Strengthening the Core

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With PHIUS+2018 we took a clear step forward in our commitment to being on the frontline of promoting sustainable energy use in buildings and reducing carbon emissions.

But passive building stakeholders have raised some valid concerns about PHIUS+ 2018 that deserve to be addressed.

The most important concern expressed is that PHIUS+ 2018 appears to move away from the core principle of passive building—that being conservation first and foremost. Rest assured: that principle remains at the core of PHIUS+ 2018. As with PHIUS+ 2015, the foundation of PHIUS+ 2018 is cost-optimized on-site conservation. That core principle is baked into the PHIUS+ 2018 standard, WUFI Passive and heating/cooling energy targets.

Cover image of Certification Guidebook and link to download PDF.

Click to review the update in Section 3.3 of the Certification Guidebook

PHIUS+ 2018 goes further by requiring steps toward net zero source energy, with a mind to carbon reduction. What’s new is that project teams now can also choose offsite renewable energy sources to meet the source energy target.

Despite that change, the core conservation principle never went away—conservation targets on heating and cooling energy still must be achieved using passive measures under PHIUS+ 2018 first.

Some of you have also raised concerns about situations where it’s difficult to go beyond on-site conservation. In particular, high unit density can be problematic. For these circumstances, PHIUS is adding the PHIUS+ Core certification path. Project teams can achieve PHIUS+ Core certification with strictly on-site measures. See Section 3.3 of the updated Guidebook for details.

And, we welcome your input—use the form below to comment.

Regards,

Katrin Klingenberg, PHIUS Executive Director

What’s new in WUFI Passive 3.2

Lisa White

Lisa White

By Lisa White, PHIUS Certification Manager

The PHIUS Certification Staff and PHIUS Technical Committee have been hard at work collaborating with the Fraunhofer Institute for Building Physics (IBP) to upgrade WUFI® Passive. And now, I’m happy to report that the Fraunhofer IBP has released WUFI Passive version 3.2!

This upgrade comes with many improvements, including full support of PHIUS+ 2018 modeling protocols and performance requirements. WUFI Passive is the only accepted modeling tool for PHIUS+ 2018 certification. Below is a summary of updates. Refer to the PHIUS+ Certification Guidebook v2.0, Section 6 for further details.

PHIUS+ 2018 Compliance Updates

PHIUS+ 2018 Criteria Calculator:

Space conditioning targets for a project can be calculated externally using PHIUS+ 2018 Space Conditioning Calculator or calculated within the software when PHIUS+ climate data, HDD65, CDD50, and marginal electricity price in $/kWh are input.

Source Energy Factors:
The source energy factors for electricity were updated, which dropped from 3.16 to 2.8 for the US, and to 1.96 for Canada.

Source Energy Targets:
The residential and non-residential source energy targets have been updated for PHIUS+ 2018. Source energy allowances for process loads in non-residential buildings can also be included in the reported target to verify compliance. See more on ‘Process Load Accounting’ below.

Air-Tightness Limit:
The air-tightness limit under PHIUS+ 2018 has been updated to 0.060 cfm50/ft2 for most buildings. For buildings 5+ stories of ‘Non-Combustible Materials’, there is now an adjusted target reported at 0.080 cfm50/ft2.

Renewable Energy Systems:
New options are included for modeling off-site renewable energy. The options are built in with the appropriate utilization factors according to PHIUS+ 2018 protocols.

DHW Calculation Methods:

PHIUS+ 2018 implements a new calculation method for hot water energy use of appliances, hot water distribution, and drain water heat recovery. See more under Technical Updates.

Technical Updates

Shading Calculation from Visualized Geometry:

WUFI Passive now harnesses capabilities of WUFIplus’ dynamic shading calculation to determine monthly shading factors based on the 3D visualized geometry. This includes shading from the building itself as well as any other surrounding structures that shade the building.

