// Numbas version: finer_feedback_settings
{"name": "Carbon Footprinting Quiz", "metadata": {"description": "", "licence": "None specified"}, "duration": 0, "percentPass": 0, "showQuestionGroupNames": false, "shuffleQuestionGroups": false, "showstudentname": true, "question_groups": [{"name": "Group", "pickingStrategy": "all-ordered", "pickQuestions": 1, "questionNames": ["", "", "", "", "", ""], "variable_overrides": [[], [], [], [], [], []], "questions": [{"name": "Calculate carbon footprint and energy use per unit floor area", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "contributors": [{"name": "Simon Stuttaford", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/26443/"}], "tags": [], "metadata": {"description": "<p>The student must calculate the carbon footprint given electricity and gas energy usage.</p>", "licence": "None specified"}, "statement": "<div class=\"textLayer\">\n<p data-start=\"0\" data-end=\"68\">Calculate the carbon footprint and energy use per unit floor area.</p>\n<p data-start=\"70\" data-end=\"78\">Given:</p>\n<ul data-start=\"79\" data-end=\"258\">\n<li data-start=\"79\" data-end=\"134\">Electricity use: <strong data-start=\"98\" data-end=\"119\">{electricity_use}</strong>kWh per year</li>\n<li data-start=\"135\" data-end=\"182\">Natural gas use: <strong data-start=\"154\" data-end=\"167\">{gas_use}</strong>kWh per year</li>\n</ul>\n<p data-start=\"260\" data-end=\"274\">Assumptions:</p>\n<ul data-start=\"275\" data-end=\"436\" data-is-last-node=\"\">\n<li data-start=\"275\" data-end=\"348\">Carbon emissions from gas: <strong data-start=\"304\" data-end=\"331\">{gas_carbon_kg_per_kWh}</strong> kg CO\u2082 per kWh</li>\n<li data-start=\"349\" data-end=\"436\" data-is-last-node=\"\">Carbon emissions from electricity: <strong data-start=\"386\" data-end=\"421\">{electricity_carbon_kg_per_kWh}</strong> kg CO\u2082 per kWh</li>\n</ul>\n</div>", "advice": "<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Carbon footprint for electricity</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{electricity_use}kWh x {electricity_carbon_kg_per_kWh}kg/kWh = {electricity_use*electricity_carbon_kg_per_kWh}kg</span></p>\n<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></p>\n<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"><strong>Carbon footprint for gas</strong><br role=\"presentation\" class=\"textLayer--absolute\"/>&bull; {gas_use}kWh x {gas_carbon_kg_per_kWh}kg/kWh = {gas_use*gas_carbon_kg_per_kWh}kg</span></p>\n<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></p>\n<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"><strong>Total carbon footprint</strong><br role=\"presentation\" class=\"textLayer--absolute\"/>&bull; {electricity_use*electricity_carbon_kg_per_kWh}kg + {gas_use*gas_carbon_kg_per_kWh}kg = {(electricity_use*electricity_carbon_kg_per_kWh) + (gas_use*gas_carbon_kg_per_kWh)}kg</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></p>\n<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"><br role=\"presentation\" class=\"textLayer--absolute\"/><strong>Elec usage per m<sup>2</sup></strong><br role=\"presentation\" class=\"textLayer--absolute\"/>&bull; {electricity_use}kWh / {floor_area}m<sup>2 </sup>= {precround(dec(electricity_use/floor_area),3)}kWh/m<sup>2</sup></span></p>\n<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></p>\n<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"><strong>Gas usage per m<sup>2</sup></strong><br role=\"presentation\" class=\"textLayer--absolute\"/>&bull; {gas_use}kWh / {floor_area}m<sup>2 </sup>= {precround(dec(gas_use/floor_area),3)}kWh/m<sup>2</sup><br/></span></p>", "rulesets": {}, "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true, "j": false}, "constants": [], "variables": {"electricity_use": {"name": "electricity_use", "group": "Parts a-c group", "definition": "random(50000 .. 200000#1)", "description": "<p>Electricity use in KWh per year.</p>", "templateType": "randrange", "can_override": false}, "gas_use": {"name": "gas_use", "group": "Parts a-c group", "definition": "random(150000 .. 500000#1)", "description": "<div class=\"TextLayer-container\">\n<div class=\"textLayer\"><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Natural gas use in kWh per year</span><br role=\"presentation\" class=\"textLayer--absolute\" /><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></div>\n</div>", "templateType": "randrange", "can_override": false}, "gas_carbon_kg_per_kWh": {"name": "gas_carbon_kg_per_kWh", "group": "Parts a-c group", "definition": "random(0.15 .. 0.21#0.001)", "description": "<p>Kilograms of CO2 produced per kWh of energy.