{"id":1449,"date":"2012-11-11T15:08:28","date_gmt":"2012-11-11T15:08:28","guid":{"rendered":"http:\/\/paulaowenconsulting.co.uk\/?p=1449"},"modified":"2015-10-28T17:13:02","modified_gmt":"2015-10-28T17:13:02","slug":"the-hidden-cost-of-efficient-electric-induction-hobs","status":"publish","type":"post","link":"https:\/\/greengumption.co.uk\/live\/2012\/11\/the-hidden-cost-of-efficient-electric-induction-hobs\/","title":{"rendered":"A story of induction hobs, electricity monitors & standby power consumption"},"content":{"rendered":"

Update January 2014: Before you read on, I need to make it clear that my induction hob DOES NOT actually use the amount of standby electricity that it appears to in this article.\u00a0 I eventually tracked the problem down to an issue with the electricity Real Time\u00a0Display meter (RTD), otherwise known as electrcity monitors,\u00a0I was using to monitor my electrcity consumption.\u00a0 Electricity real-time display meters do not cope well with appliances that have an inductive load – such as an induction hob, and consequently\u00a0display the wrong, higher,\u00a0power consumption as a result.\u00a0 This is explained in detail in the update blog post I wrote subsequently and provide a link to at end of this article. I write this update\u00a0as this blog post has been read over 35,000 times in a year and many readers are not reading the update to the story – hence are thinking induction hobs are really bad.\u00a0 THEY ARE NOT!\u00a0\u00a0So please, if you read this article, be sure to read the next in the series, that explains what is actually\u00a0going on. <\/strong><\/p>\n

I do not want to remove this article as many people are finding this article because they have discovered the same ‘problem’ when using electricity meters to monitor consumption,\u00a0hence I want to leave the story as it unfolded for me, so others can understand the ‘problem’, which is actually\u00a0with the power monitor\u00a0 not being able to cope with inductive loads, not the hob.<\/strong><\/p>\n

November 2012<\/p>\n

I moved into my home some years ago and immediately set about refurbing the kitchen which was in a shocking state.\u00a0 One kitchen appliance\u00a0I had been coveting for a long while was an electric\u00a0induction hob.\u00a0\u00a0In my opinion it was\u00a0a\u00a0much more\u00a0practical\u00a0appliance\u00a0than\u00a0its gas fueled equivalent, with all its different bits that are tricky to keep clean and that\u00a0persistent, nagging\u00a0worry of whether you left the gas on or not.\u00a0\u00a0More importantly, the induction hob is promoted as a very efficient way to cook, being around 30% more efficient than other types of electric hob.\u00a0 At the time they were still a niche product, and relatively expensive to purchase compared to gas and other electric hobs, but I saw it as an investment.<\/p>\n

So I went ahead and\u00a0bought\u00a0one from a very\u00a0well respected, German\u00a0manufacturer of kitchen appliances, and it was love at first use.\u00a0 The induction hob is an absolute joy to cook with.\u00a0 It is instantly responsive, it has a easy wipe-clean glass surface, you cannot accidently leave it on\u00a0and there are no twiddly\u00a0knobs or buttons, just a simple, minimalist,\u00a0touch sensitive control\u00a0panel embedded into the glass itself.\u00a0 Although expensive I didn’t regret my purchase for a moment, and\u00a0I was\u00a0sure in the knowledge\u00a0that\u00a0I had also made an energy efficient purchase (at the time\u00a0I was thinking ahead to when I would install PV, so my hob\u00a0cooking would be both cost and carbon free eventually).<\/p>\n

Later on,\u00a0I was testing out a range of ‘Real Time Display’ (RTD)\u00a0products for work, these are\u00a0devices you attach to your electricity meter\u00a0that give you minute by minute information on your electricity usage.\u00a0 I then did exactly\u00a0what people typically do when first\u00a0installing an RTD,\u00a0I went around the house, turning one gadget off after another, to see exactly how much power my individual\u00a0appliances and gadgets\u00a0were consuming.<\/p>\n

It soon became apparent that there was something\u00a0using rather a large amount of background\u00a0power, and\u00a0I couldn’t easily track it down!\u00a0 Everything\u00a0with a plug attached\u00a0was switched off, including the fridge-freezer, and still there was about a 70-80 Watt\u00a0(W) residual\u00a0consumption.\u00a0 Eventually\u00a0I twigged – the only thing I hadn’t switched off at the mains\u00a0was the induction hob.\u00a0 Luckily the red isolation switch for the hob is easily accessible, and as soon as\u00a0I turned it off, my RTD showed almost zero.<\/p>\n

Imagine my shock?!\u00a0 My wonderful, seemingly energy efficient induction hob was burning through a huge amount of power when it was, ostensibly, doing absolutely nothing! I was horrified, and checked, then double checked, my findings with a range of RTDs at my disposal. They all displayed the same bad news – my beloved hob was hugely wasteful in ‘standby’ mode.<\/p>\n

At an average consumption of\u00a075 W, and, by my calculation, taking off\u00a0an average of one hour’s worth of actual usage a day which is a tad generous, in standby for 23 hours per day,\u00a0I calculated my hob was using 1.8 kWh\/day.\u00a0 This was costing me, at an average electricity unit price of 14.5pence, nearly \u00a3100 a year to run, when it wasn’t doing anything useful!<\/p>\n

