<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV><BR class="khtml-block-placeholder"></DIV><DIV>A recent question about flow networks without an external (boundary) node.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" size="4"><SPAN class="Apple-style-span" style="font-size: 14px;">I am trying to use ESP-r to simulate the performance of a room with vented trombe wall,and i creat the air flow network without external environment node seeing the figure attachment,but i doubt whether it works right.</SPAN></FONT></DIV></BLOCKQUOTE><BR><DIV>It is guaranteed that this will not work. According to the documentation</DIV><DIV>all flow networks much include at least one boundary node type (either</DIV><DIV>to a wind pressure node or a specified pressure node). ESP-r probably</DIV><DIV>complained a lot about this model. Air</DIV><DIV>is not compressible in the flow solution so there must be some</DIV><DIV>connection (even if it is via several other paths) from every internal </DIV><DIV>node to a boundary.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>And in reality few buildings are 100% closed (might happen in the</DIV><DIV>International Space Station). There are several of the</DIV><DIV>exemplar models which illustrate options for creating links to the</DIV><DIV>outside.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>And those who would like to find out more about designing flow networks</DIV><DIV>have a look at the ESRU web page for upcoming training events.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>-ESRU</DIV></BODY></HTML>