Heat Loss Overnight. Storm Ciara near worst case scenario

Calibos

I've been very pleasantly surprised while monitoring Overnight Heat-loss over the last few cold and windy nights of Storm Ciara.

2450sq/ft 1870 Victorian 2 Storey + 1/3 of Attic space converted into Bedroom with en suite. Add on house to end of Terrace so doesn't share roof with house next door as its about 2ft lower. 2ft thick solid exterior Rubble/Mortar walls. 3 open fireplaces with only 1 with a closed cast iron flap thats kept closed.

When renovated 10 years ago the ground floor was replaced with insulated concrete slab. GFCH. All 17 Windows and doors replaced with Wooden Sash DG windows from MJ. 15 of which are South and East facing so large Solar gain during the day. No Curtains on any Window/Velux, just wood Venetians Blinds). An exterior side door is open about 2 hours per day in total over the course of any given day for Dogs Winter or Summer. (Family member with somewhat compromised mobility can't or won't get up to close the door straight after dogs come back in despite complaining about the cold. What-ja-gonna-do??? LOL) Attic and converted attic space only has about 100mm fiberglass insulation between joists with attic OSB flooring over it and its not sealed from soffit vents so air can blow through it in the vaulted sloped ceiling sections around the perimetre. (Had an inconclusive thread here about a year ago discussing non destructive possible solutions to this)

Possibly because of some of the details above and despite some of the other details above, I've been very pleasantly surprised by the low rate of heat-loss overnight these last few bitter and windy nights of Storm Ciara.

Installed a HIVE Multi-zone system myself Summer of 2018 to control our Baxi Gas Boiler and Motorised Valve Downstairs, Upstairs and Hot-water Zones. Hot Water Zone is set 24/7 with the Cylinder Thermostat set to 65ºc. Downstairs Heating Zone is set for 21.5ºc from 7:30am to 11:30pm and our Upstairs Zone to 19.5ºc from 7:30am to 11:00pm (Some family members spend a lot of time in their bedrooms during the day)

Anyway. The bad Winter of 2018 before the Hive with the old non Thermostatically controlled Sunvic Schedule Timer Controller (Other than TRV's on Rads but most family members set theirs full), the Gas usage for the whole year (Includes Gas cooking year round) was 22,000kwh but for the year before which was a more average year weatherwise I imagine it was 21,000kwh. (Online Bills don't go back much further to check any earlier). This year which is the first matching period with the Summer 2018 HIVE in operation throughout, the gas consumption was 19,000kwh. So it likely saved us about €100 this year assuming the average yearly consumption used to be 21,000kwh and not the 22,000kwh of 2018 which included The Feb/March Snow and Storm Emma) and based on a 2,000kwh per year reduction will have paid for itself in 2 years as I got it when it was on sale and was able to DIY install it. So not a huge saving on the gas bills but the house is always comfortable temperature now (except when family member leaves the door open for dogs on a bitter windy winters day!! )

The subject of the thread is over-night Heat-loss though. Worst case is Windy bitter nights like Storm Ciara. Its been near zero degrees outside every morning the last few days. The Hive lets me track the over-night temperatures in a Graph. Heating goes off at 11-11:30pm and comes back on in both zones at 7:30am like I said, So these last few Windy and bitter Storm Ciara nights Downstairs went from 21.45ºc at midnight to 19.56ºc at 7:30am. So thats 1.89ºc in 7.5 hours. (dropped 0.25ºc per hour) Upstairs went from 19.35ºc at midnight to 17.25ºc at 7:30am. So thats 2.1ºc in 7.5 hours (dropped 0.28ºc per hour)

That to me sounds pretty good all things considered. Would I be right in assuming that its the Thermal mass of those 2ft thick exterior walls helping with this? Is 19,000kwh annual consumption of Gas which includes 1hr/365 days of 3-4 gas rings of cooking and 24/7/365 of hot water for a 2450sq/ft house a good number?

Sidenote: Reasonable Gas consumption probably counter balanced by atrocious electricity consumption. All lights are LED's but theres Media servers and a computer and laptop on/near 24/7, Virgin boxes on or on standby 24/7 and several 13yo Plasma TV's that refuse to die that family leave on standby and refuse to totally power down. Lecky bills were €350 every bill year round for what seemed like a decade. They've gone up the last year averaging €400-€450 which I thought was the unit price of electricity going up or something but after getting the Dec/January bill for €630!!! I investigated and it turns out the meter hasn't been read since May 2019!!!!

Calibos

Plenty of views but not much to contribute?

