Hot, Humid, and Still Cool?

Transcription

1 7 th th Annual North American Passive House Conference September Denver, Colorado Hot, Humid, and Still Cool? Corey Saft, Saft Architecture Eric Helton, Bloomfield Research Labs LLC

2 7 th th Annual North American Passive House Conference September Denver, Colorado Session Learning Objectives: Unique challenges of designing a Passive House for the Hot/Humid climate Monitoring and experiential data from the first 18 months of a Passive House in the Hot/Humid climate zone Latent load issues in ventilation air in humid climates Demands for human comfort in the deep South of the U.S.

3 TEAM Design & Development Corey Saft, Saft Architecture PHPP Consultant Katrin Klingenberg, Executive Director, PHIUS Data Analysis Eric Helton, Bloomfield Research Labs LLC Special Acknowledgement: Latent load / ERV discussions & invaluable guidance throughout the entire project Z Smith, Eskew+Dumez+Ripple

4 Lafayette, Louisiana

5 Lafayette, Louisiana

6 Lafayette, Louisiana

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8 ENVELOPE

9 SYSTEMS

10 SYSTEMS

11 SYSTEMS Calculated Energy Values for the Saft Residence. Heating Demand, kwh/m²yr, (kbtu/ft²/yr) 10 (3.17) Peak Heat Load, W/ m², (Btu/h/ft²) 18 (5. 7) Cooling Demand, kwh/m²yr, (kbtu/ft²/yr) 15 (4.75) Peak Cooling Load, W/ m², (Btu/h/ft²) 14 (4.44) Specific Primary Energy Demand, (37.03) kwh/m²yr, (kbtu/ft²/yr) Airtightness = pascal pressure U-value R-value SHGC VT picture casement/awning Dual Pane, 1 Low SHG Film Krypton exterior walls - R-28 1 HCFC free Polyiso Rigid board 5.5 open cell insulation -castor-based spray foam insulation -100% water-blown, free from HFCs and PBDEs roof R-55 2 HCFC free Polyiso Rigid board 11 open cell insulation -castor-based spray foam insulation -100% water-blown, free from HFCs and PBDEs crawl space walls R-21 4 XPS crawl space slab R XPS

12 lafayette, la

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15 CLIMATE Climate & PH

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17 CLIMATE

18 LATENT LOAD humidity after H. Gifford

19 LATENT LOAD humidity Air with dewpoint> 62 F will have RH > 60% at 78 F (must dehumidify to stay in ASHRAE comfort zone) after H. Gifford

20 LATENT LOAD

21 US COMPARISONS

22 LATENT LOAD

23 DATA COLLECTION DataLogging

24 DATA COLLECTION: Temperature and Humidity U12 Series Loggers: Used in Critical Locations Temperature Stated Accuracy: ±0.63 F Uniformity Test: ±0.2 F Relative Humidity Stated Accuracy: ±2.5 %RH Uniformity Test: ±1 %RH H08 Series Loggers: Used in Peripheral Locations Temperature Stated Accuracy: ±1.5 F Uniformity Test: ±1.5 F Relative Humidity Stated Accuracy: ±5 %RH Uniformity Test: ±2 %RH Note: Because the loggers were of a variety of ages, uniformity tests were done to verify functionality. Measurement accuracy remains the manufacturer s stated accuracy.

25 DATA COLLECTION: Electrical Energy 4-Channel TED-5000 Stated Accuracy: 2% Comparison to rolling 12-months of utility bills: ±2% Three Active Measurements Net Exchange with Grid PV Generation Mini-Split Heat Pump

26 DATA COLLECTION: Installation Locations DataLogging

27 DATA COLLECTION: Installation

28 ENERGY Monthly total electrical energy use and generation

29 ENERGY & COMFORT

30 COMFORT: Temperature and Humidity Monthly Avera age Temperature [F] Feb Apr Jun Aug Oct Outdoor Outdoor, Min or Max (dashed) Living Room Loft (Thermostat Location) Kitchen/Living Room Bedroom 1 Bedroom 2 Bedroom 3 Crawlspace Indoors, Min or Max (dashed) Dec Feb Apr Jun Aug Monthly Average Relative Humidity [%RH] Feb Apr Outdoor Outdoor, Min or Max (Dashed) Living Room Loft Kitchen/Living Room Bedroom 1 Jun Aug Oct Dec Feb Bedroom 2 Bedroom 3 Crawlspace Indoors, Min or Max (Dashed) Apr Jun Aug

31 COMFORT: Dew Point Temperature Monthly Average De ewpoint Temperature [F] Outdoor Outdoor, Min or Max (Dashed) Living Room Loft (Thermostat Location) Kitchen/Living Room Bedroom 1 Bedroom 2 Bedroom 3 Crawlspace Indoors, Min or Max (Dashed) Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

32 ENERGY

33 ENERGY PHPP modeling and 12-month measured energy data

34 CONCLUSIONS Heating was rarely required, and the actual use was about 7% of the PHPP predicted need. Cooling was more significant, but still only 70% of the predicted need. Primary energy was approximately 50% greater than predicted by the PHPP. Annual latent is estimated to be 15 kwh/m2/yr ( to no quota).

35 ENERGY

36 FACTORS RELATIVE TO THE LARGER THAN EXPECTED PRIMARY ENERGY: The addition of the stand alone dehumidifier in August While the ERV is critical to performance, the measured performance (35%) is less than rated and suffered a few operational issues over the course of the study such as an extended period with an increasingly blocked intake duct The occupants maintained a large electronics collection, including computers, video games, stereo equipment, an extra mini-fridge, projector and amplified musical instruments. The house is a rental / irregular/inconsistent student lifestyle

37 Monthly Average Dewpoint Temperature [F] Outdoor Outdoor, Min or Max (Dashed) Living Room Loft (Thermostat Location) Kitchen/Living Room Bedroom 1 Bedroom 2 Bedroom 3 Crawlspace Indoors, Min or Max (Dashed) Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Monthly Total Energy [kwh] House, Net House, Total Minisplit PV Generation Feb Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

38 CONCLUSIONS The house exceeded the primary energy modeling by the PHPP for 12 months of data The 12-month measured heating and cooling energy totals were below the PHPH model Comfort marginally maintained during the summer, but temperature uniformity between the open and private spaces was impossible The PHPP model did not realistically model the high cumulative latent loads induced by ventilation air in the hot/humid climate The HERS model was very accurate

39 CONCLUSIONS Point source heating/cooling is problematic A convective based strategy for distribution is problematic Latent load is problematic

40 FUTURE WORK The next major modification to the data collection project will be a dedicated monitoring of the dehumidifier energy consumption separately from the ERV and the mini-split Re-evaluate dehumidifier / ERV / minisplit sequencing Work with the PHIUS/PHPP software team to ensure latent loads are handled realistically More flexible and realistic energy requirements by setting a Total Source Energy and allowing each building to adapt this total, as appropriate for the climate, to heating/cooling/dehumidification

41 FUTURE WORK Every building is a forecast. Every forecast is wrong. - Futurist Stewart Brand quoted in NRELs Getting to Net Zero

42 Acknowledgements Monitoring Funding: PHIUS University of Louisiana at Lafayette Latent Load and ERV Discussions as well as invaluable guidance throughout the entire project: Z Smith, AIA, LEED AP BD+C, Director of Sustainability & Building Performance, Eskew+Dumez+Ripple, New Orleans, LA Data Collection: Hunter Duplantier Justin Aurbert Liran Timiansky

43 References

44 Corey Saft Eric Helton