&nbsp;</p>", "templateType": "randrange", "can_override": true}, "electricity_carbon_kg_per_kWh": {"name": "electricity_carbon_kg_per_kWh", "group": "Parts a-c group", "definition": "random(0.46 .. 0.2#0.001)", "description": "<p>Kilograms of CO2 produced per kWh of energy.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "total_carbon_footprint": {"name": "total_carbon_footprint", "group": "Parts a-c group", "definition": "(electricity_use * electricity_carbon_kg_per_kwh) + (gas_use * gas_carbon_kg_per_kwh)", "description": "<p>Variable that stores the quantity of CO2 in Kg.&nbsp;</p>", "templateType": "anything", "can_override": false}, "floor_area": {"name": "floor_area", "group": "Parts a-c group", "definition": "random(1000 .. 4000#100)", "description": "<p>Area of floor in metres squared.&nbsp;</p>", "templateType": "randrange", "can_override": false}}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": [], "variable_groups": [{"name": "Parts a-c group", "variables": ["gas_use", "electricity_carbon_kg_per_kWh", "gas_carbon_kg_per_kWh", "total_carbon_footprint", "electricity_use", "floor_area"]}], "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": "<p>Calculate the total carbon footprint in kgs.&nbsp;</p>", "minValue": "total_carbon_footprint", "maxValue": "total_carbon_footprint", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": false, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"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": "<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Using the information above, calculate your </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">energy use per unit floor area for electricity. Floor area &ndash; {floor_area}m<sup>2</sup></span></p>", "minValue": "{electricity_use / floor_area}", "maxValue": "{electricity_use / floor_area}", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": false, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"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": "<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Using the information above, calculate your </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">energy use per unit floor area for gas. Floor area &ndash; {floor_area}m<sup>2</sup></span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"><sup></sup></span></p>", "minValue": "{gas_use / floor_area}", "maxValue": "{gas_use / floor_area}", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "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"}, {"name": "How many kiloWatt-hours does your boiler use each year?", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "contributors": [{"name": "Simon Stuttaford", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/26443/"}], "tags": [], "metadata": {"description": "", "licence": "None specified"}, "statement": "<div class=\"TextLayer-container\">\n<ul></ul>\n<div class=\"endOfContent textLayer--absolute\">\n<p data-start=\"0\" data-end=\"57\">How many kilowatt-hours does your boiler use each year?</p>\n<p data-start=\"59\" data-end=\"67\">Given:</p>\n<ul data-start=\"68\" data-end=\"462\" data-is-last-node=\"\">\n<li data-start=\"68\" data-end=\"130\"><strong data-start=\"70\" data-end=\"101\">{operational_days_per_year}</strong> operational days in a year</li>\n<li data-start=\"131\" data-end=\"190\">Two boilers, each with a power of <strong data-start=\"167\" data-end=\"185\">{boiler_power}</strong>kW</li>\n<li data-start=\"191\" data-end=\"299\">One boiler runs at full power for <strong data-start=\"227\" data-end=\"248\">{hot_water_hours}</strong> hour(s) every day all year (supplying hot water)</li>\n<li data-start=\"300\" data-end=\"462\" data-is-last-node=\"\">Both boilers run at an average of <strong data-start=\"336\" data-end=\"364\">{average_power_percent}%</strong> power for an additional <strong data-start=\"389\" data-end=\"414\">{space_heating_hours}</strong> hours per day for half the year (space heating)</li>\n</ul>\n</div>\n</div>", "advice": "<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Hot water Consumption</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> {boiler_power}</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">kW x {hot_water_hours}hr x {operational_days_per_year}days = {hot_water_consumption}kWh</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&nbsp;</span><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Space Heating Consumption</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> {boiler_power*2}</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">kW x {average_power_percent}% x {space_heating_hours}hrs x {operational_days_per_year/2}days = {space_heating_consumption}kWh</span><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Total Energy Consumption</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{hot_water_consumption}kWh + {space_heating_consumption}kWh = {total_energy_consumption}kWh = {dec(total_energy_consumption/1000)}Mwh</span></p>", "rulesets": {}, "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true, "j": false}, "constants": [], "variables": {"operational_days_per_year": {"name": "operational_days_per_year", "group": "Ungrouped variables", "definition": "random(200 .. 