31:T594,md`# About saving energy We’ve all learned that we can save energy by taking shorter showers and switching off all lights. And to close doors so the heating doesn’t have to work so hard. But do these things actually matter in the big picture? How much energy do we use at home? For this I've pulled some numbers out of my lower back (since I could not find very precise numbers ^†). I’ve tried to look for estimates for Europe in areas with kind of cold winters. Basic assumptions are: - Heating is with gas. Homes commonly have central heating. - Electricity is used for hot water (often a big hot water cylinder) and cooking. - Air conditioning for cooling is uncommon (very hot summers were unusual until recently). A sort of normal energy bill is about 1500 m³ of gas and 3500 kWh of electricity per year. So let’s match these numbers below. *A caveat about comparing electricity usage figures between countries: these depend a lot on whether or not it is common to use electricity for space heating. The amount of energy used for heating completely dwarfs the typical 3,500 kWh electricity bill.* We also have to talk about **cars**. It turns out you pour a lot of fuel in these things during a year. *An electric car cruising at 100 km/h uses about 15 kW. To draw this much power from a 240 V mains grid you need a connection rated for over 60 A.*`32:[] 2f:{"title":"About saving energy","cells":[{"id":0,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":254,"value":"md`## settings`","pinned":false,"hidden":false,"mode":"ojs"},{"id":9,"value":"viewof gas_m3 = Range([0, 3000], {value: 1500, step: 100, label: \"Heating (m³ of gas)\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":13,"value":"viewof car_km_1000 = Range([0, 40], {value: 20, step: 1, label: \"Cars (1000’s of km)\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":115,"value":"viewof hot_water_1000l = Range([0, 60], {value: 30, step: 1, label: html`Hot water
(1000’s of l)`})","pinned":false,"hidden":false,"mode":"ojs"},{"id":108,"value":"viewof cooking = Range([0, 1000], {value: 500, step: 10, label: \"Cooking (kWh)\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":128,"value":"viewof appliances = Range([0, 3000], {value: 1500, step: 10, label: \"Appliances and lights (kWh)\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":104,"value":"viewof misc = Range([0, 200], {value: 100, step: 10, label: \"Other (kWh)\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":22,"value":"chart.node","pinned":false,"hidden":false,"mode":"ojs"},{"id":892,"value":"bar_chart.node","pinned":false,"hidden":false,"mode":"ojs"},{"id":422,"value":"viewof car_l_100km = Range([3, 15], {value: 7, step: .5, label: \"Car l/100km\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":1261,"value":"viewof car_kWh_100km = Range([10, 25], {value: 15, step: 1, label: \"El. car kWh/100km\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":1271,"value":"viewof heat_pump_cof = Range([2, 5], {value: 3, step: 0.1, label: \"Heat pump COP\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":206,"value":"viewof electrify = Checkbox([\"Cars\", \"Heating\"], { label: \"Electrify:\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":234,"value":"viewof use_heat_for_electric_l = Checkbox([\"Convert electricity to heat for electricity generation\"], {value: []})","pinned":false,"hidden":false,"mode":"ojs"},{"id":356,"value":"md`## So, what are the big energy hogs?`","pinned":false,"hidden":false,"mode":"ojs"},{"id":303,"value":"md`OK, so it turns out switching off lights ^‡ and short showers don’t matter all that much.\n\n\nThe first two things that actually matter are:\n\n - Driving. Especially petrol cars, but even electric cars use a lot of energy.\n - Heating. That central heating is very comfortable, but it costs. Closing doors probably matters.\n\nAfter these two, start thinking about shorter showers.\n\n*Driving 10 km (at 7 l / 100 km) uses about 6.5 kWh. That is enough energy to heat up 120 l of hot water by 45 °C, enough for a few very long hot showers.