Passivehaus or Passive House?

Lincoln Net Zero Farmhouse – designed to Passive House standards and LEED Platinum certified

What is a passive house? What is the difference between the two certification standards Passivhaus vs Passive House? What exactly makes a building “passive”?

First off, a Passive House does not necessarily mean a building is a “house” per se. Most certified Passive Houses at this point are residential, though Passive House Certification is available for other building types and passive building techniques are used in many energy efficient buildings today regardless if they are pursuing certification. Many passive homes look very similar to typical homes, with commonalities in design based on passive design strategies (see below). If you love the idea of passive design as much as I do, you’ll want to check out Earthships as well. Earthships are an extreme example of passive solar design and probably won’t work for every location, but they are pretty cool! They combine the use of rammed earth (massing), south facing glazing (orientation and passive heating) with natural ventilation and lighting.

A “typical” Earthship design.

A little history:

Passive buildings have been around for ages, since the beginning of human survival instincts we have sought out the most comfortable and economical structures as our shelter. For instance, caves and mud huts are “passive” structures as they maintain a comfortable standard temperature throughout the year, that stay warmer in the winter and cooler in the summer than outdoor temperatures. Passive buildings operate on the same principles. To design a passive building, you want to utilize passive strategies to reduce the need for mechanical heating and cooling to maintain comfort. The original certification program often used the idea of heating a home with the energy of a hair dryer to give a clear idea of what a passive building was trying to achieve.

The Passive House Certification originated as “Passivhaus” in Germany, in the 1990’s as a way to reduce the amount of energy consumed by a building through maximizing passive design strategies. Modern day passive style homes were built in the United Stares as far back as the 1940’s and with a large resurgence in the 1970’s and now today. Through understanding the changes in temperature throughout the year and setting strict guidelines for energy use, the founders of Passivhaus came up with limits to building energy used based on the climate in Germany.

But what makes a passive house, passive? The “passive” design strategies of course! Here are the basic passive design strategies utilized by both certified passive buildings and other high performing building:


  • Building Orientation – orienting the building and living spaces in an ideal alignment with the sun, will drive the energy use of the building. Based on latitude and how the sun hits the building, in combination with the building’s massing can greatly impact how interior temperatures are maintained.


  • Building Massing – the size, shape and material of a building can have a huge impact on how energy is transferred, stored, and held within the space. Similar to the original cave and mud hut idea, creating a specific mass or shape of the building can either minimize or maximize energy conservation measures. Depending on the climate and design, proper orientation and massing alone can help to maintain a constant indoor temperature with little need for additional heating and cooling.


  • Passive Heating – using orientation and massing, you can maximize solar gains. When the building is properly aligned with the sun, solar radiation can be used as the first heating source for the building. As the sun’s energy heats up the space through windows (on the south side in the northern hemisphere) massing and structure can capture and hold this energy warming the space without mechanical systems. (pay attention to SHGC – solar heat gain coefficient)


  • Passive Cooling – Natural Ventilation, air cooling and shading can greatly reduce the need for mechanical cooling. Opening windows on cool nights, can not only help to reduce the interior temperatures but also brings in fresh air directly to the living space. The use of evaporative and geothermal cooling strategies can also help with keeping the building comfortable. Solar shading can be used in addition to other passive cooling techniques to minimize solar radiation and glare throughout the summer. One natural example that is often used is the termite mound. Termite mounds are found in very hot climates, however , because of their design that uses passive cooling through natural ventilation and the stack effect, they maintain a cool interior temperature so the insects don’t overheat. This is both a massing and passive cooling technique that translates well to human dwellings.


  • Lighting/Daylighting – Not only is natural light free, but it’s preferable. Unless there is too much direct sunlight causing glare, most people typically prefere natural light to artificial light. Through proper placement of windows and the orientation of the building, you can maximize the building’s ability to capture natural light and minimize the need for artificial light.


  • Design Program – How are the spaces laid out within the building? Where will occupants spend the most time? Where are the best views? With proper layout of the rooms, spaces that are used most often can take advantage of daylighting, passive heating/cooling, massing and orientation. Typically living rooms, kitchens and other gathering spaces are better placed on areas with desireable views and/or the south side of the building to take advantage of passive strategies directly. Bathrooms, mechanical rooms, laundry etc. can be put on the northern side where there is typically less light.