300#10)", "description": "<p>The number of days the boilers are operational during the year.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "boiler_power": {"name": "boiler_power", "group": "Ungrouped variables", "definition": "random(100 .. 300#50)", "description": "<p>The power of each boiler in kilowatts.&nbsp;</p>", "templateType": "randrange", "can_override": true}, "hot_water_hours": {"name": "hot_water_hours", "group": "Ungrouped variables", "definition": "random(1 .. 3#1)", "description": "<p>The hours per day one boiler runs at full power to supply hot water.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "space_heating_hours": {"name": "space_heating_hours", "group": "Ungrouped variables", "definition": "random(5 .. 9#1)", "description": "<p style=\"text-align: left;\">The hours per day both boilers run to supply space heating.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "average_power_percent": {"name": "average_power_percent", "group": "Ungrouped variables", "definition": "random(50 .. 80#5)", "description": "<p>The average power both boilers run at to supply space heating.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "hot_water_consumption": {"name": "hot_water_consumption", "group": "Ungrouped variables", "definition": "boiler_power*hot_water_hours*operational_days_per_year", "description": "<p>Variable to store the answer for hot water consumption during the period in kWh.&nbsp;</p>", "templateType": "anything", "can_override": false}, "space_heating_consumption": {"name": "space_heating_consumption", "group": "Ungrouped variables", "definition": "boiler_power*2*(average_power_percent/100)*space_heating_hours*(operational_days_per_year/2)", "description": "<p>Variable to store the answer for space heating consumption during half of the operational period in kWh.&nbsp;</p>", "templateType": "anything", "can_override": false}, "total_energy_consumption": {"name": "total_energy_consumption", "group": "Ungrouped variables", "definition": "hot_water_consumption+space_heating_consumption", "description": "<p>Variable to store the answer for the total energy consumption over the period in kWh.&nbsp;</p>", "templateType": "anything", "can_override": false}}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": ["operational_days_per_year", "boiler_power", "hot_water_hours", "space_heating_hours", "average_power_percent", "hot_water_consumption", "space_heating_consumption", "total_energy_consumption"], "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": "<p>Calculate the hot water energy consumption during the period in kWh.&nbsp;</p>", "minValue": "hot_water_consumption", "maxValue": "hot_water_consumption", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": false, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"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": "<p>Calculate the space heating energy consumption during the period in kWh.&nbsp;</p>", "minValue": "space_heating_consumption", "maxValue": "space_heating_consumption", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": false, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"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": "<p>Calculate the total energy consumption during the period in kWh.&nbsp;</p>", "minValue": "total_energy_consumption", "maxValue": "total_energy_consumption", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "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"}, {"name": "How much heat loss (in W) will you save by insulating your building\u2019s walls and windows?", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "contributors": [{"name": "Simon Stuttaford", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/26443/"}], "tags": [], "metadata": {"description": "", "licence": "None specified"}, "statement": "<div class=\"TextLayer-container\">\n<div class=\"textLayer\">\n<p data-start=\"0\" data-end=\"262\">How much heat loss (in watts) will you save by insulating your building&rsquo;s walls and windows if you improve the wall U-value from <strong data-start=\"129\" data-end=\"151\">{old_wall_u_value}</strong> to <strong data-start=\"155\" data-end=\"177\">{new_wall_u_value}</strong>, and the window U-value from <strong data-start=\"207\" data-end=\"231\">{old_window_u_value}</strong> to <strong data-start=\"235\" data-end=\"259\">{new_window_u_value}</strong>?