// Numbas version: finer_feedback_settings
{"name": "Calculate savings from installing a heat pump", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Calculate savings from installing a heat pump", "tags": [], "metadata": {"description": "", "licence": "None specified"}, "statement": "<p data-start=\"0\" data-end=\"52\">Calculate the savings from installing a heat pump.</p>\n<p data-start=\"54\" data-end=\"62\">Given:</p>\n<ul data-start=\"63\" data-end=\"402\" data-is-last-node=\"\">\n<li data-start=\"63\" data-end=\"126\">Natural gas consumption: <strong data-start=\"90\" data-end=\"111\">{gas_consumption}</strong>kWh per year</li>\n<li data-start=\"127\" data-end=\"167\">Boiler efficiency: <strong data-start=\"148\" data-end=\"165\">{boiler_eff}%</strong></li>\n<li data-start=\"168\" data-end=\"294\">Coefficient of performance (COP) of heat pump: <strong data-start=\"217\" data-end=\"240\">{coeff_performance}</strong> (units of heat output per unit of electrical input)</li>\n<li data-start=\"295\" data-end=\"340\">Cost of gas: <strong data-start=\"310\" data-end=\"332\">{cost_gas_kWh*100}</strong>p/kWh</li>\n<li data-start=\"341\" data-end=\"402\" data-is-last-node=\"\">Cost of electricity: <strong data-start=\"364\" data-end=\"394\">{cost_electricity_kWh*100}</strong>p/kWh</li>\n</ul>", "advice": "<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Heat requirement</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></p>\n<ul>\n<li><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{gas_consumption}kWh x {boiler_eff}% = {precround(heat_req,3)}kWh</span></li>\n</ul>\n<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Electricity needed to generate the same amount of heat</span></strong></p>\n<ul>\n<li><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{heat_req}/{coeff_performance} (CoP) = {precround(electricity_req,3)}kWh</span></li>\n</ul>\n<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Cost of electricity </span></strong></p>\n<ul>\n<li><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{precround(electricity_req,3)}kWh x &pound;{cost_electricity_kWh} = &pound;{precround(total_cost_electricity,3)}</span></li>\n</ul>\n<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Cost of gas </span></strong></p>\n<ul>\n<li><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{precround(gas_consumption,3)}kWh x &pound;{cost_gas_kWh} = &pound;{precround(total_cost_gas,3)}</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></li>\n</ul>\n<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Savings</span></strong></p>\n<ul>\n<li><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&pound;{precround(total_cost_gas,3)} - &pound;{precround(total_cost_electricity,3)} = &pound;{precround({total_cost_gas - total_cost_electricity},3)}</span></li>\n</ul>", "rulesets": {}, "extensions": [], "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true, "j": false}, "constants": [], "variables": {"gas_consumption": {"name": "gas_consumption", "group": "Ungrouped variables", "definition": "random(200000 .. 600000#10000)", "description": "<p>Consumption of natural gas in kWh per anum.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "coeff_performance": {"name": "coeff_performance", "group": "Ungrouped variables", "definition": "random(3 .. 4#0.1)", "description": "<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Coefficient of performance, units of heat output</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">for units of electrical </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">input.</span></p>", "templateType": "randrange", "can_override": false}, "boiler_eff": {"name": "boiler_eff", "group": "Ungrouped variables", "definition": "random(60 .. 90#5)", "description": "<p>Boiler efficiency in %.</p>", "templateType": "randrange", "can_override": false}, "heat_req": {"name": "heat_req", "group": "Ungrouped variables", "definition": "gas_consumption*boiler_eff/100", "description": "<p>Variable to store heat requirement calculation.</p>", "templateType": "anything", "can_override": false}, "electricity_req": {"name": "electricity_req", "group": "Ungrouped variables", "definition": "heat_req/coeff_performance", "description": "<p>Variable to store electricity requirement calculation.</p>", "templateType": "anything", "can_override": false}, "total_cost_electricity": {"name": "total_cost_electricity", "group": "Ungrouped variables", "definition": "electricity_req*cost_electricity_kwh", "description": "<p>Variable to store the total cost of electricity calculation.</p>", "templateType": "anything", "can_override": false}, "total_cost_gas": {"name": "total_cost_gas", "group": "Ungrouped variables", "definition": "gas_consumption*cost_gas_kwh", "description": "<p>Variable to store the total cost of gas calculation.</p>", "templateType": "anything", "can_override": false}, "cost_electricity_kwh": {"name": "cost_electricity_kwh", "group": "Ungrouped variables", "definition": "random(0.08 .. 0.15#0.01)", "description": "<p>The cost of electricity per kWh in &pound;'s.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "cost_gas_kwh": {"name": "cost_gas_kwh", "group": "Ungrouped variables", "definition": "random(0.02 .. 0.06#0.01)", "description": "<p>The cost of gasper kWh in &pound;'s.&nbsp;</p>", "templateType": "randrange", "can_override": false}}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": ["gas_consumption", "coeff_performance", "boiler_eff", "heat_req", "electricity_req", "total_cost_electricity", "total_cost_gas", "cost_electricity_kwh", "cost_gas_kwh"], "variable_groups": [], "functions": {}, "preamble": {"js": "", "css": ""}, "parts": [{"type": "numberentry", "useCustomName": false, "customName": "", "marks": 1, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<div class=\"TextLayer-container\">\n<div class=\"textLayer\"><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Hints: first work out how much electricity you need to</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">generate the heat</span><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">requirement.</span>\n<div class=\"endOfContent textLayer--absolute\"></div>\n</div>\n</div>", "minValue": "total_cost_gas - total_cost_electricity", "maxValue": "total_cost_gas - total_cost_electricity", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": "2", "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": false, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}], "partsMode": "all", "maxMarks": 0, "objectives": [], "penalties": [], "objectiveVisibility": "always", "penaltyVisibility": "always", "contributors": [{"name": "Simon Stuttaford", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/26443/"}], "resources": []}]}], "contributors": [{"name": "Simon Stuttaford", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/26443/"}]}