Up until recently even new buildings leaked quite a lot of air. This was a benefit because it consistently brought in fresh air into the home, however it was a major waste of energy as much of the tempered air was lost through leaks and there was no real way to control air except through exhaust fans in bathrooms and kitchens. PassiveHouse certification and passive building design, require very an airtight building envelope, which limits uncontrolled leaking, and allows for a level of ACH (air changes per hour) for healthy indoor air quality. Since passive buildings don’t leak the way older buildings do, designers typically use HRVs (heat recovery ventilators) or ERVs (Energy Recovery Ventilators) to pull in fresh air and recycle some of the heat of the exhaust air. These systems are a very efficient technology that allows us to better control the airflow between the inside and outside.


Ok, so you want to build a Passive House. But What is the difference between Passivhaus  vs Passive House?

Passivhaus: (PHI)is the original German standard created in the 1990’s, that uses fixed parameters for energy demand for heating and cooling.

Passivhaus performance requirements:

  • Maximum annual heating & cooling demand: 4.75 kBTU per sqft/yr
  • Peak heating load: 3.17 BTU/
  • Peak cooling load: 2.54 BTU/
  • Maximum primary energy 38 lBTU/sqft/yr
  • Air infiltration rate no greater than 0.60 air changes per hour @ 50 Pa



 Passive House or PHIUS – Passive House Institute United States, is based off the German Standard, and was originally the US branch of PHI, however in 2011 the two organizations parted ways. Where the German standard has fixed requirements, PHIUS allows for varying energy demand allowances for heating and cooling based on local climate data. For instance, a home in Boston, Massachusetts would have different requirements than the same home build in Miami, Florida. In Germany, the country is fairly limited in climate variation, as compared with the United States where climate varies greatly, thus the need for variable heating and cooling allowances.


PHIUS Performance Requirement are as follows:

  • Residential Source Energy: ≤ (# of bedrooms +1) * (6200 kWh)/yr (kWh/person/yr)
  • Non Residential ≤ 38 kBTU/sqft iCFA/yr
  • Air infiltration (single family) ≤ 0.050 CFM/ sqft of gross enclosure area at 50 Pa
  • Multifamily Airtightness: ≤ 0.080 CFM/sqft of gross enclosure area at 50 Pa
  • Annual Heating Demand: ≤1.0-12.0 kBTU/sqft/iCFA/yr (climate specific)
  • Annual Cooling Demand: ≤1.0-21.4 kBTU/sqft/iCFA/yr (climate specific)
  • Peak Heating Demand: ≤0.8-5.4 kBTU/sqft/iCFA/yr (climate specific)
  • Peak Cooling Demand: ≤1.8-8.9 kBTU/sqft/iCFA/yr (climate specific)
  • Ventilation: 0.30 ACH minimum

So there are many ways to build a “passive” house, whether it is certified or not will depend on how strictly you want to stick to meeting the performance targets and what type of design you are interested in. I would always recommend going for certification as you get added benefits of hygrothermal analysis and more attention paid to thermal bridges in the envelope.

So where should you start? If you are in the United States, you’ll want to look into contacting a local CPHC (Certified Passive House Consultant) to help you get stared. PHIUS is really the best program for US projects, though there still are projects going ahead with the German standard. You’ll also need a Passive House Rater to perform the on-site performance testing. You can the integrate passive strategies into the design through working with your architect and CPHC to meet both the aesthetic and passive house requirements.

You can email me directly for questions and consulting on Passive House projects.



Healthy Building Materials Research

Building Products Material Vetting: Looking at product health, hazards and sustainability.

With today’s options for building materials, picking the right product can prove difficult, even if you know what you are looking for. This article will examine the changes happening in the building materials industry and provide guidance on selecting products that will meet the goals of your project.

In recent years, the increased awareness in sustainable design has broadened industry wide concerns with the health hazardous of building materials. As with past products contained harmful chemicals such as asbestos, PCBs and formaldehyde, building designers understand that not all products are created equal, and many products are not fully vetted for human and environmental health effects until years after they have been installed in millions of buildings. So as health concerns continue, understanding what chemicals are in our building products is moving up on the priority list and becoming just as important as knowing what is in the food we eat. Many programs and certifications have evolved to evaluate products for chemical composition, environmental and human health which are helping to allow professionals to cross compare products.