This calculation only takes a few seconds and greatly reduces the need for numerical shading inputs — speeding up the entire modeling process.

shading 3

Reveal Shading visualized:

Due to the new shading method described above, reveal or “in-set” shading for windows is now visualized in the 3D geometry when entered numerically.

Overhangs include ‘side spacing’:

Sometimes overhang depth and position are still in design and it’s easier if they aren’t included in the imported 3D geometry. They can still be input numerically. There is now the option to numerically enter an overhang that spans horizontally wider than the window width or is continuous across a façade.

shading 5

Removed shading landscape obstructions:

Due to the new dynamic shading method, horizontal/landscape obstruction entries have been removed. These may now be visualized in the 3D geometry instead.Accounting for these numerically with the new shading method is a work in progress and will be updated in the future.

Dishwashers, Clothes Washers, Clothes Dryers:

Annual energy consumption and hot water consumption for clothes washers, dishwashers, and dryers now follows ANSI/RESNET 301-2014 protocol, and the required inputs align directly with Energy Star ratings.

New Calculation Method for DHW Distribution:

New and improved methodology for designing and modeling DHW distribution has been implemented. The new method accounts for insulation on non-recirculating pipes, low flow fixtures, can more appropriately estimate hot water distribution losses from on-demand recirculation systems, and includes a tool to aid in the design of a DHW distribution network that will pass the on-site EPA WaterSense delivery test.

DHW 2

Drain Water Heat Recovery:

Drain water heat recovery can be an effective strategy in saving water heating energy by pre-heating incoming water with waste heat from shower drains, etc. A new mechanical system ‘device’ was added to support the calculation of drain water heat recovery when present

Process Load Accounting in Non-Residential Buildings:

A new tab under Internal Loads has been included to account for process loads. This allows for designating loads in the model as process loads. There is then the reporting option to include/remove them within the site & source energy results, and the option to increase the source energy allowance to include that load.

Process Loads 1

*Note: All process load allowances must be approved by PHIUS.

Modeling ‘Undefined’ or ‘White Box’ spaces:
A new non-residential occupancy mode was implemented to support modeling of Undefined spaces, i.e. in mixed-use buildings when a tenant is not yet determined. This simplifies one of PHIUS’ paths to certifying a mixed-use building.

User Friendliness

New Report: Site Energy Monthly Report

In addition to the existing results reports, a new report has been added to support comparison vs monthly utility bills. Previously in version 3.1.1, total annual Site and Source Energy use reports were available. This new report breaks the annual energy use into monthly estimates for both electricity and gas.

Site Energy 1

Updated Tool Tips:

The hover-over hints have been updated to align with PHIUS+ 2018 protocol. Activate them under Options>Usability>Tool Tip.

Case Name in footer of Reports:

In results reports, the project/case name was previously only shown on page 1. Now, you can activate the case name to be included in the footer of each page of the report. Activate under Options>Usability> Show project/case in footnote.

How to Update

Users of the professional version WUFI Passive 3.1 can download the update free of charge. Please log in to your account at the WUFI Web shop, there you can find the update link in the “My Orders” menu.

Free Tutorials: If you’re a beginner in WUFI Passive, utilize these free bite-size tutorials to guide you through your first model — http://www.phius.org/phius-certification-for-buildings-products/wufi-passive-tutorials

New capabilities in  v3.1:

New Heat Pump Device Types:

Two new devices have been added that follow PHIUS’ heat pump protocol. One for a Heat Pump Water Heater (with indoor compressor), and one that utilizes multiple heating COP ratings based on ambient conditions.

Data Recovery:

This is an auto-save feature that allows the user to define how often they want a file to auto-save, and how many ‘total’ files are saved (older versions from the same session drop off). Activate under Options>Usability.

Comment box:
Fraunhofer IBP implemented a comment box which allows users to add a unique comment to each input screen in the software. It can be used to remind yourself of a potential assumption that was made for an entry or use it as a log for model updates due to a change in design. If you’re submitting the project for PHIUS+ Certification, you can provide explanation for entries right in the software (though the feedback form is still the primary communication channel).

