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<span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><div><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">Hi,</span></div></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">I am looking for some feedback on thermal mass optimization for passive solar in </span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 16px; ">DesignBuilder/ EnergyPlus.</span><div><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">I attempted a basic sensitivity analysis for thermal mass optimization for a very basic passive solar design (one south facing window, lots of insulation, all assemblies with interior concrete thermal mass). I modelled this concept using DesignBuilder with various concrete thicknesses (5cm to 50cm) but keeping the envelope U value, and all other parameters constant. I used the CTF algorithm. The annual simulation results indicate that increasing thermal mass past 20cm continues to decrease heating energy consumption, in a somewhat linear fashion. Even more unusual, was that the savings from going with 30cm compared to 20, was much greater than that achieved by the change from 10cm to 20cm. </span><div><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span></div><div><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">This does not match with the literature I have read, which suggest that this relationship should be a negative exponential decay (continuous diminishing energy savings with each added thickness). Many guidelines suggest that savings plateau at 20cm of thermal mass (as concrete).</span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">Is this a problem with EnergyPlus? Or DesignBuilder? Any suggestions?</span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">Thanks for your time,</span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">Hayes Zirnhelt</span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">M.A.Sc Candidate, RU Building Science</span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; "><br></span><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12pt; ">B.A.Sc Integrated Engineering</span><br><br></div></div> </body>
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