In the last ten to twenty years, the Passive House (Passivehaus) standard and energy efficient design strategies have made airtightness a greater priority to achieve higher levels of energy efficiency. However, with a tighter building envelope, there is less natural air leakage and less fresh outside air coming in. We need tight envelopes to maintain comfortable temperatures, while minimizing heating and cooling output. Though one of the problems with building tighter is that many of the products we put into our buildings, are full of harmful chemicals. Once installed, many chemicals off-gas into the building and contaminate the indoor air. Where older leaky buildings allowed for these chemicals to flow out of the house, newer buildings must now integrate efficient mechanical air ventilation strategies in order to reduce chemicals and improve indoor air quality while still maintaining interior temperatures. In addition to building energy efficiency, increased concerns for overall human health and wellness are playing a big part in moving the building materials industry into a realm of greater transparency and concern for what exactly goes into each product. So if we can easily select products that don’t contain known chemicals of concern, or maximize the use of natural ingredients, less concern needs to be paid to what might be in the air of our home or office.

With millions of building products on the market today, it’s often difficult to know where to start. For do-it yourself-ers and smaller builders, what’s available at Home Depot and Lowes typically determines which products get used, with little regard for material health or sustainability. For commercial and larger scale projects, the search for the perfect product can seem almost infinite. Every day more products become available, and there is a overabundance of differnt claims of sustainable and healthier products: PVC free, NAUF, GreenGuard Certified, recycled content %, FSC, FloorScore, low VOC, etc. . There are literally thousands different criteria which get applied to products, which continue to make product comparisons more difficult. Material selection has never been a quick and easy process, but with all the additional requirements, certifications and health concerns it is quickly becoming an almost impossible task for architects and developers to be sure they are selecting the best of the best. It seems at this point, understanding building product hazards and sustainability criteria could be a university major all in itself, so the items below will simplify the process a bit to give you a better understanding of the factors at play, so you’ll be able to set realistic goals for your project.

Material Health vs. Sustainability:

Signature Sustainability has recently been providing full material product vetting for a developer in New York City. The scope of the project consisted of a full review of material sections of the specifications. Focus was given to products that have direct interaction with building occupants, such as flooring materials, counter tops, wall and ceiling materials in addition to several other more indirect products like caulking, shop applied coatings, flame retardants and adhesives. The main goal of the client was to provide a building that was considerably “healthier” than that of a standard building. Through the careful vetting of product health and sustainability criteria, we assisted the client with reviewing materials and recommending the products with the least hazardous chemicals and greatest environmental certifications or manufacturing processes.

Although we looked at both health and sustainability, the client wanted health criteria to be priority over sustainability. When attempting to select the best product in a material category, there were times when we needed to consider health criteria over sustainability in order to meet the client’s goals. When reviewing gypsum board, we knew that there is typically a large amount of recycled content, which met the project’s sustainability goals. The unfortunate discovery, is that the recycled content in gypsum board is far more hazardous than natural gypsum. (A side note: most gypsum wallboard on the east coast uses FGD (Fuel Gas Desulfurization) as replacement filler for natural gypsum. FGD is a process used to remove sulfur dioxide from fossil fuel power plants, and the material collected in the scrubbers now makes up a large portion of the recycled content in much of the east coast gypsum board. Gypsum from the west coast however, is typically natural gypsum and thus free of any FGD material.) Some research suggests that synthetic gypsum is not harmful, while other reports state that mercury and other metals are present in the product. So, in order to align with the client’s goals of improved building health, we needed to select a product with as little recycled content as possible. In this case, a product with no recycled content was actually the preferable choice. The hope is that the industry progresses, manufacturer’s will provide products meeting both health and sustainability criteria, rather than having to forgo one or the other.


Material Hazards:

In order to help to weed out products with harmful chemicals and push manufacturer’s to meet higher thresholds of material health and sustainability, many certifications and standards have evolved to make identifying products easier. The problem with so many certifications is that it can often be an overwhelming task to determine what programs apply to the material and which certifications are most effective at ensuring material health.