F1 for help files:
Before version 3.1, the WUFI Passive manual was a document external to WUFI Passive. The help files have been expanded and are integrated directly into the user interface! This feature can be accessed for any user input screen at any time using ‘F1’. There is an abundance of guidance here – take advantage of it, especially if you’re a first-time user.

Assign Data Button:
Along the top of the screen, an [Assign Data] button allows you to assign an entry (window type, shading entries, etc.) to multiple components at once. Huge time saver.

Export into XML File/Import from XML File:
User defined entries in your databases can be exported to an XML file and then can be shared with colleagues and (WUFI-friendly) friends. This includes all assemblies, materials, windows, HVAC devices, climates, etc. that have been created. Go to ‘Database>Export to XML’, and then select all items that you would like to be saved as an external XML file. If you receive an XML file, go to ‘Database > Import from XML’.

 

PHIUS+ 2018 Webinar Q&A

Screen Shot 2018-12-11 at 10.44.53 AM

PHIUS Senior Scientist Graham Wright and Certification Manager Lisa White answer questions that were submitted during and after the live PHIUS+ 2018 Webinar on November 8, 2018.

You can view a recording of the webinar at the PHIUS.org site.

*Note: Some questions have been edited for publication

Q: Has PHIUS started to look at overall GWP in the materials used to make these high performance buildings? To save the balance of the climate, reducing our emissions in the next 20 years is critical. Lots of XPS and spray foam make a low energy building but don’t do anything to help our climate goals.

A: The short answer is yes. We do have a GWP impact calculator for insulation. Its use is not required for project certification but we encourage it when we see large areas of XPS or SPF proposed. Our product certification program for construction systems has a requirement for a sustainability or health certification; there are several options recognized.

Q: Can you explain the exuberance concept?

A: We remain enthusiastic about the “tiny heating system” / “tiny heating bill” idea.

Q: Thanks for including Quebec Province! I believe in 2015+, all of North America was calculated according to a blanket value for cleanliness of the grid. Is 2018 adapted to different grids, and how do you deal with Quebec’s very cheap and clean hydroelectricity? Renewables are a tough sell here. Zero government incentives and at 7 cents/kWh, our energy costs would have to more than treble in order to make PV make financial sense.

A: In the standard-setting study itself we used the same factor all the time, but because the buildings were (almost) all electric, it canceled out. The PV generation is multiplied by the same factor as the usage, so source net zero is achieved with the same size PV array as for site net zero.

The philosophy is that CO2 emissions anywhere affect everyone everywhere. We all share one atmosphere, so by a principle of solidarity we should really use the world average source energy factor for electricity. That is, people with clean grids do not get to play “we’ve got ours” and use more energy. Even if your local grid is clean we want to drive additional action such as REC purchases that fund new clean energy projects. In certification we do allow the use of national averages, so we actually just request solidarity at the national level. Canada has a cleaner grid than the US overall, and thus Canadian projects will not have to take as many measures for net source energy reduction. The source energy factor for electricity in Canada is 1.96, whereas it is 2.8 for the US.

The electricity cost does affect some of the space conditioning criteria because higher energy prices justify more conservation measures and thus tighter targets. We calculate this with state-by-state averages, so Quebec projects will have less stringent targets than neighbors in Maine and Vermont.

 

Q: The word “townhouse” usually means a single-family building, but you seem to be using it differently.

A: The individual dwelling units are “single-family, attached”. That is, they share walls but not floor/ceiling. Speaking loosely, the whole row of attached units is the Townhouse, and the study building is 8 or 16 attached units.

Q: Is the mandatory minimum for window upgrades done because it wouldn’t be cost effective otherwise?

A: Yes. Window costs have come down but this still had to be forced in most cases. The starting points were still “in the money” though. There were a few times when the optimizer bought them on its own, but it took a long heating season and high energy price to motivate it. 