*\n\n-----------`","pinned":false,"hidden":false,"mode":"ojs"},{"id":985,"value":"md`^†: Some numbers I did find:\n\n\nYou can find rough numbers left and right, eg:\n\n - a general breakdown of energy use in Europe: https://ec.europa.eu/eurostat/statistics-explained/index.php/Energy_consumption_in_households\n\n - Hot water use in Belgium: https://document.environnement.brussels/opac_css/elecfile/IF%20Energie%20ECS01%20part%20NL\n\n - various averages for gas use for heating. 1500 m³ seems a common estimate.\n\n - vecicle kilometres driven per year in Belgium: we drive a bit over 7,000 km per year per capita: https://mobilit.belgium.be/nl/mobiliteit/mobiliteit_cijfers/kilometers_door_belgische_voertuigen\n\n----------`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1006,"value":"md`^‡: To be fair, lights used to be a bigger deal than it is now. Back in the day we used incancescent lamps. These were not very efficient and lighting a living room could easily take more than 100 W. You could easily waste a couple of kWh per day leaving lights on.\n\n----------`","pinned":false,"hidden":false,"mode":"ojs"},{"id":398,"value":"md`## Recipe`","pinned":false,"hidden":false,"mode":"ojs"},{"id":20,"value":"chart = {\n const svg = d3.create(\"svg\")\n .attr(\"viewBox\", [0, 0, width, chart_size]);\n \n var chart = { node:svg.node() };\n chart.defs = svg.append(\"defs\");\n \n var g = svg.append(\"g\").attr('transform', `translate(${chart_size / 2 + chart_left_pad}, ${chart_size / 2})`);\n \n chart.pie_g = g.append(\"g\");\n chart.text_g = g.append(\"g\")\n .attr(\"font-size\", 14)\n .attr(\"font-weight\", \"bold\")\n .attr(\"text-anchor\", \"middle\");\n \n return chart;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":948,"value":"bar_chart = {\n const svg = d3.create(\"svg\")\n .attr(\"viewBox\", [0, 0, width, 60]);\n \n var bar_chart = {node:svg.node()};\n \n var bar_chart = { node:svg.node() };\n bar_chart.defs = svg.append(\"defs\");\n\n // group for stacked bar\n bar_chart.g_bars = svg.append(\"g\");\n\n var unit = 'kWh';\n \n // Add scales to axis\n var x_axis = d3.axisBottom()\n .scale(bar_scale)\n .tickFormat(x => (x == 0) ? `${x}\\u00a0${unit}` : x);\n\n //Append group and insert axis\n svg.append(\"g\").attr(\"transform\", `translate(${bar_margin}, 40)`)\n .call(x_axis);\n \n return bar_chart;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":56,"value":"chart_update = {\n // Pie chart\n \n chart.defs.selectAll(\"*\").remove();\n for (const d of data) {\n if (d.calorific)\n {\n chart.defs.append(x => mk_fill(\"hatch-\"+d.calorific, d.color, use_heat_for_electric));\n }\n }\n\n chart.pie_g\n .selectAll(\"path\")\n .data(pie)\n .join(\"path\")\n .attr(\"fill\", d => d.data.calorific ? \"url(#hatch-\" + d.data.calorific + \")\" : d.data.color)\n .attr(\"stroke\", \"#fff\")\n .attr(\"stroke-linejoin\", \"round\")\n .attr(\"stroke-width\", 1.2)\n .attr(\"d\", d => inflate(d.data) ? arc_2(d) : arc(d))\n .call(s => s.select(\"title\").remove())\n .append(\"title\")\n .text(d => `${d.data.name}: ${d.data.kWh} kWh`);\n \n chart.text_g\n .selectAll(\"text\")\n .data(pie)\n .join(\"text\")\n .attr(\"style\", \"text-shadow: rgba(255, 255, 255, .5) 1px 1px 1px\")\n .attr(\"transform\", d => `translate(${txt_arc.centroid(d)})`)\n .attr(\"fill\", \"black\")\n .attr(\"y\", d => d.data.txt_y || \"-0.4em\")\n .text(d => d.data.name);\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":956,"value":"bar_chart_update = {\n bar_chart.defs.selectAll(\"*\").remove();\n for (const d of data) {\n if (d.calorific)\n {\n bar_chart.defs.append(x => mk_fill(\"hatch-\"+d.calorific, d.color, use_heat_for_electric));\n }\n }\n\n\n bar_chart.g_bars.selectAll(\"rect\")\n .data(stacked)\n .join(\"rect\")\n .attr(\"fill\", d => d.data.calorific ? \"url(#hatch-\" + d.data.calorific + \")\" : d.data.color)\n .attr(\"stroke\", \"#fff\")\n .attr(\"stroke-linejoin\", \"round\")\n .attr(\"stroke-width\", 1.2)\n .attr(\"x\", d => d.x + bar_margin)\n .attr(\"y\", d => inflate(d.data) ? 7.5 : 0.5)\n .attr(\"width\", d => d.w)\n .attr(\"height\", d => inflate(d.data) ? 32 : 39)\n .call(s => s.select(\"title\").remove())\n .append(\"title\")\n .text(d => `${d.data.name}: ${d.data.kWh} kWh`);\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":1236,"value":"inflate = d => use_heat_for_electric && !d.calorific","pinned":true,"hidden":false,"mode":"ojs"},{"id":633,"value":"md`### Data`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1046,"value":"use_heat_for_electric = use_heat_for_electric_l.length > 0","pinned":true,"hidden":false,"mode":"ojs"},{"id":403,"value":"average_calorific_correction =\n data.map(to_kWh).reduce((a, b) => a + b, 0) /\n data.map(d => d.kWh).reduce((a, b) => a + b, 0)","pinned":true,"hidden":false,"mode":"ojs"},{"id":29,"value":"data = [\n electrify.includes(\"Heating\") ?