Joe Huang对DOE2认识误区的澄清

作者：Joe huang，美国白盒子技术公司主席，Ashrae能耗计算分会主席。曾经是LBNL（劳伦斯伯克利实验室）的科学家，参与DOE2和EnergyPlus开发。

Nowthat I've got some time, I've decided to write a little about why I thought thecomparative descriptions of EnergyPlusand DOE-2 qouted in Arpan's post wereincomplete and biased against eQUEST/DOE-2.I'll go through these in the order mentioned in Arpan’s post:

既然我有了些时间，我决定一些东西关于我为什么认为Arpan发布的文章中所引用的EnergyPlus和DOE2的对比是不完整的并且对DOE2/eQUEST带有偏见。我按照Arpan发布的文章中的顺序做逐一回复。

1. HVAC Loads

1.空调负荷

Theways that EnergyPlus and DOE-2 calculate conduction loads areactually not that different. Both use Conduction Transfer Functions (CTFs in EnergyPlus, not DOE-2) or Response Factors (RFs in DOE-2) to calculate heat flows and thermal storage in the surfaces.CTFs and RFs are different formulations of the same technique whereby thethermal response of a surface to a given input (pulse of temperature for RF orheat for CTFs) is solved once for a linearized time series that is then scaledto the actual inputs to get the thermal response of the layer during each timestep. This is a well-established technique first applied to building energycalculations by Mitalas and Stephenson in the late 1970's and without whichprograms like DOE-2, BLAST, etc., could not have beenwritten.

EnergyPlus和DOE-2计算导热负荷实际上差异没有那么大。两者分别使用导热传递函数（CTFs）和响应因子(RFs)来计算表面的热流密度和蓄热。CTFs和RFs是相同技术的不同提法，都是通过一次性求解线性时间序列中给定输入（温度脉冲波（RF），热流脉冲波（CTFs））下的围护结构表面的热响应。然后，将给定的输入缩放成实际输入，从而获得此此实际输入下的每个时间步长的热响应。这是一个完善的技术。在20世纪70年代，首次被Mitalas和Stephenson应用于建筑能耗计算，没有这个技术，DOE-2，BLAST等程序不可能编制。

Solvingthe space loads is where there's a difference between DOE-2 and EnergyPlus. Thecommon description of this difference is thatDOE-2 uses Weighting Factors (WF) whereas EnergyPlus uses Heat Balance, which actually confuses more thanexplains the actual difference. WFs are the same computational technique as theRF/CTF applied to a zone rather than a surface. DOE-2 does a Heat Balance calculation once to derive a WF that isthen used in the simulation, whereas EnergyPlusdoes a Heat Balance calculation at every time step.

空间负荷的求解是DOE2和EnergyPlus的不同之处。一般的关于这个不同的说法是DOE使用权重因子法而EnergyPlus使用热平衡法，实际上，这种说法与其说它解释了DOE和EnergyPlus的不同之处，还不如说他更容易让人困惑。权重因子法是一种和RF/CTF相同的计算技术，只不过他应用于空间而不是围护结构表面。DOE2使用了一次热平衡计算推导出权重因子，然后将此权重因子用于后来的负荷模拟，但是EnergyPlus在每个时间步长都使用了热平衡计算。

Thesavings in computation are clearly significant, but the question is how much doWFs vary over time? Leaving aside very unusual buildings with moving or dynamicsurfaces, e.g., movable night insulation over greenhouses, a building'sphysical condition is static, so the only reason that WFs would change is when alarge increase in air flow which would change the interior air filmcoefficents, i.e., with high ventilation. More than 20

years ago, I did a study concluding that "inside airtemperatures and cooling loads are insensitive to the choice of insideconvective air film conductance for air change rates between 0 and 30ACH". (Huang and Winkelman 1993. "Sensitivity of Calculated BuildingLoads and Temperatures to Variations in Convective Air Film Conductance",report to CIEE).

