Passive House, storms and power cuts

[Russdl]

Wasn't sure where to post this but here's our observations after storm Eunice passed through.

 

Initially we watched the storm gather, we could see that that the wind was strong but from inside there was no indication, no sound, no draughts.

 

As the wind picked up something we were not expecting happened, we could hear and feel a draught. We have two fairly large sliders and at the peak of the storm, the wind was pushing against the slider so much that there was airflow between the slider and the fixed pane. Not much and not continuous but it was definitely happening. Our air test was done to passive standards (positive and negative pressure) so we're fairly certain there is no problem with the sliders because if there was then the negative pressure test would have exposed that. Anyone have a contradictory view?

 

A short time later we had a power cut , that doesn't matter. The house is warm, the Sunamp is fully charged (minus two showers), what could go wrong?

Well, we're fully electric so there was no cup of tea to sup whilst watching the storm play out. Information gleaned is that the power will be out for over 48hrs

 

And of course there's no heating. But what does that matter because the house is toasty warm at about 21.5° and we've not had any heating on for days.

And the house is almost airtight, apart from the few blasts that squeezed through the sliders.

 

Thanks to @Adrian Walker's advice we have a CO2 monitor, well we bought a couple. It was quite amazing how quickly the CO2 PPM started to increase after the power cut. Obviously the MVHR was having a bit of "quiet time", so now we had a toasty warm passive house that was not working as planned. As night drew in it got worse because lots of candles were lit. The only solution was to open some windows and get some airflow. Out of interest, it was only the monitors that informed us of the poor air quality, it wasn't something we sensed.

 

So, we have a toasty warm passive house but with no airflow so a couple of the 'tilt and turn' windows on opposite sides of the house were tilted. That fixed things, air quality wise, very quickly but it also meant the passive house was now going to cool down more rapidly than planned. There are no heating options, apart from the bio-ethanol fire) so we were getting ready to break out the cold weather gear. Fortunately power was restored about 12 hours after the cut.

 

We have a fair amount of PV, and it was quite a sunny storm but of course the PV trips off in a power cut. We were meant to have a battery system but the that didn't happen. The M&E individual who specced that (and didn't provide) had wired in an emergency power supply from which we could run the fridge and freezer in the event of a power outage, which was a pretty smart idea, shame it never happened, but actually my advise to anyone building to passive standards, if they have a battery system then make sure that the MVHR will run off the batteries.

 

That's the main thing we've learned. If you have built to passive standard and have a battery system, make sure your MVHR  can run from the batteries in the event of a power cut, I suspect most battery systems will power an MVHR unit for ages. Without that, you're not in a passive house anymore.

 

Oh, and we had the first BBQ of the season this evening. Bit nippy!

 

Edited February 19, 2022 by Russdl

[joth]

9 hours ago, Russdl said:

Thanks to @Adrian Walker's advice we have a CO2 monitor, well we bought a couple.

We have two CO2 sensors but they're both on mains PSU and log to a PC so would be useless in a power cut. 

Having one with a display and battery certainly sounds sensible.

 

Also I've considered a small UPS for the network router and switch. Adding the MVHR onto it would actually be fairly easy as they're both in the loft. 

[ProDave]

In our first self build 18 years ago we had not long moved in when there was a big storm.  We were sat in the living room that had a pair of double glazes sliders, watching the glass in those physically bend inwards with each gust of wind.  We then decided it might be better to go and sit in the other room without such a set of doors, just in case.  They never did fail, but the amount they were bending was surprising. 

 

Our wood burning stove would produce all the heat we need in a prolonged power cut and we have an LPG gas hob that would boil the kettle and do enough cooking.  We would have to use a box of matches to light the hob without power.

[Ferdinand]

The "solar pv power in a power cut" is one that I have been reflecting on. Need to think about what the requirements are - do the rectifiers need a power supply themselves?

 

The other mini thing I have in place is a couple of chunky phase change cooling blocks n the freezer which will keep it cooler for longer. These were supplied. No idea how they are specced, but total mass is 2.5kg.