\n {name:\"Heating (heat pump)\", kWh: gas_kWh_per_m3 * gas_m3 / heat_pump_cof, color:\"#fd0\"} :\n {name:\"Heating (gas)\", kWh: gas_kWh_per_m3 * gas_m3, color:\"#fd0\", calorific: \"heat\"},\n electrify.includes(\"Cars\") ?\n {name:\"Driving (electric)\", kWh: 10 * car_kWh_100km * car_km_1000, color:\"#f3a\"} :\n {name:\"Driving (gasoline)\", kWh: 10 * car_l_100km * petrol_kWh_per_litre * car_km_1000, color:\"#f45\", calorific: \"drive\"},\n {name:\"Hot water\", kWh: hot_water_1000l * water_kWh_per_1000l, color:\"#88f\", txt_y:\".1em\"},\n {name:\"Cooking\", kWh: cooking, color:\"#3dd\", txt_y:\".1em\"},\n {name:\"Appliances\", kWh: appliances, color:\"#3f9\"},\n {name:\"Other\", kWh: misc, color:\"#7b7\", is_other:1, txt_y:\"-1.1em\"},\n];","pinned":true,"hidden":false,"mode":"ojs"},{"id":902,"value":"stacked = {\n var l = [];\n var x = 0;\n for (var d of data)\n {\n var w = bar_scale(to_kWh(d));\n l.push({data:d, x:x, w:w});\n x += w;\n }\n return l;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":628,"value":"md`### Shapes`","pinned":false,"hidden":false,"mode":"ojs"},{"id":62,"value":"pie = d3.pie().value(to_kWh)\n .sort(null)(data)","pinned":true,"hidden":false,"mode":"ojs"},{"id":37,"value":"arc = d3.arc()\n .innerRadius(chart_size * .25)\n .outerRadius(chart_size * .5)","pinned":true,"hidden":false,"mode":"ojs"},{"id":1214,"value":"arc_2 = d3.arc()\n .innerRadius(chart_size * .28)\n .outerRadius(chart_size * .5)","pinned":true,"hidden":false,"mode":"ojs"},{"id":377,"value":"txt_arc = d3.arc()\n .innerRadius(chart_size * .35)\n .outerRadius(chart_size * .4);","pinned":true,"hidden":false,"mode":"ojs"},{"id":438,"value":"md`### Magic numbers`","pinned":false,"hidden":false,"mode":"ojs"},{"id":225,"value":"// Heat from combustion is not directly equivalent to electricity.\n// The efficiency of fuel power plants is about 50% so sometimes\n// a kWh of electricity actually comes from about 2 kWh worth of\n// fossil fuel.\ncalorific_correction_factor = 2","pinned":true,"hidden":false,"mode":"ojs"},{"id":214,"value":"// according to Wikipedia\npetrol_kWh_per_litre = 9.3","pinned":true,"hidden":false,"mode":"ojs"},{"id":435,"value":"// approximately, depends on gas composition and on season\ngas_kWh_per_m3 = 10","pinned":true,"hidden":false,"mode":"ojs"},{"id":972,"value":"// We’re assuming we’re heating up by 45°, eg. 15 to 60 degrees.\nwater_kWh_per_1000l = 4184 / 3.6e6 * 45 * 1000","pinned":true,"hidden":false,"mode":"ojs"},{"id":223,"value":"to_kWh = d => (inflate(d) ? calorific_correction_factor : 1) * d.kWh","pinned":true,"hidden":false,"mode":"ojs"},{"id":497,"value":"md`### Chart`","pinned":true,"hidden":false,"mode":"ojs"},{"id":78,"value":"chart_size = Math.min(width - chart_left_pad, 400)","pinned":true,"hidden":false,"mode":"ojs"},{"id":522,"value":"chart_left_pad = 15","pinned":true,"hidden":false,"mode":"ojs"},{"id":928,"value":"bar_margin = 20","pinned":true,"hidden":false,"mode":"ojs"},{"id":937,"value":"bar_scale = d3.scaleLinear()\n .domain([0, 40e3])\n .range([0, width - bar_margin*2]);","pinned":true,"hidden":false,"mode":"ojs"},{"id":270,"value":"function mk_fill(id, color, use_heat)\n{\n var fill = use_heat ? .6 : .4;\n var t = HatchTile45({size: 5, fill: fill, id:id, fg:color, bg:d3.interpolate(color, \"white\")(.85)});\n return svg`${t.svg()}`; \n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":571,"value":"svg``","pinned":false,"hidden":false,"mode":"ojs"},{"id":496,"value":"md`### Import`","pinned":true,"hidden":false,"mode":"ojs"},{"id":5,"value":"d3 = require(\"d3\")","pinned":true,"hidden":false,"mode":"ojs"},{"id":7,"value":"import { Range, Toggle, Checkbox } from \"@observablehq/inputs\"","pinned":true,"hidden":false,"mode":"ojs"},{"id":817,"value":"import { HatchTile45 } from \"@roelandschoukens/svg-tiled-pattern-fills\"","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W32","stdlib":"1","titling":"auto"}