The following pages will show you how to calculate the so called \u03a8g values. These linear thermal transmittances values are used to precisely calculate to energy loss to the ground. As always the calculation of the \u03a8 value is necessary to turn the simplified (surface based) U-value calculation of the buildings energy loss into a precise calculation. Omitting the calculation of these thermal bridging coefficients can therefore lead to significantly false energy calculations.<\/p>\n
It is important to understand that these \u03a8g values for the \u201cground-floor junction\u201d do not just describe the additional heat loss of the actual slab edge. \u03a8g values are used to correct the overall error made by using the simplified U-value calculations for the ground floor. Therefor it is important to note that a certain width of the floor slab has to be used for the simulation of the floor slab or basement. The \u03a8g value will only be valid for this actual width.<\/p>\n
Unfortunately, various methods are used to carry out the \u03a8g calculation. Since HTflux is used world-wide and by various types of experts (building scientists, passive house planers, architects, \u2026) it covers all calculation methods.<\/p>\n
Depending on your calculation requirements you will have to pick the method suitable for your needs. Here is an overview of the main calculation methods (click on the titles for the detailed description):<\/p>\n
The method involves the calculation of a Ug<\/sub>-value for the floor slab according to ISO13370. In HTflux the U-value<\/em> and Heatflux-tool<\/em> is used for the measurements and the PSIg-tool<\/em> is being applied for the actual calculation of the \u03a8g value.<\/p>\n The so called “option B” of ISO 10211 allows a simplified calculation of a \u03a8g value with the actual use of the Ug value defined in ISO 13370. In HTflux the U-value<\/em> and Heatflux-tool<\/em> is used for the necessary measurements and the PSIg-tool<\/em> is being applied for the calculation of the \u03a8g value.<\/p>\n This option has to be used when the slab is significantly below ground level. Similar to the Ug<\/sub>-value used for the floor slab a special Ubw<\/sub>-value has to be calculated for the wall below ground level. In HTflux the U-value<\/em> and Heatflux-tool<\/em> is used for the measurements and the PSIg-tool<\/em> is being applied for the calculation.<\/p>\n This method is often allowed as a simplified calculation option. Like in the German ENVE calculations. The calculation with HTflux is very easy as only the automatic PSI-tool<\/em> is required.<\/p>\n Apart from the ISO calculation this method is also used by some passive house designers. The calculation with HTflux is very easy as only the automatic PSI-tool<\/em> is required for this purpose.<\/p>\n","protected":false},"excerpt":{"rendered":" \u03a8g – ground contact calculations The following pages will show you how to calculate the so called \u03a8g values. These linear thermal transmittances values are used to precisely calculate to energy loss to the ground. As always the calculation of the \u03a8 value is necessary to turn the simplified (surface based) U-value calculation of the […]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":423,"menu_order":0,"comment_status":"open","ping_status":"open","template":"pageTemp-userGuide_NEW.php","meta":{"footnotes":""},"class_list":["post-1199","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/pages\/1199","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/comments?post=1199"}],"version-history":[{"count":15,"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/pages\/1199\/revisions"}],"predecessor-version":[{"id":1277,"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/pages\/1199\/revisions\/1277"}],"up":[{"embeddable":true,"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/pages\/423"}],"wp:attachment":[{"href":"https:\/\/www.htflux.com\/en\/wp-json\/wp\/v2\/media?parent=1199"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\u03a8g-calculation with slab on or near the grade level according to ISO 10211 – Option B<\/h3>\n
\u03a8g-calculation with slab below grade level (or heated basement) using ISO 10211 and ISO 13370<\/a><\/h3>\n
\u03a8g-calculation using boundary conditions as ground (ENEV)<\/h3>\n
\u03a8g-calculation using a soil block and boundary condition as ground<\/h3>\n