 

Q: Is this modeled EUI directly from WUFI Passive in the “Modeled vs. Measured” slide?

A: Yes, the WUFI Passive energy model used for certification.

Q: Do the new non-residential commissioning requirements apply to the common areas of residential buildings or only to all non-residential buildings?

A: TBD. Our current definition (for source energy target purposes) hinges on whether the spaces serve outside clients / customers or just the residents.

 

Q: Are you considering using the last 5 years of climate data vs ASHRAE to deal with global weirdness?

A: No, but we are working on future climate data for 2090 as an informational resource.

 

Q: Any comments on using low-iron glass (easily found in EU / just starting to appear in US)? Does the visible transmittance increase relative to ordinary US glass (which has a green tint to natural light)?

A: Alpen for a while had a low-iron glass option in their certified products, but they discontinued it.

 

Q: Instead of ignoring PV in competing with efficiency measures, why not look at PV with storage for the costs? This may not take care of seasonal differences, but it would take care of daily or weekly changes.

A: We may have have explored it if that was an option in BEopt, but it isn’t yet. Our current thinking is that what batteries do for you depends, in normal operation, on what the time-of-use rate structure looks like, and they are also good for you in outage situations. We are working on a calculation protocol for outages and waiting for utilities or other researchers to converge on time-of-use rate structure(s).

 

Q: Is there an ASHRAE 55 comfort analysis or PMV for PHIUS+?

A: The new window comfort calculator is based on relatively recent research on Predicted Percentage Dissatisfied specifically for draft at the ankle – it doesn’t just hark back to the PMV/PPD that was determined in 1970.

I (Graham) also wrote a paper for the 2016 conference looking at the radiant temperature effect of windows on comfort.

In certification we mostly take the same kind of simple view as in building code, e.g., “thou shalt maintain a dry bulb temperature set point of X and Y”. Sophisticated comfort analyses are more appropriate for workplace and nonresidential cases where clothing and metabolic profiles of occupants can be pinned down (as required by ASHRAE 55), and one might not have to worry so much about frail or sensitive occupants.

 

Comment: Adaptation is why I pursued CPHC in the first place!

Graham Wright: Thanks! Lisa presented on passive survivability at the Boston conference, and we will have more to say about this in the future.

Q: How does the new standard accommodate variable occupancy patterns/equipment usage in non-residential buildings?

A: With respect to the performance targets, as a first step, we will allow two different occupancies to be used to determine the annual demand targets vs. peak loads. Also, we can develop custom criteria for unusual situations (additional fee applies).

With respect to energy modeling protocol, it is already required to enter patterns for occupancy, ventilation and lighting, but this is mostly about getting the annual total energy right for source energy limit purposes.

 

Q: Please define HDD65, IGA, CDD50, TCD, IGCL and DDHR.

A: HDD65 = Heating degree-days, base 65 F;

IGA = Solar Irradiance, global, annual;

CDD50 = Cooling degree-days, base 50 F;

TCD = Temperature, cooling design day;

IGCL = Irradiance, global, cooling load design condition;

DDHR = Dehumidification design humidity ratio.

 

Q: If a project is considering registering under either 2015 or 2018, can we register under 2015 then change to 2018 (as circumstances change) without an additional registration fee?

A: Yes, you can always pursue a newer version of the standard. You are not able to pursue older versions if the contract date is later than the last day to submit under that older standard. In order to register for PHIUS+ 2015, the contract must be submitted before April 1, 2019.

 

Q: Are there updates to WUFI to accommodate the 2018+ standard? And when will it be available?

A: Yes, the next version of WUFI Passive will be released by the end of 2018. We will notify all of PHIUS’ mailing list.

 

 

 

 

 

 

 

 

NFRC Calculations Now Accepted for PHIUS Verified Window Performance Data Program

Graham S. Wright, Senior Scientist & Product Program Manager

window overview page image

 

PHIUS is pleased to announce the addition of a new path to performance data verification within our PHIUS Verified Window Performance Data Program. Based on the calculation standards of the US-based National Fenestration Rating Council (NFRC), this new compliance path offers an accurate and low-cost solution for manufacturers.