</p>\n<p data-start=\"264\" data-end=\"272\">Given:</p>\n<ul data-start=\"273\" data-end=\"446\" data-is-last-node=\"\">\n<li data-start=\"273\" data-end=\"306\">Wall area: <strong data-start=\"286\" data-end=\"301\">{wall_area}</strong>m&sup2;</li>\n<li data-start=\"307\" data-end=\"344\">Window area: <strong data-start=\"322\" data-end=\"339\">{window_area}</strong>m&sup2;</li>\n<li data-start=\"345\" data-end=\"395\">Indoor temperature: <strong data-start=\"367\" data-end=\"391\">{inside_temperature}</strong>&deg;C</li>\n<li data-start=\"396\" data-end=\"446\" data-is-last-node=\"\">Outdoor temperature: <strong data-start=\"419\" data-end=\"444\">{outside_temperature}</strong>&deg;C</li>\n</ul>\n</div>\n</div>", "advice": "<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Heat loss from walls before insulation</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{wall_area}m</span><sup><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">2</span></sup><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">x {old_wall_u_value}(u-value) x {inside_temperature - outside_temperature}(temp diff in kelvin) = {old_wall_heat_loss}W</span><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Heat loss from walls after insulation</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> {wall_area}</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">m<sup>2</sup></span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> x {new_wall_u_value}(u-value) x {inside_temperature - outside_temperature}(temp diff in kelvin) </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&nbsp;= {new_wall_heat_loss}W</span><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Heat loss saving from wall insulation</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{old_wall_heat_loss}W - {new_wall_heat_loss} W = {total_savings_wall}W</span></p>\n<p><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></p>\n<p><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Heat loss from windows before insulation</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{window_area}m</span><sup><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">2</span></sup><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">x {old_window_u_value}(u-value) x {inside_temperature - outside_temperature}(temp diff in kelvin) = {old_window_heat_loss}W</span><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Heat loss from windows after insulation</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> {window_area}</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">m<sup>2</sup></span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> x {new_window_u_value}(u-value) x {inside_temperature - outside_temperature}(temp diff in kelvin) </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&nbsp;= {new_window_heat_loss}W</span><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Heat loss saving from window insulation</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&bull;</span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{old_window_heat_loss}W - {new_window_heat_loss} W = {total_savings_window}W</span></p>\n<p></p>", "rulesets": {}, "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true, "j": false}, "constants": [], "variables": {"outside_temperature": {"name": "outside_temperature", "group": "Ungrouped variables", "definition": "random(-10 .. 10#5)", "description": "<p>Outside air temperature in Celsius.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "inside_temperature": {"name": "inside_temperature", "group": "Ungrouped variables", "definition": "random(15 .. 25#5)", "description": "<p>Inside air temperature in Celsius.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "wall_area": {"name": "wall_area", "group": "Ungrouped variables", "definition": "random(150 .. 500#50)", "description": "<p>Wall surface area in metres squared.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "old_window_u_value": {"name": "old_window_u_value", "group": "Ungrouped variables", "definition": "random(3.5 .. 6#0.1)", "description": "<p>U-value of window prior to insulating.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "new_window_u_value": {"name": "new_window_u_value", "group": "Ungrouped variables", "definition": "random(2.5 .. 1.1#0.1)", "description": "<p>U-value of window after insulating.