[Ferdinand]

11 hours ago, Russdl said:

Wasn't sure where to post this but here's our observations after storm Eunice passed through.

 

So, we have a toasty warm passive house but with no airflow so a couple of the 'tilt and turn' windows on opposite sides of the house were tilted. That fixed things, air quality wise, very quickly but it also meant the passive house was now going to cool down more rapidly than planned. There are no heating options, apart from the bio-ethanol fire) so we were getting ready to break out the cold weather gear. Fortunately power was restored about 12 hours after the cut.

 

 

Can one not open the passive cat flap?

[JohnMo]

I bought a petrol generator 9kVA, for £800 from Hyundai, just got a changeover switch from Amazon for £40.  Ran my armoured 6mm2 cable out to the shed, just need the electrician to wire it all up.

 

That should keep the basics up and running and hopefully the PV will work when it sees the 230v.

[MikeSharp01]

11 hours ago, Russdl said:

Our air test was done to passive standards (positive and negative pressure) so we're fairly certain there is no problem with the sliders because if there was then the negative pressure test would have exposed that. Anyone have a contradictory view?

Slightly! The +ve and -ve air tests are quite tame (60 Pascals (pa) either way) by comparison to a 90mph gale hitting the window. I think - my first coffee is only just settling in, that a back of fag packet tells me that a 90mph gust hitting a 6m² window has a dynamic pressure of around 900 pa or 20 Ibs/ft²  or around 500Kg pushing on the window. 

[bgmill]

Having suffered a few long (24hrs+) power cuts over the last 10 years we've specced a battery along with an emergency circuit to power fridge/freezer, MVHR and some lighting. Somebody suggested that a cheaper option is a natural gas standby generator (we have a gas connection but will be switching to full electric in the new build). Anyone gone down this route?

[SteamyTea]

11 hours ago, Russdl said:

we're fully electric so there was no cup of tea to sup whilst watching the storm play out.

The village I work in had an area without power last night.

One slightly distraught customer came in at closing time. We had nothing left.

Told her to get the camping stove out.

"I have 80 guests" was the reply.

Was one of the local hotels.

BBQ for them then.

And Cornflakes for breakfast in the best Seventh Day Adventist tradition.

Edited February 19, 2022 by SteamyTea

[MikeSharp01]

8 minutes ago, SteamyTea said:

Told her to get the camping stove out.

Cook out to help out - why not? Get the food out of their fridges and cook it on your prems, or invite the residents for breakfast at your place - best good Samaritan tradition. 

[SteamyTea]

20 minutes ago, MikeSharp01 said:

Cook out to help out - why not? Get the food out of their fridges and cook it on your prems, or invite the residents for breakfast at your place - best good Samaritan tradition. 

We know the true cost of helping out. It can quickly ruin a reputation, just not worth it.

 

[JohnMo]

3 hours ago, bgmill said:

Somebody suggested that a cheaper option is a natural gas standby generator (we have a gas connection but will be switching to full electric in the new build). Anyone gone down this route?

Priced and checked running cost, then went petrol

[epsilonGreedy]

@Russdldo you recall specific CO2 ppm numbers as the air quality declined?

[Onoff]

15 hours ago, Russdl said:

We have a fair amount of PV, and it was quite a sunny storm but of course the PV trips off in a power cut. We were meant to have a battery system but the that didn't happen. The M&E individual who specced that (and didn't provide) had wired in an emergency power supply from which we could run the fridge and freezer in the event of a power outage, which was a pretty smart idea, shame it never happened, but actually my advise to anyone building to passive standards, if they have a battery system then make sure that the MVHR will run off the batteries.

 

If it's all wired up ready for it can't you just add batteries now?

 

This reminds me I must phone my mate, he offered me his "old" battery system a while back.

 

When I say old it's more a case he got mugged off as he always does. Had a PV system already then was sold batteries basically by door knockers. Someone only has to say "new technology" and he'll stump up. Can't be that silly as he's on the high FiT rate but paid through the nose to start with. 

[Omnibuswoman]

8 minutes ago, Onoff said:

 

This reminds me I must phone my mate, he offered me his "old" battery system a while back.