Previously in the PHIUS window program, window performance (U-value and solar heat gain coefficient) was only calculated based on European standards (EN/ ISO 10077-2 for frames/spacers, EN 673 for center-of-glass U-value, and EN 410 for solar heat gain.) Since the technical details of the EN standards differ from those of NFRC (which also have an ISO designation, ISO 15099), the performance numbers from the two methods could not be fairly compared. Although the technical sophistication of the EN and NFRC methods is similar, the actual NFRC labels give only whole-window properties for standard sizes and omit the component-level performance data needed by passive house modelers.

Now under the new program, domestic manufacturers who have already (or are currently pursuing) an NFRC rating can pursue this new calculation method in order to save time and money by avoiding additional calculation costs. The NFRC calculation method also allows performance numbers from North American products to be compared to those of European imports, thus giving passive house consultants and energy modelers performance numbers in a format that can be plugged directly into passive building modeling software WUFI Passive and the Passive House Planning Package (PHPP).

The “EN mode” of calculation will continue to be supported in the PHIUS window program. The EN method, referred to as “Orange Path”, is signified by an orange data label and noted in the border at the top of the label. As in the current program, pre-existing NFRC data files (for THERM and WINDOW) can serve as time-saving starting points for the EN-based calculations, but a significant amount of rework is needed due to the differences in method.

Orange Path data label, based on EN standards

Orange Path data label, based on EN standards

The label for the new “NFRC mode”, referred to as “Blue Path”, will have the same format and types of data listed as the EN mode label, but is signified by a blue data label. This path applies a conversion factor to the component-level data from the NFRC calculations.

Blue Path data label, based on NFRC standards

Blue Path data label, based on NFRC standards

PHIUS and NFRC jointly developed a program to train qualified NFRC simulators to run the proper conversion to produce the Blue Path data labels as an extension of their regular work on NFRC ratings. The conversion has two aspects – adjusting for the difference in standard window sizes, and for the different treatment of the extra heat loss at the edge of the glass due to the spacers. More details about the glass-edge translation can be found in a 2014 report entitled “NFRC and PHIUS U-factor Calculation Comparison” by Jeff Baker of WESTLab and NFRC. Verified product performance values are then provided to PHIUS by the NFRC modeler and published to the PHIUS Verified Window Performance Database.

PHIUS calculates the center-of-glass properties in a climate-dependent way, rather than using fixed environmental conditions, and incorporates climate-dependent recommendations on the data label. Since higher performance is required to get recommendations in more extreme climates, this provides “bragging rights” for manufacturers in addition to providing numbers for comparison-shopping and numbers for energy modeling.

For more information and to download the Program Overview and Program Application & Instructions in PDF, visit the PHIUS Verified Window Performance Data Program site. Find a qualified NFRC simulator here and submit your product for data verification today.

If you have any questions, please contact Graham Wright, Senior Scientist and Product Program Manager, at graham@passivehouse.us.

From Twin Countries to Twin Cities: China is Making Strides in Bringing Passive Building Mainstream

Katrin Klingenberg, PHIUS Executive Director

 

Passive House Alliance China’s 3rd China Passive Building Summit in Shanghai was followed up by a one-day expert meeting and workshop. The group rode out together to old town Shanghai, a nice area of the city consisting of mostly low-rise buildings. The fall weather had now finally turned a little nippy and drizzlier than the days before, and I was happy to have worn my jacket that day. Shanghai is unique: for two months out of the year (one each in the spring and fall), the temperatures are on the cool side, requiring no cooling and almost no heating, but the humidity is still too high to be comfortable.