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "new_wall_u_value": {"name": "new_wall_u_value", "group": "Ungrouped variables", "definition": "random(0.4 .. 1.6#0.1)", "description": "<p>U-value of wall after insulating.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "old_wall_u_value": {"name": "old_wall_u_value", "group": "Ungrouped variables", "definition": "random(1.9 .. 2.5#0.1)", "description": "<p>U-value of wall prior to insulating.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "old_wall_heat_loss": {"name": "old_wall_heat_loss", "group": "Ungrouped variables", "definition": "wall_area*old_wall_u_value*(inside_temperature - outside_temperature)", "description": "<p>The heat loss of the old wall prior to insulation, in Watts.</p>", "templateType": "anything", "can_override": false}, "new_wall_heat_loss": {"name": "new_wall_heat_loss", "group": "Ungrouped variables", "definition": "wall_area*new_wall_u_value*(inside_temperature-outside_temperature)", "description": "<p>The heat loss of the new wall prior to insulation, in Watts.</p>", "templateType": "anything", "can_override": false}, "window_area": {"name": "window_area", "group": "Ungrouped variables", "definition": "random(50 .. 250#50)", "description": "<p>Area of windows in metres squared.&nbsp;</p>", "templateType": "randrange", "can_override": true}, "old_window_heat_loss": {"name": "old_window_heat_loss", "group": "Ungrouped variables", "definition": "window_area*old_window_u_value*(inside_temperature-outside_temperature)", "description": "<p>The heat loss of the old windows prior to insulation, in Watts.</p>", "templateType": "anything", "can_override": false}, "new_window_heat_loss": {"name": "new_window_heat_loss", "group": "Ungrouped variables", "definition": "window_area*new_window_u_value*(inside_temperature-outside_temperature)", "description": "<p>The heat loss of the new windows after insulation, in Watts.</p>", "templateType": "anything", "can_override": false}, "total_savings_wall": {"name": "total_savings_wall", "group": "Ungrouped variables", "definition": "old_wall_heat_loss-new_wall_heat_loss", "description": "<p>Total energy savings from insulating wall, in Watts.</p>", "templateType": "anything", "can_override": false}, "total_savings_window": {"name": "total_savings_window", "group": "Ungrouped variables", "definition": "old_window_heat_loss-new_window_heat_loss", "description": "<p>Total energy savings from new windows, in Watts.</p>", "templateType": "anything", "can_override": false}}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": ["outside_temperature", "inside_temperature", "wall_area", "old_window_u_value", "new_window_u_value", "new_wall_u_value", "old_wall_u_value", "old_wall_heat_loss", "new_wall_heat_loss", "window_area", "old_window_heat_loss", "new_window_heat_loss", "total_savings_wall", "total_savings_window"], "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": "<p>Heat loss saving from wall insulation in Watts.&nbsp;</p>", "minValue": "total_savings_wall", "maxValue": "total_savings_wall", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": true, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"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": "<p>Heat loss saving from new insulated windows in Watts.&nbsp;</p>", "minValue": "total_savings_window", "maxValue": "total_savings_window", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": 0, "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": true, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}], "partsMode": "all", "maxMarks": 0, "objectives": [], "penalties": [], "objectiveVisibility": "always", "penaltyVisibility": "always"}, {"name": "Calculate the financial and carbon cost each year to turn the heating up", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "contributors": [{"name": "Simon Stuttaford", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/26443/"}], "tags": [], "metadata": {"description": "", "licence": "None specified"}, "statement": "<div class=\"TextLayer-container\">\n<div class=\"textLayer\">\n<p data-start=\"0\" data-end=\"155\">Calculate the extra financial cost and carbon emissions over a year if the heating is increased from <strong data-start=\"101\" data-end=\"122\">{temperature_low}</strong>&deg;C to <strong data-start=\"128\" data-end=\"150\">{temperature_high}</strong>&deg;C.