 

I need more friends like this guy!!

[Onoff]

12 minutes ago, Omnibuswoman said:

 

I need more friends like this guy!!

 

Stuff he's given me off the top of my head:

 

-2200W dust extractor.

-His old uPVC front door is my new back door.

-Picture frame guillotine.

-Velux he never fitted.

-Elliot pillar drill

-Wet tile cutter

-Various steel sections

-Garage shelving

-1983 Ford Capri

 

I think often it's stuff he gets hold of and doesn't have the space for!

 

Works both ways. When the main switch in his vintage skeleton cu burnt out one night I was there in the early hours to repair. Always giving him steel, little leccy bits and latterly 3D printing stuff. We go back 45 years. 

 

 

 

[Russdl]

5 hours ago, joth said:

Having one with a display and battery certainly sounds sensible.

They’re pretty useful, they sit downstairs plugged into the mains and recharging during the day and come upstairs at nighttime. They monitor CO2, RH and Temperature. 

 

 

 

 

4 hours ago, MikeSharp01 said:

a 90mph gust hitting a 6m² window has a dynamic pressure of around 900 pa or 20 Ibs/ft²  or around 500Kg pushing on the window. 

I’ll take your word for that, there was definitely a lot of pressure. 
 

38 minutes ago, epsilonGreedy said:

do you recall specific CO2 ppm numbers as the air quality declined?

According to the monitors the highest we got to was 1247PPM, it was the red light and the sad face on the display that alerted us. Our ‘normal’ level is around 6-700PPM (green light, smiley face on the display)

 

17 minutes ago, Onoff said:

 

If it's all wired up ready for it can't you just add batteries now?

Yep we could.
 

Slight cash flow issue at the moment but when the CCJ is paid (I’m sure he will, why wouldn’t he do what a Court tells him to do?) then we’ll get the batteries. 

 

 

[Russdl]

5 hours ago, Ferdinand said:

The other mini thing I have in place is a couple of chunky phase change cooling blocks n the freezer which will keep it cooler for longer. These were supplied. No idea how they are specced, but total mass is 2.5kg.

We have those as well. Instructions are to place them at the top of the freezer in a power cut. We opted to not open the freezer door. No idea how long they would maintain the temperature or what is in them. 
 

 

[ProDave]

In our last house we had a power cut lasting many days after a storm.

 

When we came to examine it of course just about everything in the freezer had thawed. but surprisingly little got wasted as most of the thawed stuff got cooked in one mammoth session and then re frozen as ready meals.

[Ferdinand]

6 hours ago, Russdl said:

We have those as well. Instructions are to place them at the top of the freezer in a power cut. We opted to not open the freezer door. No idea how long they would maintain the temperature or what is in them. 
 

 

 

Where would you keep them cold if not already in the freezer ?.

 

Adding warm blocks after a power cut would thaw it out more quickly in my physics !

 

Mine live at the top and only get taken out for a picnic or if eg I'm going shopping elsewhere and need to keep eg coastally purchased fish cold for an extended period. 

[Ferdinand]

7 hours ago, JohnMo said:

Priced and checked running cost, then went petrol

 

I have a standby generator for my heating.

 

It is a Super Ser.

[Russdl]

14 minutes ago, Ferdinand said:

 

Where would you keep them cold if not already in the freezer ?.

Ours live in the bottom of the freezer and we didn’t move them to the top like wot we shoulda done. 

[dpmiller]

I note that the comments negating the likelihood of outages *aren't* coming from folk that live out in the sticks where power is HV *and* LV overhead...

[Onoff]

20 minutes ago, dpmiller said:

I note that the comments negating the likelihood of outages *aren't* coming from folk that live out in the sticks where power is HV *and* LV overhead...

 

Quite amazed we didn't lose power here over the last couple of days. I was TT but I'm now apparently PME according to the sticker the DNO applied to my head last time a tree took out the overhead to the house. 

[dpmiller]

ours has been off for a number of hours (3-12) three times since we got the mains connected.