DOE2空间负荷的计算方法在计算代价的节省是很明显的，但是问题是权重因子究竟随时间变化有多大？

除了非常特殊使用了动态围护结构的建筑之外，例如，使用了可变的夜间保温的温室，一个建筑的建筑物理状态是静态的，那么唯一影响权重因子的是建筑内气流增加很大导致内部空气对流换热系数变化，例如，高通风。大约20年前，我做了一个研究得出结论“在0-30的换气次数下，室内温度和冷负荷对空气对流换热系数不敏感” (Huang and Winkelman 1993."Sensitivity of Calculated Building Loads and Temperatures to Variationsin Convective Air Film Conductance", report to CIEE).

Ofcourse, one would always like to see techniques improved and it's been pointedout by other experts that it's not difficult to recalculate WFs "on thefly” as need, if that were to produce significant improvement in accuracy. Sofar, I haven't seen much evidence of this need and all the statements thatdoing a Heat Balance at every time step is "more accurate" have beenargued purely on theoretical grounds.

当然，人们通常想看看技术的改善，并且也有其他专家提出，每个时间步长重新计算权重因子也并不难，如果这样做在精度方面有很大改善的话。到目前为止，我还没有看到这方面需要的大量证据，并且所有 每一个时间步长做热平衡计算更精确的说法都是纯粹以理论层面为依据。

Theclaim in Arpan's post that DOE-2cannot handle thermal mass is something I've been hearing since the early1980's, but which has never been demonstrated. In 1982, when DOE asked LBNL tolook into the energy performance of masonry buildings, we even hired aresearcher to compare DOE-2 to BLAST (the precursor to EnergyPlus) for high

mass buildings, whoconcluded that the results were essentially the same (Huang et al., 1989.“Affordable Housing Through Energy Conservation”, DOE/SF/00098-H3, alsoLBL-19128)

Arpan发表的文章中关于DOE2不能处理蓄热的断言，早在20世纪80年代就有人提起，但是并没有得到证实。在19xx年，DOE让LBNL调查砖石结构建筑的能耗性能，我们甚至雇佣了一个研究者比较DOE-2和BLAST（EnergyPlus前身）用于高蓄热建筑差异，他得出结论结果基本相同。（Huang et al., 1989. “Affordable HousingThrough Energy Conservation”, DOE/SF/00098-H3, also LBL-19128）

2. IntegratedSimulation of Loads and Systems

2.负荷和系统的整合模拟

Theclaim is that EnergyPlus calculatesthe building response simultaneously with system operation, whereas DOE-2 does not. This is anothermisconception, possibly due to not fully understanding how either programreally work.

按照Arpan声称的，EnergyPlus计算建筑响应的同时进行系统模拟，但是DOE2没有。这又是一个概念的误解，原因是没有完全理解两个程序事实上是如何运作的。

Althoughthe ideal solution would be to solve the loads and system outputsimultaneously, in truth both EnergyPlusand DOE-2 calculate themsequentially. The difference is that DOE-2does Loads for the entire run period, and then repeats with System, whereas EnergyPlusdoes them sequentially ateach time step.

虽然理想的求解方式是同时求解系统和负荷输出，但是实际上EnergyPlus和DOE2都是串行计算。差异是DOE2实在整个运行时段，先做负荷计算，然后做系统计算。但是EnergyPlus是在每个时间步长内做串行计算。

DuringSystems, DOE-2 simultaneously solvefor the System Load, temperature, and system output. In fact, the TEMDEVroutine that does this is perhaps the most valuable contribution that DOE-2 has made to building energysimulations. Therefore, I do not agree with the statement that “DOE-2 has limited feedback from HVACsystem operation on building loads”.