</p>\n<p data-start=\"157\" data-end=\"165\">Given:</p>\n<ul data-start=\"166\" data-end=\"508\" data-is-last-node=\"\">\n<li data-start=\"166\" data-end=\"208\">Total gas use: <strong data-start=\"183\" data-end=\"202\">{total_gas_use}</strong>kWh</li>\n<li data-start=\"209\" data-end=\"285\">Space heating accounts for <strong data-start=\"238\" data-end=\"266\">{percent_space_heating}%</strong> of total gas use</li>\n<li data-start=\"286\" data-end=\"401\">A <strong data-start=\"290\" data-end=\"297\">1&deg;C</strong> increase in temperature adds <strong data-start=\"327\" data-end=\"370\">{percent_increase_heating_consumption}%</strong> to space heating consumption</li>\n<li data-start=\"402\" data-end=\"442\">Gas price: <strong data-start=\"415\" data-end=\"434\">{gas_price*100}</strong>p/kWh</li>\n<li data-start=\"443\" data-end=\"508\" data-is-last-node=\"\">Gas carbon emissions: <strong data-start=\"467\" data-end=\"493\">{carbon_emissions_gas}</strong> kg CO\u2082 per kWh</li>\n</ul>\n<br/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"></span></div>\n</div>", "advice": "<div class=\"textLayer\">\n<div class=\"TextLayer-container\">\n<div class=\"textLayer\"><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Rise in gas consumption</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{total_gas_use}kWh x {percent_increase_heating_consumption}% = {gas_consumption_increase}kWh</span></div>\n<div class=\"textLayer\"><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Cost of extra gas consumption</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{gas_consumption_increase}kWh x &pound;{gas_price}/kWh = &pound;{extra_cost_gas_consumption}</span></div>\n<div class=\"textLayer\"><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Carbon emissions of extra gas</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{gas_consumption_increase}kWh x {carbon_emissions_gas}kg/kWh = {extra_carbon_gas_consumption}kg</span>\n<div class=\"endOfContent textLayer--absolute\"></div>\n</div>\n</div>\n</div>\n<div class=\"textLayer\"></div>", "rulesets": {}, "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true, "j": false}, "constants": [], "variables": {"temperature_low": {"name": "temperature_low", "group": "Ungrouped variables", "definition": "temperature_high - 1", "description": "<p>Lower temperature in celsius.&nbsp;</p>", "templateType": "anything", "can_override": false}, "total_gas_use": {"name": "total_gas_use", "group": "Ungrouped variables", "definition": "random(300000 .. 500000#10000)", "description": "<p>Total gas use in kWh.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "percent_space_heating": {"name": "percent_space_heating", "group": "Ungrouped variables", "definition": "random(60 .. 95#5)", "description": "<p>Percentage of total gas use that is space heating.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "percent_increase_heating_consumption": {"name": "percent_increase_heating_consumption", "group": "Ungrouped variables", "definition": "random(3 .. 15#1)", "description": "<p>Increase to space heating consumption after a one degree rise, in percent.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "gas_price": {"name": "gas_price", "group": "Ungrouped variables", "definition": "random(0.03 .. 0.07#0.001)", "description": "<p>The price of gas in &pound;'s.&nbsp;</p>", "templateType": "randrange", "can_override": false}, "carbon_emissions_gas": {"name": "carbon_emissions_gas", "group": "Ungrouped variables", "definition": "random(0.15 .. 0.2#0.001)", "description": "<div class=\"TextLayer-container\">\n<div class=\"textLayer\"><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Gas carbon emissions, kg CO2 per kWh.</span>\n<div class=\"endOfContent textLayer--absolute\"></div>\n</div>\n</div>", "templateType": "randrange", "can_override": false}, "gas_consumption_increase": {"name": "gas_consumption_increase", "group": "Ungrouped variables", "definition": "total_gas_use*percent_increase_heating_consumption/100", "description": "<p>Variable to store the rise in gas consumption calculation.</p>", "templateType": "anything", "can_override": false}, "extra_cost_gas_consumption": {"name": "extra_cost_gas_consumption", "group": "Ungrouped variables", "definition": "gas_consumption_increase*gas_price", "description": "<p>Variable to store the cost of extra gas consumption calculation.</p>", "templateType": "anything", "can_override": false}, "extra_carbon_gas_consumption": {"name": "extra_carbon_gas_consumption", "group": "Ungrouped variables", "definition": "gas_consumption_increase*carbon_emissions_gas", "description": "<p>Variable to store the carbon emissions of extra gas consumption calculation.</p>", "templateType": "anything", "can_override": false}, "temperature_high": {"name": "temperature_high", "group": "Ungrouped variables", "definition": "random(18 .. 21#1)", "description": "<p>Higher temperature in celsius.