The workshop was organized by Passive House Alliance China and took place onsite at a high-performance multifamily retrofit project located in a high-end gated community. Upon our arrival we were welcomed into a beautifully designed lobby where refreshments were being served to the invited stakeholders representing the construction industry and building science field from different cities in China. Following lunch, we had the opportunity to tour several of the completed high-performance apartments and begin to delve deeper into high-performance construction methods in mixed/humid climates with a focus on the cities in the Yangtze Delta. The main focus was on large-scale multifamily buildings, a rather typical and ubiquitous building typology throughout China.

If China and the US are country climate twins, then Shanghai is a close twin to Houston’s southeast Texas climate with the exception that Shanghai gets a little bit more rainfall. The most important challenges for passive design space conditioning solutions in these cities are not the thermal loads – it’s the humidity! Thermal loads are easily reduced to very low peaks by using passive design strategies such as moderate amounts of insulation (4 inches of mineral wool for a larger scale buildings will suffice), balanced ventilation with very good energy recovery efficiencies, excellent windows (double pane with thermally-broken frames), and passive level airtightness. But the high humidity load from ventilation during summer and the shoulder seasons can only be reduced so far. A significant dehumidification load remains, often during seasons when little or no cooling is required, as was the case while we were in China.

Improvements to the building envelope to minimize heating and cooling peaks also effects the ratio of sensible to latent cooling loads – resulting in the latent load becoming equal to or larger than the sensible load. While in less efficient buildings the sensible load far exceeds the latent load and can be taken care of by traditional cooling equipment, in highly efficient passive buildings it is the latent load that is now equal to or even dominant (see examples from Beijing and Hong Kong in the graphs below). This poses a new challenge for low-load comfort systems.

sensible-heat-ratio

The graphs illustrate how the sensible heat ratio decreases if the building envelope is improved for the climates of Beijing and Hong Kong. (slide credit: Hartwig Kuenzel, Fraunhofer IBP, NAPHC2015 keynote)

Climate specific targets also matter a great deal in this climate. In mixed climates, the right balance between heating and cooling targets becomes critical to avoid over-insulation and overheating risks. Window performance in mixed/humid climates needs to strike the right balance as well in order to not inadvertently increase cooling loads. Windows need to be optimized for both cases, heating and cooling, to perform at their best. In the climate of Shanghai as mentioned previously, good double pane windows with a lower solar heat gain coefficient and thermally broken frames are typically the right choice to meet comfort targets and to avoid contributing to overheating. Accurate assessment of internal gains must take into account culture, lifestyle, occupancy, and other factors as they have a significant impact on the overall energy balance of high-performance passive buildings.

In the case of China for example, cooking plays a major role in the vibrant Chinese lifestyle and culture, as we were lucky enough to experience first hand as our gracious hosts showed us the best and most interesting dining spots around Shanghai. Food is central to the culture and if folks are cooking a lot of flavorful and spiced foods in their homes in a climate with significant cooling loads, they will want directly vented kitchen exhaust hoods! Grease, odors, and heat need to get captured and thrown out right at the source. I was impressed to see a novel solution to this problem as we toured the retrofitted apartments. Each unit had two kitchens: one being the “real kitchen” with the big stove, prep area, and fridges which were separated from the main living space by sliding doors to minimize the negative indoor air impacts on the rest of the apartment, and the other one adjacent was an open kitchen concept with a bar for entertaining! What a brilliant idea (if you can afford it)!

Now, what about energy modeling? We have often said that more complex climates really should be modeled using dynamic whole building energy balancing tools such as WUFI Plus. What makes the climate more “complex”? Cooling and dehumidification is needed when the exterior temperature gets closer to the interior comfort zone and begins to fluctuate around it. The warm season is dominated by diurnally reversing heat and moisture flows – in during the cooler nighttime, and out during warmer daytime temperatures. Add moisture into this back and forth and it becomes really complex. To be able to accurately predict how components and the whole building will perform from an energy and hygrothermal perspective, the designer really needs to perform a dynamic whole-building energy model based on hourly data to make the right choices. In contrast, in a heating dominated climate, exterior temperatures are swinging far enough away from the interior thermal comfort zone so that heat and moisture flows are mostly flowing out. Static models are accurate enough for simpler climates such as this.

