A 2015 whole-building simulation study by Schnieders, Feist and Rongen demonstrated that the Passive House (Passivhaus) functional criterion — meeting all heating, cooling and dehumidification needs of a dwelling through the hygienic supply-air stream alone — can in principle be satisfied in climates from Yekaterinburg to Singapore, but concluded that several technical issues remain unresolved for robust practical deployment: (i) no ventilation unit combining high-efficiency heat recovery with effective humidity transfer while preserving frost protection was commercially available for very cold climates; (ii) matching the independent sensible and latent loads of hot-humid climates forces the supply-air cooling coil to very low temperatures (about 3 °C), with condensation, mist and cold-discomfort risks whose practical engineering solutions were not yet developed; (iii) strategies for decoupling sensible cooling and dehumidification in a compact fresh-air unit (e.g. wrap-around heat pipes, internal heat-recovery loops) had been identified but neither optimized nor field-tested across realistic internal-load scenarios; and (iv) cost-effective, moisture-safe basement construction for warm-humid climates (where unconditioned basements can exceed 80% relative humidity for months) remained an open question. Later work has brought partial progress — membrane enthalpy exchangers are now on the market and monitored passive houses exist in hot and subtropical climates — but no resolution: membrane enthalpy exchangers are experimentally shown (2023) to frost below −14 °C with severe effectiveness loss near −26 °C, a 2022 review concludes that available frost-control strategies degrade indoor air quality or raise energy use, and no work develops or field-tests the low-temperature supply-air engineering or moisture-safe basements. The problem — achieving robust, field-validated building-services solutions for these four linked climate-transfer barriers — remains open.

Background

The Passive House (Passivhaus) is a performance-based building energy standard, developed and first validated in central Europe, whose defining functional requirement is that a dwelling's entire space-conditioning need — heating, cooling and dehumidification — can be met by the hygienic outdoor-air supply stream alone (roughly 0.3–0.4 air changes per hour), which is only possible if the peak heating or sensible cooling load is held below about 10 W per m² of treated floor area. This is achieved through a highly insulated, airtight envelope and mechanical ventilation with heat recovery (MVHR): a ventilation unit in which exhaust air pre-conditions the incoming fresh air through an air-to-air heat exchanger, typically a counter- or cross-flow plate exchanger or a rotary wheel. In very cold climates, the exhaust-side surface of such exchangers can drop below the frost point, so that condensed water freezes and progressively blocks the exchanger; frost protection (preheating the supply air, periodic defrost cycles or bypassing the exchanger) trades away recovery efficiency, indoor air quality or energy. A heat exchanger that also transfers water vapour — an enthalpy or total-energy exchanger, realized either as a rotary wheel coated with a desiccant or as a plate exchanger whose plates are gas-permeable membranes — recovers latent as well as sensible heat and raises the supply-air dew point, which in principle both alleviates winter dryness and reduces frost formation; its moisture-transfer performance and cold-climate behaviour are active research topics. In cooling-dominated climates the building's heat load splits into a sensible part (lowering air temperature) and a latent part (removing moisture, the dominant load in humid climates); a conventional cooling coil dehumidifies by cooling air below its dew point, so independently matching the two loads within a single compact fresh-air duct can force very low supply-air temperatures, with risks of condensate on ductwork, mist at outlets and local cold drafts. Wrap-around heat pipes — passive two-phase devices that pre-cool air before the coil and reheat it after it, using the same heat — are one known means of decoupling sensible and latent removal without extra energy, but their integration in compact residential fresh-air units had not been optimized or field-tested. Against this background, Schnieders, Feist and Rongen (2015) used validated hygrothermal dynamic simulation (DYNBIL, the Passive House Institute's dynamic whole-building heat- and moisture-balance simulation tool) of a reference two-storey house in six climates (Yekaterinburg, Tokyo, Shanghai, Las Vegas, Abu Dhabi, Singapore) to show that the Passive House criterion is physically achievable in each, with 75–96% reductions in annual conditioning energy relative to a traditionally insulated reference — and simultaneously identified, in their conclusions, the four unresolved technical barriers to robust practical deployment listed in the problem statement, which concern the building-services equipment (ventilation units, supply-air cooling and dehumidification, and below-grade construction) rather than the envelope itself.