在做系统计算过程中，DOE-2同时求解系统负荷，温度，系统输出。实际上，TEMDEV子程序这样做可能是对建筑能耗模拟最有价值的贡献。因此，我不同意DOE-2空调系统计算建筑负荷计算做了很有限的反馈的论断。

Asfar as which method is more accurate, I really can't tell and detailedmeasurements would be very helpful. The EnergyPlusLoads are clearly better than the DOE-2uncorrected Loads, but those are purely diagnostic values never meant to beused (when DOE-2 Users give theLoads, they always refer to the SystemLoads). The DOE-2 System Loads, onthe other hand, is a simultaneous solution, which theEnergyPlus Loads are not (unless there’s iteration), which may beimportant when zone temperatures change significantly over one time step, asduring morning start-up. 至于那个方法更精确，我实在讲不出来，详细的测试会有很大帮助。EnergyPlus计算的负荷比DOE2未校正的负荷肯定更好，但是这个值纯粹是用于诊断，从来没有使用（DOE2用户给出负荷时，通常是指系统负荷）。另一方面，DOE2系统负荷是系统和建筑负荷联立求解的结果，EneryPlus负荷并不是（除非使用了迭代），当室内温度在一个时间步长内变化很大时这一点非常重要，例如早晨的空调系统启动时段。

Ifrankly don't understand the basis for the statement that "DOE-2 can't accurately simulate systemsand heat transfer where zones are [underconditioned]", unless one were tostop after the Loads simulation, which nobody would ever does! I fail to see

why the TEMDEV routine wouldhave any difficulty in solving for the actual zone temperature when there is noHVAC input, in fact, it actually becomes easier! Eversince its first release, DOE-2 hasalways reported temperatures and underconditioned hours for any zone,conditioned or unconditioned.

坦白讲，我不能理解“当时空间处于空调（采暖）工况时DOE-2不能够准确模拟HVAC系统和室内热传递”，除非有人在DOE2完成负荷模拟后，终止程序运行，没有人会这样做。我没有发现TEMDEV子程序在求解无暖通空调系统情况下的实际室内温度有任何困难，在DOE2程序中，这个问题实际上变得更简单了。即使是DOE2的第一个版本，也会报告任何空间室内温度和室内处于空调（采暖）小时数，包括空调和非空调空间。

3. ThermalComfort

3.热舒适

The story here is that EnergyPlus can calculate surfacetemperatures, but not DOE-2, butthat's not the end of the story. DOE-2 does not explicitly solve forsurface temperatures, but radiant heat flows are taken care in the WFs to solvefor the zone air temperature. Therefore, it is possible to back-calculate theinside surface temperatures, and in 2000 EMPA(Switzerland) added a routine to DOE-2.1Eto do that, which I have used to calculate thermal comfort (PMV, PPD, etc.) ona project for Egypt in 2002 (both references can be provided on request).

这里言外之意是说EnergyPlus能够计算表面温度，但是DOE2不能，然而言外之意并不止这些。DOE2没有显式求解表面温度，但是辐射热流密度被在WFs（权重因子）计算过程中保留，它被用于计算室内空气温度。因此，可以反向计算内表面温度，EMPA（瑞士）在DOE2.1E中添加了一个子程序用于计算内表面温度，我已经在20xx年使用它计算了一个埃及项目的热舒适。 4. DisplacementVentilation Systems

4.置换通风系统

Itis claimed that EnergyPlus can modelthermal stratification through a 3-node stratification model, whereas DOE-2 assumes that all zones are fullymixed. It should be clarified that this 3-node stratification model is part ofthe DV model developed by UCSD, and not part ofEnergyPlus' general zone model, which also assumes uniformconditions within each zone. The same DV model could also be incorporated into DOE-2, as well.

按照Arpan声称的，EnergyPlus能够模拟热分层通过一个3节点分层模型，但是DOE2假定所有的空间内空气是充分混合。这个要澄清的是3节点分层模型是置换通风模型（DV模型）的一部分，这个DV模型是由加州大学圣迭戈分校开发的，并不是EnergyPlus常规空间模型（Zone model）的一部分，EnergyPlus的常规Zone模型也是假设每个空间室内参数是一致的。相同的DV模型也可以植入到DOE-2中。

5. UnderfloorAir Distribution Systems

5.地板送风系统

Thesame claim is made that DOE-2 assumesall zones are fully mixed, cannot model supply plenums, and thus can't handleUFAD. UFAD has been modeled in DOE-2 for upwards of 20 years, thesimplest method being to adjust the thermostat setpoint inrecognition of the vertical temperature stratification. Supply plenums have always been available in DOE-2, so I don't know where this claimcame from.