The graphs illustrate conditions for both heating and cooling/mixed climates. The static monthly balance method as employed by WUFI Passive is sufficiently accurate to predict energy use in a heating dominated climate. In cooling/mixed climates such as Shanghai and Houston, dynamic whole-building energy simulation (WUFI Plus) is recommended. (slide credit: Hartwig Kuenzel, Fraunhofer IBP, NAPHC2015 keynote)

The graphs illustrate conditions for both heating and cooling/mixed climates. The static monthly balance method as employed by WUFI Passive is sufficiently accurate to predict energy use in a heating dominated climate. In cooling/mixed climates such as Shanghai and Houston, dynamic whole-building energy simulation (WUFI Plus) is recommended. (slide credit: Hartwig Kuenzel, Fraunhofer IBP, NAPHC2015 keynote)

Hygrothermal wall performance checks should be best practice for passive designs in mixed/humid climates to avoid any kind of condensation risk. As China ramps up their energy efficiency efforts in varying climates to near passive building levels and experiments with materials it will be critical that these models are created as project teams might not be familiar with just yet or have no long term experience with this risk management in mixed/humid climates, which can lead to critical and significant failures.

Now, what about the high-performance apartment tour, where are the Chinese at with their high-performance solutions today?

I was thoroughly impressed with what they had already in place in terms of execution, performance, details, mechanical solutions, and – to top it all off – a standardized monitoring interface centrally located in the home providing constant feedback on thermal comfort and indoor air quality to the home owner including fine particulate matter (PM 2.5) and inside to outside air quality comparisons. In Shanghai it is often the case that outdoor conditions are worse than indoors due to high pollution levels.

The project we toured was a retrofitted five-story brick building that had been upgraded by adding a 4-inch layer of mineral wool exterior insulation, airtight layer, and a new clay tile façade. The reported tested air-tightness result was 1.5 ACH, which is very respectable for a retrofit! Space conditioning was solved in a very elegant and most comfortable way: a separate energy recovery balanced ventilation system with appropriate filtration and dedicated integrated dehumidification took care of controlling ventilation humidity loads and outdoor pollutants (as evidenced on the screen of the monitoring interface in the living room, see opening photo). Space conditioning was handled by a separate point source solution consisting of hydronic heating and cooling integrated into the room’s ceiling. Radiant heating and cooling is a more costly, yet very comfortable high-end solution. Controlled infiltration and humidity loads are key to this solution to avoid condensation. So is awareness by the homeowner. They need to be put on notice that they can’t cool the home and leave the beautiful lift and slide high-performance balcony door open at the same time!

The developer reported that the passive house approach works financially for them for the high-end market. As you might expect, two bedroom apartments were selling in the millions, as would be the case for similar real estate in any other cosmopolitan global city.

Can passive go mainstream in China?

If I may offer my personal prediction: the Chinese have taken a surprising global lead in fighting climate change and have identified aggressive conservation goals for buildings as a valid strategy. The government has passed mandates to local jurisdictions to find appropriate cost effective solutions. If China addresses the cost optimization of passive building measures based on varying climates, construction paradigms, and energy costs in China similarly to what PHIUS did in the US, then they should certainly be able to generate design guidelines aimed at presenting the most economical path to zero. At the rate that they are going, I believe China will bring passive building to the mainstream before he US does because they have the political will, effective materials and components, knowledge of building science and energy modeling, and cost effectiveness strategies to get there.

What about the state of typical mainstream construction in China?

From what we saw, most apartments in Shanghai already have their own air-to-air heating and cooling heat pump unit sitting on their balcony. Pair that common solution with good airtightness, balanced energy recovery with dedicated dehumidification, moderate amounts of insulation and appropriate hygrothermal wall design, good windows, and you are there.

It would be great to see China taking the lead!

 

– Katrin