The other finding was, as my entire annual electricity use was only\u00a0approximately 1800 kWh\/year (as calculated through my electricity bill), that my hob, whilst ‘idling’, was responsible for one third of my entire electricity consumption.<\/p>\n

My “cunning”\u00a0solution to this problem\u00a0was to keep switching the hob off at the isolation switch, both overnight and\u00a0we left the house\u00a0each day.\u00a0 This worked well for about a fortnight,\u00a0 but after that\u00a0 my hob suddenly\u00a0stopped working!\u00a0 There was nothing for it but to call out an engineer and luckily my hob was still under guarantee.\u00a0 An engineer duly\u00a0turned up\u00a0and expressed surprise that such a new, typically\u00a0reliable appliance should suddenly go ‘kaput’ just like that.\u00a0\u00a0I acted as\u00a0innocently as I could\u00a0and did not reveal I was switching it off each day as\u00a0I guessed that might have invalidated the warrantee.\u00a0 He fixed it, and\u00a0I decided that it wasn’t too\u00a0wise to\u00a0continue switching it off daily especially as I was coming to the end of my warrantee period, so I just decided to swallow the extraordinarily high running cost.<\/p>\n

Roll forward to the\u00a0present day.\u00a0 Since installing PV panels\u00a0over a year ago\u00a0I have been monitoring both\u00a0my electricity use and production carefully through the use of my PV enabled Wattson RTD\u00a0meter, which gives me graphical breakdowns of total usage by minute, hour, day and month.\u00a0 What\u00a0I have noticed over the last\u00a0twelve months is a gradual increase in my typical daily usage of electricity; even though we have not added any new appliances to the mix and are as careful as ever with our usage.\u00a0 So, for example,\u00a0instead of the typical 1800 kWh\/year total consumption, I am now looking at around an estimated 2200 kWh\/year\u00a0over the past 12 months according to my Wattson real time display meter.<\/p>\n

My first thought was that our\u00a06 year old\u00a0fridge-freezer was deteriorating in performance, so\u00a0I checked that – no joy there.\u00a0 I also checked our base load consumption (with hob switched off) when we were away on holiday for a week, that turned out to be\u00a0a reasonable\u00a01.6 kWh\/day.\u00a0 Then we went through the house, turning off one product at a time to see if we could identify the culprit – still\u00a0no luck!\u00a0 Until, yes you guessed it, we\u00a0arrived to the hob.\u00a0 Now, I was used to the hob’s\u00a070-80W consumption pattern, so was expecting to see that level of reduction but, imagine my shock yet again when the RTD\u00a0meter dropped by around 150W when we switched it off?!\u00a0 We tested this thoroughly, and when we next\u00a0went away we left the hob on, to check background consumption.\u00a0 Sure enough, background usage as monitored by the RTD, over a\u00a024 hour period\u00a0with no-one at home, but with the hob left on, was around a total\u00a0electrcity use\u00a0of\u00a05.5 kWh.\u00a0 This means it is now\u00a0using around 1200 kWh\/year whilst idling, inexplicably\u00a0the appliance seems to have suddenly deteriorated in performance?<\/p>\n

Scaled up\u00a0over a year, and\u00a0with a new annual total\u00a0electricity usage pattern\u00a0of 2200 kWh, it appears to mean my hob is now responsible for\u00a0over half my entire electricity\u00a0consumption and is costing me \u00a3150 a year whilst doing absolutely nothing except waiting for me to come and turn it on through the touch sensitive control\u00a0panel.<\/p>\n

At that extraordinaily high\u00a0running cost,\u00a0I thought I’d look online to see if it would be worth my while buying a new, truly efficient model, but the problem is, as far as\u00a0I can ascertain, no manufacturer currently\u00a0displays the ‘standby’ function energy consumption in their publicly available\u00a0product details for hobs.\u00a0 Electric hobs will be soon coming under the EU\u00a0energy label jurisdiction, and that\u00a0does have a requirement for any ‘standby’ mode not to\u00a0have a higher consumption load than 0.5W.\u00a0My worry is if the mode that my hob sits in whilst waiting to be turned on at the touch control is defined and\u00a0labelled something other than ‘standby’ mode, for example ‘quick start’ mode or something similar, then manufacturers can legally\u00a0by-pass the standby requirement and continue to produce such inefficient appliances.<\/p>\n

Please follow this link<\/a> for an update on this issue.\u00a0 The effect I was seeing on my electricity display meter \u00a0(RTD) is not actually real, and the electricity usage of my hob in standby mode\u00a0is actually\u00a0MUCH LESS\u00a0than what I describe here due to a phenomenon known as the ‘power factor’.<\/strong><\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Update January 2014: Before you read on, I need to make it clear that my induction hob DOES NOT actually use the amount of standby electricity that it appears to in this article.\u00a0 I eventually tracked the problem down to an issue with the electricity Real Time\u00a0Display meter (RTD), otherwise known as electrcity monitors,\u00a0I was […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"class_list":{"0":"post-1449","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-energy-efficiency"},"_links":{"self":[{"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/posts\/1449","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/comments?post=1449"}],"version-history":[{"count":1,"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/posts\/1449\/revisions"}],"predecessor-version":[{"id":1705,"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/posts\/1449\/revisions\/1705"}],"wp:attachment":[{"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/media?parent=1449"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/categories?post=1449"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/greengumption.co.uk\/live\/wp-json\/wp\/v2\/tags?post=1449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}