Visiting a Passive House

Visiting a Passive House

Today I went and stepped inside my first passive house....or two!! I signed up to the Nearly Zero Energy Buildings - Open Doors Ireland event which has been held for the last few years. A number of willing residents open their doors for visitors like me to come poking around and asking lots and lots of questions! The hosts were great and very patient! You can find out more here:

http://www.nzeb-opendoors.ie

Some of the houses have attached websites / blogs you can access to get more in depth information and inspiration for your own build.

One of the first things that struck me was how quiet it was. With all the rain and wind outside, there was no way of noticing it once you stepped inside and closed the door! A summary of items I found interesting from each house is as follows:

House #1 - Newbridge:

This was a build in progress. As time and money allow Seamus was working on the inside now the building was air tight and sealed. I took a LOT of notes as he pointed out each detail and explained how each was progressing and challenges faced along the way. The H shape was very interesting but it increased the cost and challenged the PHPP software! He recommended the 2/3 day Passive House course to get some additional info prior to building and understand how the PHPP calculations work. The course is @ €300 for the 3 days.

As the house wasn't finished it was great to get handed examples of the materials used and see into the building which when finished of course hides much of the magic.

He noted his triple glazed windows and door were Passive House certified at the time of purchase but since then the manufacturer hasn't kept up payments to the Passive House Organization and has been dropped from their Database...they still work fine though!

Seamus recommended illbruck TP600 for sealing around windows etc rather than Flexifoam he used (if using foam make sure it's specifically for windows). The only thing is the speed at which the window has to be installed after the product is let "loose" as it expands quickly to fill the space. It's breathable, weather sealant and provides Thermal and acoustic insulation. Good tip!

Getting a good windows installer is tricky - some suppliers just don't understand how to deal with a passive house so ask for the companies best installers and insist they are the only ones allowed onsite. The weight of the doors can be a problem so check hinges are able to take the weight, they may need to be upgraded if the company chosen are not familiar with the loads. Windows can bend if the wrong foam is used as the pressure is different at various points of the frame, not good for doors especially as you get gaps. This is one clear area where precision to avoid thermal bridging is important.

Prices for Windows is around €500 per sq meter, halve that if you have a very solid building - timber flexes by 13% but with the reinforcing Seamus had put it it's only 6% so he could put in rebates into the building window openings to take the glass directly without a window frame! Saved half the cost that way. The spacers in the windows he got were thermal and dark coloured. The right stuff in other words! Don't forget to ask about Low-e!

Seamus is keeping the PV panels supplying DC instead of inverting it to AC and using the power to look after a 500 litre storage heater for hot water and the rads. He reckons if you're paying more than €1 per kW for the panels then you're being overcharged - so for 1kW you'd need 4 panels and it should only cost €1,000.

Solar Panels for heating water - a drainback system empties the panel when not in use. This avoids systems that use Glycol which can turn to sludge in very hot weather if turned off and needs cleaning out. It's also acidic in that state.

His LEDs are "homemade" - he had a panel with 4 set up, two Sharp LEDs, an off the shelf LED and a Halogen for comparison to show how he made them up and the differences in colour temperature. The Sharp CRI value showed the best light after the Halogen and only uses 9 (vs 50) volts. He bought the LEDs, mountings and heatsinks and soldered / glued them ( in that order) himself. The electronics in a standard LED are compressed to make them like traditional Halogens but they also have to keep things cool, not so eazy - Seamus reckons the lifespan of those off the shelf LEDs are not too good as a result. He used a separate box to drive the electronics and can connect up to 5 LEDs to achieve a much longer life solution @ 50,000 hours all going well!

His rainwater harvesting solution is based on a 2,000 litre concrete tank. He has designed his own control unit which uses a header tank. If the rainwater is low it switches to mains. If you're heading out on holidays to avoid untreated water getting stale and smelly while you're away you can force a mains water flush to put chlorine into the header and leave it there until you come back and then revert. Very smart! The commercial equivalent is €700-800, his was €200! Plus he reckons the pumps they use are too powerful so he's sourcing a smaller 12v one.

He's also designing a leak detector to turn off the mains water and placing it beside the immersion tank.

For KNX he's going to use a binary device from ABB - this negates the need to buy expensive light switches, basically the box is the brains and you don't need fancy sockets or switches, use ordinary ones! The KNX switches are €70 a pop otherwise!

House #2 - Enniskerry:

This was a finished Passive House and again was very quiet, although we were in the country! The warmth was lovely and even though they'd cooked a fry earlier there was no smell. The Mechanical Heat Recovery unit was interested to see, very, very simple, dishwasher safe! And it works! They've two of them and rarely use the underfloor heating. I didn't recognize the hot water system but it was also well insulated and works well for them.

They had large windows but an overhang to prevent overheating - they find the Spring and Autumn are the warmest months when the sunlight is able to get right in! The back door had to have the hinges replaced as they were too weak and the supplier also didn't apply UV treatment on the windows which had to be done later to prevent deterioration.

Their Electric bill is €150 every 2 months all in, mine is the same but you should see my gas bill!!! The only thing is the internal sound - it's very easy for noise to pass through the walls so if going timber frame and you have more than one person in the house, or kids, pay attention and get extra sound proofing. Also if you've upstairs / downstairs pay attention there also.

The design was fabulous - the huge living room set of windows was really something from a showhouse!

Update: Forgot to add, the owner noted that keeping fruit lying around wasn't possible due to the temperature, something I hadn't thought of. They have an interesting porch that is outside the insulated envelope they use to come in from outside, shed wet shoes / clothes etc so a similar cold room might be an idea for food storage. Other methods include cellars but with a Passive Slab I doubt this is possible.

Well, I hope you found some of this interesting. I'm not planning any more trade shows / visits but am talking to Architects myself at the moment to start the design and planning. I expect it will take a while to firm up the detail but start slow is my advice, changes now are much easier before things get locked in!