和上面相同的观点：“DOE2假定所有空间是充分混合，不能模拟送风静压箱，因此不能模拟地板送风系统。”

地板送风系统在DOE2中已经模拟了超过20年，最简单的方法是调整恒温器设置温度来等效温度分层。送风静压箱在DOE2可以模拟，所以我不知道这种说法的依据是什么。

6. RadiantCooling and Heating Systems

6.辐射制冷和制热系统

Theclaim is the DOE-2 can't modelradiant systems. My understanding is that DOE-2/eQUESTcan handle low-temperature heating or high-temperature cooling radiant systemswhere the predominant effect is to condition the air, rather than directradiant exchange between the panels and the occupants. I’m also of the impression that most radiant systems are low-temperature.

Arpan声称DOE2不能模拟辐射系统辐射系统。我的理解是DOE2/eQUEST能够处理低温供暖和高温供冷辐射系统，这些系统主要作用是通过调节空气来达到制冷和制热效果，并不是辐射板和人员直接辐射换热。我印象中最多的辐射系统是低温的。

7. NaturalVentilation

7自然通风

Themain difference between EnergyPlusand DOE-2 is that EP is coupled witha multi-zone airflow network model, whereas DOE-2uses the single-zone Sherman-Grimsrud model. Both models are scientificallybased, with bouyancy and wind-driven airflows. Since DOE-2.1E, the SG model is available to all System Types that havean Air system. The main limitation is that DOE-2cannot model interzone air flow from room to room or floor to floor. As withthe previous three system types, there is nothing intrinsic in the DOE-2 code that prohibits hooking up toa multi-zone airflow network model, and at one point in the late1990’s there was discussion of hooking up COMIS withDOE-2.1E, but that was abandoned with DOE’s decision to supportonly EnergyPlus.

EnergyPlus和DOE2主要的差异是EnergyPlus耦合了一个多区域气流网络模型，但是DOE2使用单个区域Sherman-Grimsrud模型。两个模型都是科学合理的，都考虑了浮力和风压形成气流。DOE2.1E中，SG模型在所有带有风系统的空调系统都是可用的。主要的限制是DOE2不能模拟区域间的气流流动。正如前面提到的三种系统（置换通风，地板送风，自然通风），在DOE-2代码中 没有什么实质的内容禁止其与一个多区域网络模型挂接。 在20世纪90年代后期，曾今一度讨论把COMIS和DOE2.1E连接，但是这个提议被DOE放弃，为了专门开发EnergyPlus。

8. Cogeneration

8.联产技术

Ihaven't followed this much, so can't comment.

对此不熟悉，不做评论

9. Windowsand Shading Controls

9.窗户和遮阳控制

Thisis another one of those "out of the blue" comments. Is there noawareness of DOE-2 User Functions,which have been around since the mid-1980's. DOE-2 User Functions allow expert users to add routines to the codebeyond what's allowed by the BDL input language. I've done work over the past 5years for the Window Film (IWFA) and Window Shading (PAMA)industries to model various window shading strategies and even modify windowproperties.

这是另外一个令人沮丧的评论。不了解DOE2用户输入函数（DOE-2User Function），DOE2输入函数允许专家用户添加子程序到代码中，可以超越BDL输入语言的限制。我在过去5年，我工作于窗户玻璃贴膜和窗户遮阳产业，模拟不同的遮阳策略甚至修改窗户属性。

Overthe years, I've also seen a professor in New Mexico create 20 differentconfigurations of evaporative cooling systems, CANMET (Canada) create

adessicant cooling system model, and CABR (China) a fan-coil system withconditioned Outside Air system common to China, all using DOE-2 User Functions.

? 多年来，我看见新墨西哥州的一个教授创建了20种不同的蒸发式制冷系统，CANMET（加拿大）

创建了除湿制冷系统模型，和CABR（中国）创建了一个中国常用的风机盘管加独立新风模型，这些都使用了DOE2输入函数。

翻译：赵永青

20xx年8月5日