There are now hundreds of material health attributes to consider, some of the more popular are:

  1. VOC content (grams per liter g/l) – Standard in evaluating paints, coatings, sealants, adhesives. Volatile Organic Compounds are chemicals which easily become vapor and “off-gas” chemicals into the air.
  1. Building Product Certifications:

a. FloorScore – Flooring Products, adhesives and underlayments

b. Declare Label – Living Futures Institute Certification (all product types)

c. GreenGuard Gold – Many Material Categories

d. Green Screen – Chemical Hazard Assessment

e. CRI Green Label & Green Label Plus+ – Carpet, Carpet Pad, adhesives

f. Cradle To Cradle – Environmental Life Cycle Analysis

g. Cradle To Cradle – Material Health Evaluations

h. SCS Indoor Advantage – Building Products, Furniture

  1. Environmental Product Declarations (EPDs): documents that provide additional environmental product life cycle analysis information and global warming potential information.
  1. Health Product Declarations (HPDs): documents, which indicate the percentage and type of chemicals used in production along with associated hazards. (expanded beyond what is covered in MSDS or SDS)
  1. SDS & MSDS (Safety Data Sheets & Material Safety Data Sheets) – standard building product health criteria and emergency information.
  1. Typical Chemicals of Concern:
    1. Mercury
    2. Lead
    3. Flame Retardants (Polybrominated diphenyl ethers (PBDEs))
    4. Polychlorinated biphenyls (PCBs)
    5. Chlorinated Pesticides
    6. Phthalates (PVC)
    7. Formaldehyde
    8. Anti-microbials
    9. Fly-ash or FGD
    10. The Red List (Living Futures Institute and Declare Labels) this list includes a preselected list of chemicals of concern. These chemicals are banned from use on Living Building Challenge projects.
  1. Indoor air standards: CDPH 01350 – California Department of Public Health sets standards for environmental and public health considerations. Some key elements focus on indoor air criteria used by GreenGuard and other certification programs as a baseline for improved indoor air quality standards.
  1. Database: Pharos Project – “combines manufacturer transparency and independent research to provide in-depth health and environmental information about a wide range of building products.”

Material Sustainability:

With so many levels of health and sustainability criteria to consider, selecting the right product can seem daunting. How do you ensure you select the most sustainable product for environmental health, in addition to making sure you don’t select a product that might contain known carcinogens, while also ensuring the product will earn you credit towards LEED, WELL or Living Building Challenge or meet your general project goals? You may want to dive in and do the research yourself, but be sure to take that time into consideration. Hundreds, if not thousands of hours can be spent researching products in order to determine what is available and what meets your project’s requirements. Signature Sustainability well versed in building materials vetting and understand the importance of selecting the least hazardous and most sustainable products. It may be wise to make a list of the products you are most concerned with and start there.

When looking at the environmental sustainability of products, the best products tend to be from manufacturers that provide transparency about what goes into their manufacturing process. If there are no harmful chemicals in a product a manufacturer shouldn’t’ be worried about disclosing what is in the product on a Health Product Declaration (HPD). If the manufacturing process limits transportation, uses recycled or rapidly renewable products the Environmental Product Declaration (EPD) will indicate as such.

Some of the current standard sustainability criteria of products:

  1. FSC WOOD – (Forest Stewardship Council): sustainably harvested wood, invoices should indicate a Chain of Custody number (COC).
  1. Recycled Content – varies from pre-consumer (post industrial) and post-consumer (pre-industrial). Ask your manufacturer what makes up the reused material.
  1. Biobased content – many products are manufactured using waste from the agriculture industry. Materials that are derived from biomass resources. (Organic materials such as crop residues, wood residues, grasses and aquatic plants.) The USDA has created standards for “BioPrefered” products. More information in the link.
  1. Rapidly Renewable – products which are able to regenerate in less than 10 years
  1. Product Transparency: HPDs and EPDs – these documents provide product disclosure for health and environmental criteria provided by manufacturer’s and third party testing agencies.
  1. Local Products – products manufactured as close to the project site are beneficial in that they support the local economy as well as reduce distances required for transportation, cutting down on total life cycle carbon emissions.
  2. Energy Star – Energy Efficient Appliances

In closing, there are always choices to be made with regards to a specific project goals and needs. Currently, the industry is undergoing a important shift towards improved wellbeing and sustainable criteria. As the demand for products that meet enhanced levels of health and environmental standards increase, manufacturers will continue to shift their focus to modifying their products to follow suit. It is important to call your manufacturer representatives and speak with them about what your project is looking to do and what type of documentation and criteria you are looking for. Many of our conversations with manufacturers have been beneficial to educating them on changes in the industry and allows them the choice to pursue new methods of product creation and chemistry. Communication is key toward getting the product supply to catch up with the demand for better building products. Material vetting may always be an overwhelming task, but product databases like Pharos, certifications and transparency should help to make it easier in the years to come.


If you have any questions, please don’t hesitate to reach out: