{"id":2342,"date":"2024-02-27T09:47:13","date_gmt":"2024-02-27T09:47:13","guid":{"rendered":"https:\/\/heatpumpingtechnologies.org\/annex62\/?page_id=2342"},"modified":"2025-09-12T15:02:56","modified_gmt":"2025-09-12T15:02:56","slug":"solarcity","status":"publish","type":"case_studies","link":"https:\/\/heatpumpingtechnologies.org\/project62\/case-studies\/solarcity\/","title":{"rendered":"SolarCity"},"content":{"rendered":"\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\"><div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \" style=\"font-size:25px\"><strong>SolarCity, Geneva<\/strong><\/p>\n<\/div><\/div>\n\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">A solar assisted heat pump in combination with unglazed solar collectors for a new mutlifamily building complex in Geneva, Switzerland.<\/p>\n<\/div>\n\n<div class=\"container\">\n<figure class=\"wp-block-image aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"440\" height=\"304\" src=\"https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013-building.png\" alt=\"\" class=\"wp-image-2343\" style=\"aspect-ratio:1.4473684210526316;width:490px;height:auto\" srcset=\"https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013-building.png 440w, https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013-building-300x207.png 300w, https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013-building-400x276.png 400w\" sizes=\"auto, (max-width: 440px) 100vw, 440px\" \/><\/figure>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \"><strong>Lessons learned&nbsp;<\/strong><\/p>\n<\/div><\/div>\n\n\n<div class=\"container container--no-margin\">\n<ul class=\"wp-block-list\">\n<li>Excellent system reliability.<\/li>\n\n\n\n<li>A single heat distribution circuit with decentralized DHW storage which does not allow for solar preheating and thus deteriorates the potential of direct solar heat production.<\/li>\n\n\n\n<li>A large part of the heat is produced at high temperature (60\u00b0C) for DHW production, decreasing the expected Seasonal Performance Factor (SPF).<\/li>\n<\/ul>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \"><strong>Key facts<\/strong><\/p>\n<\/div>\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\"><div class=\"container container--no-margin\">\n<figure class=\"wp-block-table is-style-stripes\"><table><tbody><tr><td><strong>Building<\/strong><\/td><td><\/td><td><strong>Heat Pump and Source<\/strong><\/td><td><\/td><\/tr><tr><td>Location<\/td><td><em>Geneva, Switzerland<\/em><\/td><td>Number of HP<\/td><td><em>1<\/em><\/td><\/tr><tr><td>Construction<\/td><td><em>2010<\/em><\/td><td>Installed power<\/td><td><em>30 kWth<\/em><\/td><\/tr><tr><td>Heat distribution<\/td><td><em>underfloor heating<\/em><\/td><td>Operation mode<\/td><td><em>monoenergetic<\/em><\/td><\/tr><tr><td>Heated area<\/td><td><em>927 m\u00b2<\/em> <em>(one block)<\/em><\/td><td>Heat source<\/td><td><em>unglazed solar <br>collectors<\/em><\/td><\/tr><tr><td>No. of apartments<\/td><td><em>&#8211;<\/em><\/td><td><\/td><td><\/td><\/tr><tr><td>Level of insulation<\/td><td><em>high performance<\/em><\/td><td><\/td><td><\/td><\/tr><tr><td><\/td><td><\/td><td><\/td><td><\/td><\/tr><tr><td><strong>Heating sytem<\/strong><\/td><td><\/td><td><strong>Domestic Hot Water<\/strong><\/td><td><\/td><\/tr><tr><td>Heat demand<\/td><td><em>19 kWh \/ (m\u00b2a)<\/em><\/td><td>DHW demand<\/td><td><em>48 kWh \/ (m\u00b2a)<\/em><\/td><\/tr><tr><td>Heating<br>temperature<\/td><td><em>35 \u00b0C<\/em><\/td><td>Max. temperature<\/td><td><em>60 \u00b0C<\/em><\/td><\/tr><tr><td>SH share<\/td><td><em>28 %<\/em><\/td><td>DHW share<\/td><td><em>72%<\/em><\/td><\/tr><tr><td>back-up heat <br>production<\/td><td><em>Direct electricity<\/em><\/td><td>Type of system<\/td><td><em>decentral<\/em><\/td><\/tr><tr><td><\/td><td><\/td><td>Circulation system<\/td><td><em>No<\/em><\/td><\/tr><tr><td><\/td><td><\/td><td><\/td><td><\/td><\/tr><tr><td><strong>Other information<\/strong><\/td><td><\/td><td><\/td><td><\/td><\/tr><tr><td>HP share<\/td><td><em>80%<\/em><\/td><td>COP<\/td><td><em>&#8211;<\/em><\/td><\/tr><tr><td>Direct solar heat share<\/td><td><em>19%<\/em><\/td><td>SPF<\/td><td><em>2.7<\/em><\/td><\/tr><tr><td>Back-up heat share<\/td><td><em>1%<\/em><\/td><td><\/td><td><\/td><\/tr><tr><td>Solar collectors<\/td><td><em>116 m\u00b2<\/em><\/td><td><\/td><td><\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div><\/div>\n\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">This case study concerns a coupled solar and HP system which was implemented in 2010 in a new housing complex, called SolarCity, located in Geneva (Switzerland).<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">The complex is composed of 4 buildings, each subdivided in 2 or 3 blocks, for a total of 10 blocks. The buildings present a high thermal performance envelope and a total living surface of 9\u2019552&nbsp;m\u00b2.<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">This case study concern only one of the 10 existing buildings blocks, which are all equipped with their own identical and independent heat production system.<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">The results show a very low SH demand for Switzerland and an unusually high DHW consumption, which can partly explain the relatively low HP SPF.