&nbsp;</p>", "templateType": "randrange", "can_override": false}}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": ["temperature_low", "total_gas_use", "percent_space_heating", "percent_increase_heating_consumption", "gas_price", "carbon_emissions_gas", "gas_consumption_increase", "extra_cost_gas_consumption", "extra_carbon_gas_consumption", "temperature_high"], "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": "<p>Cost of extra gas consumption, in &pound;:</p>", "minValue": "extra_cost_gas_consumption", "maxValue": "extra_cost_gas_consumption", "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": true, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"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": "<p>Carbon emissions of extra gas, in kg:</p>", "minValue": "extra_carbon_gas_consumption", "maxValue": "extra_carbon_gas_consumption", "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": true, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}], "partsMode": "all", "maxMarks": 0, "objectives": [], "penalties": [], "objectiveVisibility": "always", "penaltyVisibility": "always"}, {"name": "Calculate savings from installing a heat pump", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "contributors": [{"name": "Simon Stuttaford", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/26443/"}], "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": {}, "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"}, {"name": "Calculate annual savings from turning desktop IT off outside of working hours", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "contributors": [{"name": "Simon Stuttaford", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/26443/"}], "tags": [], "metadata": {"description": "", "licence": "None specified"}, "statement": "<div class=\"TextLayer-container\">\n<div class=\"textLayer\">\n<p data-start=\"0\" data-end=\"84\">Calculate the annual savings from turning desktop IT off outside of working hours.</p>\n<p data-start=\"86\" data-end=\"94\">Given:</p>\n<ul data-start=\"95\" data-end=\"340\">\n<li data-start=\"95\" data-end=\"165\"><strong data-start=\"97\" data-end=\"118\">{percent_pcs_on}%</strong> of <strong data-start=\"122\" data-end=\"138\">{number_pcs}</strong> PCs are left on <strong data-start=\"155\" data-end=\"163\">24/7</strong></li>\n<li data-start=\"166\" data-end=\"223\">Each PC consumes <strong data-start=\"185\" data-end=\"209\">{pc_power_idle*1000}</strong> W when idle</li>\n<li data-start=\"224\" data-end=\"284\"><strong data-start=\"226\" data-end=\"245\">{hours_working}</strong>-hour working day, <strong data-start=\"264\" data-end=\"273\">5-day</strong> workweek</li>\n<li data-start=\"285\" data-end=\"340\">Electricity cost: <strong data-start=\"305\" data-end=\"332\">{price_electricity*100}</strong> p/kWh</li>\n</ul>\n<p data-start=\"342\" data-end=\"416\" data-is-last-node=\"\"><em data-start=\"342\" data-end=\"416\" data-is-last-node=\"\">Hint: In this calculation, it's fine to have a fractional number of PCs.</em></p>\n</div>\n</div>", "advice": "<div class=\"TextLayer-container\">\n<div class=\"textLayer\"><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\"> </span><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Energy consumed by one PC running 24/7</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{pc_power_idle}kW x 24h x 365d = {single_pc_power_247}kWh</span></div>\n<div class=\"textLayer\"><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Energy consumed during working hours</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{pc_power_idle}kW x {hours_working}h x 5d x 52weeks = {single_pc_power_working_hours}kWh</span></div>\n<div class=\"textLayer\"><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Wasted energy</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{single_pc_power_247}kWh - {single_pc_power_working_hours}kWh = {wasted_energy}kWh</span></div>\n<div class=\"textLayer\"><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Cost saving for each PC</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">{wasted_energy}kWh x &pound;{price_electricity}/kWh = &pound;{single_pc_savings}</span></div>\n<div class=\"textLayer\"><br role=\"presentation\" class=\"textLayer--absolute\"/><strong><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">Cost saving for {dec(number_pcs*percent_pcs_on/100)} PCs</span></strong><br role=\"presentation\" class=\"textLayer--absolute\"/><span role=\"presentation\" dir=\"ltr\" class=\"textLayer--absolute\">&pound;{single_pc_savings} x {dec(number_pcs*percent_pcs_on/100)} = &pound;{total_cost_savings}</span>\n<div class=\"endOfContent textLayer--absolute\"></div>\n</div>\n</div>", 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