Problem Statement

The problem, as posed by the conclusions of Schnieders, Feist and Rongen (2015), is to close the four linked technical barriers that stand between the demonstrated in-principle feasibility of Passive Houses in extreme climates and their robust practical deployment — all in service of one objective: a dwelling whose heating, cooling and dehumidification needs are met solely by the hygienic supply-air stream, realized with reliable, field-validated, cost-effective building-services components. Specifically: (i) for very cold climates such as Yekaterinburg, to develop a ventilation unit that achieves simultaneous high-efficiency heat recovery and effective humidity transfer — combining a moisture-transferring heat-recovery device of any kind, e.g. a desiccant-coated rotary wheel or a membrane plate heat exchanger — without degrading frost protection at the low outdoor temperatures such climates impose; (ii) for hot-humid climates, to develop practical engineering solutions for the low-temperature supply-air distribution that results when the cooling coil must independently match the building's sensible and latent loads — air supplied at temperatures of roughly 3 °C, with its attendant risks of condensate formation on ductwork, mist at the outlets, and local cold discomfort; (iii) to optimize and field-test, across the range of internal load scenarios encountered in real dwellings, a strategy for decoupling sensible cooling and dehumidification within a compact fresh-air unit — for example controllable wrap-around heat pipes or internal heat-recovery loops, among other passive decoupling means — whose principle was identified but left unvalidated in 2015; and (iv) to establish cost-effective, moisture-safe basement construction methods for Passive Houses in warm-humid climates, where unconditioned basements can otherwise remain above 80% relative humidity for months and pose a serious mould risk. Closing these barriers requires a concrete engineering solution shown to meet the Passive House functional criteria defined in the Background, without the penalties the 2015 review identified as blocking robust deployment: degraded indoor-air quality, added energy use beyond those criteria, condensation and comfort faults (condensate on ductwork, mist at the outlets, or local cold discomfort), or a cost penalty that outweighs the demonstrated performance gain.

References

  1. Jürgen Schnieders, Wolfgang Feist, Ludwig Rongen. Passive Houses for different climate zones. Energy and Buildings 105 (2015) 71–87. DOI: 10.1016/j.enbuild.2015.07.032. https://doi.org/10.1016/j.enbuild.2015.07.032
  2. Jürgen Schnieders, Tim Delhey Eian, Marco Filippi, Javier Florez, Berthold Kaufmann, Stefanos Pallantzas, Monte Paulsen, Elena Reyes, Micheel Wassouf, Shih-Chieh Yeh. Design and realisation of the Passive House concept in different climate zones. Energy Efficiency 13(8) (2019) 1561–1604. DOI: 10.1007/s12053-019-09819-6. https://doi.org/10.1007/s12053-019-09819-6
  3. H. Y. Bai, P. Liu, M. Justo Alonso, H. M. Mathisen. A review of heat recovery technologies and their frost control for residential building ventilation in cold climate regions. Renewable and Sustainable Energy Reviews 162 (2022) 112417. DOI: 10.1016/j.rser.2022.112417. https://doi.org/10.1016/j.rser.2022.112417
  4. Hao Li, Tao Zhang, Ji Zhang, Bowen Guan, Xiaohua Liu, Takema Nakazawa, Lin Fang, Toshio Tanaka. Investigation of energy recovery performance and frost risk of membrane enthalpy exchanger applied in cold climates. Energy 282 (2023) 128894. DOI: 10.1016/j.energy.2023.128894. https://doi.org/10.1016/j.energy.2023.128894
  5. Dietmar Siegele, Fabian Ochs. Effectiveness of a membrane enthalpy heat exchanger. Applied Thermal Engineering 160 (2019) 114005. DOI: 10.1016/j.applthermaleng.2019.114005. https://doi.org/10.1016/j.applthermaleng.2019.114005
  6. Aleksejs Prozuments, Jurgis Zemitis, Aleksejs Bulanovs. Cold Climate Challenges: Analysis of Heat Recovery Efficiency in Ventilation Systems. Energies 16(22) (2023) 7483. DOI: 10.3390/en16227483. https://doi.org/10.3390/en16227483
  7. May Khalfan, Steve Sharples. The Present and Future Energy Performance of the First Passivhaus Project in the Gulf Region. Sustainability 8(2) (2016) 139. DOI: 10.3390/su8020139. https://doi.org/10.3390/su8020139
  8. Paris A. Fokaides, Elias Christoforou, Milos Ilic, Agis M. Papadopoulos. Performance of a Passive House under subtropical climatic conditions. Energy and Buildings 133 (2016) 14–31. DOI: 10.1016/j.enbuild.2016.09.060. https://doi.org/10.1016/j.enbuild.2016.09.060
  9. Roy Candra Sigalingging, David Chow, Steve Sharples. Applying the Passivhaus standard to a terraced house in a hot and humid tropical climate – Evaluation of comfort and energy performance. Building Services Engineering Research and Technology 41(3) (2020) 247–260. DOI: 10.1177/0143624420912511. https://doi.org/10.1177/0143624420912511
  10. May Zune, Renata Tubelo, Lucélia Rodrigues, Mark Gillott. Improving building thermal performance through an integration of Passivhaus envelope and shading in a tropical climate. Energy and Buildings 253 (2021) 111521. DOI: 10.1016/j.enbuild.2021.111521. https://doi.org/10.1016/j.enbuild.2021.111521
  11. Alejandro Moreno-Rangel, Tim Sharpe, Gráinne McGill, Filbert Musau. Indoor Air Quality in Passivhaus Dwellings: A Literature Review. International Journal of Environmental Research and Public Health 17(13) (2020) 4749. DOI: 10.3390/ijerph17134749. https://doi.org/10.3390/ijerph17134749
  12. Vishwajit Anand, Vishnu Lakshmi Kadiri, Chandrasekhar Putcha. Passive buildings: a state-of-the-art review. Journal of Infrastructure Preservation and Resilience 4(1) (2023) 3. DOI: 10.1186/s43065-022-00068-z. https://doi.org/10.1186/s43065-022-00068-z