ASHRAE 4768-2005 Development of the Rsidential Load Factor Method for Heating and Cooling Load Calculations (RP-1199)《用于取暖和空调负荷计算RP-1199住宅负荷因子法的发展》.pdf
《ASHRAE 4768-2005 Development of the Rsidential Load Factor Method for Heating and Cooling Load Calculations (RP-1199)《用于取暖和空调负荷计算RP-1199住宅负荷因子法的发展》.pdf》由会员分享,可在线阅读,更多相关《ASHRAE 4768-2005 Development of the Rsidential Load Factor Method for Heating and Cooling Load Calculations (RP-1199)《用于取暖和空调负荷计算RP-1199住宅负荷因子法的发展》.pdf(17页珍藏版)》请在麦多课文档分享上搜索。
1、4768 (RP-1199) Development of the Residential Load Factor Method for Heating and Cooling Load Calculations Charles S. Barnaby Member ASHRAE ABSTRACT The recent ASHRAE project, “Updating the ASHRAEI ACCA Residential Heating and Cooling Load Calculation Procedures and Data” (RP-I 199), developed two n
2、ew resi- dential loads calculation procedures: residential heat balance (RHB), a detailed heat balance method that requires computer implementation, and residential load factor (RLF), a simpli- fed procedure that is hand tractable and suitable for spread- sheet implementation. This paper describes R
3、LF and its development. The form of RLF resembles prior methods. Howevel; the sensible cooling load procedure was derived using linear regression to jnd relationships between design conditions, building characteristics, and peak cooling load predicted by RHB. This eliminated the needfor semi-empiric
4、al adjustments, such as averaging, that have been used in the development of other methods. Results comparing RLF to RHB are presented. The RLF heating load calculation is also described; it uses the traditional UAAT formulation except for improvements to procedures for infiltration leakage rate and
5、 ground (slab and basement) losses. INTRODUCTION The research project, “Updating the ASHRAE/ACCA Residential Heating and Cooling Load Calculation Proce- dures and Data” (RF-1199), had two primary products. First, a new fundamental residential heating and cooling load calcu- lation method was develop
6、ed and tested. This procedure, called the residential heat balance (RHB) method, is based on heat balance first principles as described by Pedersen et al. (1997, 1998) and ASHRAE (2001). RHB is documented by Barnaby et al. (2005). It uses a computationally intensive 24- hour design-day simulation th
7、at is practical only when imple- Jeffrey D. Spitler, PhD, PE Fellow ASHRAE mented in software. Because of its fundamental approach, RHB can be applied with few restrictions to arbitrarily complex residential buildings, including those with large fenestration areas, novel construction features, or ha
8、ving non- summer peaks. The ResHB computer program, developed as part of RP- 1 199, implements the RHB method as described in Barnaby et al. (2004). ResHB is a batch-driven FORTRAN-90 applica- tion derived from the ASHRAE Loads Toolkit (Pedersen et al. 2001) that operates on Windows-based PCs. Sever
9、al key ResHB features are noted here. First, ResHB models room temperature swing: in addition to the standard fixed-setpoint capability, ResHB can find the sensible cooling extraction rate that results in a specified temperature swing above the ther- mostat setpoint. Second, ResHB incorporates the u
10、pdated models identified in W- 1 199 as appropriate for residential loads calculation. Third, ResHB is multi-room and multi- zone, allowing application to real buildings as well as simple test cases. Finally, ResHB can model typical residential master-slave control, where a thermostat in one room co
11、ntrols the cooling delivery in another, with resulting imperfect temperature control in the slave room. The second product of RP- 1 199 is a simpler procedure, designated “residential load factor” (RLF) method. RLF is tractable by hand or can be straightforwardly implemented using spreadsheet softwa
12、re. This simplification is achieved at the expense of generality-RLF is applicable only to conven- tionally constructed residences with typical space-condition- ing requirements. The procedures and data required to use RLF are presented in the “Residential Heating and Cooling Loads Calculation” chap
13、ter of the 2005 ASHRAE Handbook- Fundamentals (ASHRAE 2005). Charles S. Barnaby is vice president of research at Wnghtsoft Corporation, Lexington, Mass. Jeffrey D. Spitler is CM Leonard Professor in the School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, Okla. o200
14、5 ASHRAE. 291 This paper discusses the design of RLF and documents the methodology used in its development. Some testing results are also presented. While RLF includes both cooling and heat- ing load procedures, the heating calculations rely on the tradi- tional UAAT model that has proven satisfacto
15、ry for decades. Improvements have been introduced in relation infiltration leakage rate and to ground heat loss. The RLF cooling procedure resembles and builds upon prior methods but was developed using a linear regression approach that avoids some semi-empirical derivations used in the past. Prior
16、methods have been published by the Air-Condi- tioning Contractors of America (ACCA), including the widely used Manual J, seventh edition (ACCA 1986) and Manual J, eighth edition (ACCA 2003). The 1989-2001 editions of the ASHRAE Handbook-Fundamentals included a method based on 342-RP (McQuiston 1984)
17、. Canadian Standard CAN/CSA-F280-M90 (HRAI 1996; CSA 1990) specifies a cooling method also based on 342-RI and a heating procedure that includes enhanced ground loss calculations. RLF COOLING LOAD CALCULATION The RLF cooling load calculation is based on the idea of independent load components, as ar
18、e prior simplified meth- ods. The load contributions from various sources are sepa- rately evaluated and then summed. The following sections summarize the method, showing both sensible and latent components as applicable. Later sections document the deri- vation of the component models and coefficie
19、nts. In FUF, surfaces have associated load factors (LFs) or load contribution per unit area. These are designated CFs for cooling and HFs for heating. For the most part, HF values are simply UAT CF values depend on surface construction, climate, and, in some cases, surface orientation, solar absorp-
20、 tance, or other characteristics. Each unique LF needs to be evaluated once for a given set of site and construction condi- tions and then is applied repeatedly to building elements of the same type. This two-step process is convenient for hand or spreadsheet application. Note that LFs are the funct
21、ional equivalent of ManuaZSs heat transfer multipliers (HTMs) but are derived differently and in general do not have the same values. Surface Type Ceiling or knee wall adjacent to vented attic Ceilinghoof assembly Wall Floor over ambient Floor over crawlspace Total Cooling Load 9, = CAj. CF, + qvj,
22、+ qig,s 41 = 4ViJ + 9igJ where qs = sensible cooling load, W (BtUni) q1 = latent cooling load, W (Btuni) Ai = area of ith surface, m2 ( l/(Rcvr+ 0.12) W/m2.K or 1/(Rc, + 0.68) BtUni.F 292 ASHRAE Transactions: Research Table 2. Fenestration Coefficients Exposure N NE FFs 0.17 0.09 E I 0.17 I SE S 0.2
23、5 0.45 I sw I 0.54 I W NW 0.48 0.34 I Horiz I 0.66 I Fenestration Fenestration cooling factors are calculated as follows: CFyen = U.(AT-0.49.DR)+FFs.PXI.SHGC.IAC (5) where CFfen = u= DR = AT = FF, = PXI = SHGC = ZAC = Peak fenestration cooling factor, W/m2 (tih.) fenestration NFRC heating U-factor,
24、W/m2.K daily range of outdoor dry-bulb temperature, K (“F) cooling design temperature difference, K (OF) load factor (see Table 2) peak exterior irradiance, including shading modifications (see below), W/m2 (StUih.ft2) fenestration rated or estimated NFRC solar heat gain coefficient interior shading
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