is stuffed full of really good advice. It's here, as well as WHICH consumer report, where I end up when I want to find useful information.