// Numbas version: finer_feedback_settings
{"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}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "How much heat loss (in W) will you save by insulating your building\u2019s walls and windows?", "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": {}, "extensions": [], "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 - 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