<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \"><strong>Description of the technical concept<\/strong><\/p>\n<\/div>\n\n<div class=\"container\">\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"737\" height=\"368\" src=\"https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013-scheme.png\" alt=\"\" class=\"wp-image-2345\" srcset=\"https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013-scheme.png 737w, https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013-scheme-300x150.png 300w, https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013-scheme-400x200.png 400w\" sizes=\"auto, (max-width: 737px) 100vw, 737px\" \/><\/figure>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">The energy concept consists of solar collectors that can be used for direct solar heat production, via a heat exchanger, but are also the heat source of the HP (they are directly connected to the evaporator). Hence, when there is no solar radiation, the solar collectors work as a heat absorber on ambient air.<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">For each building block, there is: a 30&nbsp;kW<sub>th<\/sub> heat pump; 116&nbsp;m<sup>2<\/sup> of unglazed solar collectors; 2&nbsp;x 3\u2019000&nbsp;L of water for centralized heat storage with an electric rod in the storage tank in case of HP failure.<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">A specificity of the system consists in a single distribution circuit to the flats, so that SH (floor heating) and DHW cannot be supplied simultaneously and therefore are supplied alternatively. Each flat is therefore equipped with a 300&nbsp;L DHW tank. DHW distribution has priority over SH distribution, which means that when one of the 300&nbsp;L tanks is at a temperature below 40\u00b0C, the system switches automatically to DHW mode and rises the temperature of all the 300&nbsp;L tanks up to 60\u00b0C.<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">The system has 4 main operating modes, with the following priorities: (i) Direct solar heat production for SH or DHW (bypassing the HP), the surplus being used to charge the heat storage; (ii) Storage discharge, which is activated when the solar production does not reach the required distribution temperature; (iii) Activation of the HP when the storage temperature is below the required distribution temperature, with surplus production used to charge the heat storage; (iv) Direct electric heating, which is activated in case of HP failure (in particular when the evaporator temperature drops below -20\u00b0C).<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">In summer, the system can also be used for night cooling, by activating the floor distribution circuit and dissipating the heat in the solar collectors.<\/p>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"wp-block-paragraph \">Final report: DE SOUSA FRAGA, Carolina (2017). Heat pump systems for multifamily buildings: which resource for what demand? Thesis, University of Geneva. <br>Url: <a href=\"https:\/\/archive-ouverte.unige.ch\/unige:94939\">https:\/\/archive-ouverte.unige.ch\/unige:94939<\/a><\/p>\n<\/div>\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\"><div class=\"container container--no-margin\">\n<div class=\"wp-block-buttons is-horizontal is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-b989473c wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button has-custom-width wp-block-button__width-50 has-custom-font-size is-style-outline has-medium-font-size is-style-outline--1\" style=\"text-transform:none\"><a class=\"wp-block-button__link has-vivid-cyan-blue-color has-white-background-color has-text-color has-background has-text-align-center wp-element-button\" href=\"https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/ch013factsheetsolarcity.pdf\" style=\"border-radius:5px\"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"84\" class=\"wp-image-2196\" style=\"width: 300px;\" src=\"https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/fact-sheet-button-pic.png\" alt=\"\" srcset=\"https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/fact-sheet-button-pic.png 845w, https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/fact-sheet-button-pic-300x84.png 300w, https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/fact-sheet-button-pic-768x215.png 768w, https:\/\/heatpumpingtechnologies.org\/content\/uploads\/sites\/75\/2024\/02\/fact-sheet-button-pic-400x112.png 400w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/> <\/a><\/div>\n<\/div>\n<\/div>\n\n<div class=\"container container--no-margin\">\n<p class=\"has-text-align-center wp-block-paragraph \">CH013 SolarCity<\/p>\n<\/div><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>SolarCity, Geneva A solar assisted heat pump in combination with unglazed solar collectors for a new mutlifamily building complex in&#8230;<\/p>\n","protected":false},"author":41,"featured_media":0,"menu_order":0,"template":"","filters":[],"markets":[29],"applications":[7,41],"class_list":["post-2342","case_studies","type-case_studies","status-publish","hentry","markets-switzerland","applications-buildings","applications-multi-family-buildings"],"acf":[],"_links":{"self":[{"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/case_studies\/2342","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/case_studies"}],"about":[{"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/types\/case_studies"}],"author":[{"embeddable":true,"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/users\/41"}],"version-history":[{"count":3,"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/case_studies\/2342\/revisions"}],"predecessor-version":[{"id":2360,"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/case_studies\/2342\/revisions\/2360"}],"wp:attachment":[{"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/media?parent=2342"}],"wp:term":[{"taxonomy":"filters","embeddable":true,"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/filters?post=2342"},{"taxonomy":"markets","embeddable":true,"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/markets?post=2342"},{"taxonomy":"applications","embeddable":true,"href":"https:\/\/heatpumpingtechnologies.org\/project62\/wp-json\/wp\/v2\/applications?post=2342"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}