I was just trying to get an idea if 19,000kwh of Gas consumed per year (Including year round cooking and 24/7/365 hot water) was good going for a 2450sq/ft (227m2) house...of any vintage and if 0.25-0.28ºc per hour overnight temp drop with the heating off overnight on Stormy/Windy near 0ºc outside temp nights was good going too? The few threads I found on this particular question from similar relevant climate locations like the UK seemed to indicate that this kind of overnight temp drop was a miracle. ie maybe we just need to build houses with 100mm Loft insulation, insulated concrete groundfloor slab, Double glazed windows and..........2 Foot thick Rubble and Mortar walls un-insulated inside or out. LOL.

Yellow_Fern

Have you a blower test? The performance looks pretty good and exceeds A2 houses I have encountered.

Calibos

Yellow_Fern wrote: »

Have you a blower test? The performance looks pretty good and exceeds A2 houses I have encountered.

No, I've never had a blower test nor BER done.

Given all the issues the attic and converted attic bedroom insulation install has, the open fireplaces, a bloody exterior door being left open for a cumulative hour or two each day Winter or Summer for the dogs, (last item doesn't affect overnight temp drop rate obviously but does affect yearly gas consumption) Thats what amazes me when I cottoned on to the fact that a 0.25ºc per hour drop overnight was apparently fantastic.

Just remembered there were a few other things I did as well as the Hive over the last year.

Several of the MJ DG Wooden sashes weren't fit plumb/square by the builder and never sealed fully in the middle. and were draughty. Until I can rehang them when doing new trim work, wainscoting, window seats etc, I just temporarily filled the top and bottom sash mating gap in the middle with thick foam draught self adhesive strips.

I filled ceiling perforations around where the Gas boiler Flue penetrates the ceiling roof and where the water pipes penetrate into the attic. Soffits are effectively open to the insulated knee wall storage space alongside the attic conversion bedroom and I've merely closed the storage space door around a towel to seal the gaps to stop the gale that used to blow through the gaps between the door and frame until I can sort the insulation issues in this space and fit a properly sealing insulated door.

I replaced an en suite extractor whose exterior gravity flaps were permanently held open by a pressure differential and interior air pushing out that. Even an inline anti backdraft flap didn't work horizontally. The pressure differential held that open too. The solution was an Icon Iris Exhaust fan where there is an iris like in Stargate SG1 that closes when the fan is off. The inline backdraft flap did actually work in the ceiling mounted exhaust fan of another bathroom because where the springs weren't enough in the horizontal position to stay closed against the pressure differential, with the aid of gravity in the vertical orientation, the flap now stays closed unless the fan is on. Will replace this fan with an Icon Iris style fan too in the future though.

No damp issues anywhere in the house that I can see. Seems like the bathroom exhaust fans, the fireplaces in one bedroom and 2 downstairs and the door left open that long during the day for the dogs is providing enough air changes to keep damp and stale air at bay. The unused fireplace in the diningroom is providing the equalising outside air to feed the sometimes used fireplace in the livingroom.

Like I said, there was a lot of stuff done wrong by the builders during the renovations 10 years ago......and yet by some miracle the house is performing like an A2 for some reason. I guess large solar gain through lots of windows facing the right directions and massive thermal mass from 2ft thick walls absorbing the suns heat and GFCH heat and re-radiating it inside the house at night is the saving grace as far as our gas consumption and Night-time heatloss is concerned.

This new lower gas consumption number after a few small temporary fixes and the Hive and the slow rate of heatloss means that I'm not going to worry about the attic insulation/attic conversion bedroom kneewall storage space insulation issues from an efficiency perspective as the heat loss numbers indicates it seems to be doing alright despite the soffits being open to the insulation and blowing straight though it in the vaulted sloped ceiling sections around the perimeter. What I mean is that I was told the only way to correct the bad install that left the insulation open to the soffits but left no ventilation gap between insulation and non permeable bitumen roofing felt, was to lift the roof and replace with a permeable felt and fit a rake of vent tiles to ventilate the attic. My idea was Poopoo'd by others of DIY fabricating my own Vent cards to push down/up the vaulted sections compressing the insulation 50mm in order to better ventilate the attic and stop the gales blowing through the soffit from blowing all the warm air out of the fiberglass insulation. Was effectively told that if I didn't remove the ceilings to gain access to properly seal the vent cards to the rafters/wall plate/soffit, I was wasting my time because the warm air would still be sucked out of the insulation. Well given that as it currently stands the gales are blowing straight through the insulation already and yet I have low heatloss numbers, compressing the insulation 50mm and fitting a DIY Semi pressfit sealing vent card can only reduce the airflow through/across the insulation and improve the current situation.