Perlita House: The First Passive House Building in Los Angeles

April 01, 2019
Spring 2019
A version of this article appears in the Spring 2019 issue of Home Energy Magazine.
Click here to read more articles about Multifamily

A few years after I finished building what I thought was my dream house in France, I discovered the Passive House International (PHI) standard and became very frustrated that I hadn’t known about it earlier.

Why Passive House?

According to the latest climate scientists’ report, published in October 2018, drastic weather changes, ocean rise, more forest fires, and other consequences will occur if we don’t limit total global warming to less than 2°C. To achieve this goal, we need to change our ways of living now. According to climate scientists, the target is to reduce our CO2 emissions by 45% by 2030 and to reach carbon neutrality by 2050. The PHI standard that began to be developed in the early 1990s has proven to reduce a home’s heating-and-cooling demand by up to 90%, and to reduce up to 75% of the total energy consumption of buildings, depending on the climate. More than 80,000 buildings all around the world, in every climate zone—single-family homes, apartment buildings, office buildings, hospitals, schools, museums, and more—are built to the PHI standard. But this is still nothing compared to the several billions of new square feet built each year, and even less when you consider that there are approximately 120 million existing buildings in the United States alone.

Perlita House—after. (Xavier Gaucher)

So when communities that are really serious about meeting the international COP21 standards—the 21st United Nations Climate Change Conference in France in 2015, or Conference of the Parties (COP21)—discover the PHI standard, they have a clear and reliable path to reducing almost half of their carbon emissions by building or renovating every building to conform to that standard (45% of CO2 emissions are emitted from buildings). This is, for example, what Vancouver started to do a few years ago. New buildings are to be zero emission by 2030 and using PHI standards will help them get there.

Perlita Passive House

When I learned about the PHI standard, I did not understand why every single building wasn’t built to that standard. As a mechanical engineer, I wanted to get the training to help design and build houses using the standard. In 2014, I took the Certified Passive House Designer and Consultant training. And I decided that my next house would be a Passive House.

So when I moved with my family to Los Angeles, that was all I had in mind. In the summer of 2015, we found a house to renovate in the location we wanted (because the PHI standard works for retrofit as well as for new construction). And I set to work.

We have now been living in the Perlita Passive House—the first Passive House in the Los Angeles area–for a full 12 months, and I am now able to share real operational results. I can confirm that the PHI standard performs in this area as well as it does in all the cities that are adopting it around the world—from Brussels to Dublin, from New York to Vancouver.

First off, how is our house different from standard construction in California?

  1. It has more insulation in the walls, the roof, and the floor.
  2. It has fewer thermal bridges. This is done by making sure that the thermal envelope is continuous.
  3. It has a very airtight envelope (blower door tested at 0.6 ACH50 maximum, as compared to an average of about 6 ACH50 for conventional new construction, equivalent to a 16-inch hole in the building envelope).
  4. It has highly efficient windows with appropriate
  5. It has continuous fresh air and exhaust ventilation to ensure proper indoor air quality (IAQ).

Perlita House—before. (Kirk Gerou)

All of these attributes enable our house to meet the PHI energy consumption criteria. These criteria are maximum heating demand 4.75 kBtu per square foot per year; maximum cooling demand 4.75k Btu per square foot per year, plus the dehumidification contribution related to the local climate (0 in our case); and maximum energy use intensity (EUI) 14.8 kBtu per square foot per year.

A simple but detailed energy modeling tool, the Passive House Planning Package (PHPP), helps you to determine the insulation R-value, window efficiency, air-conditioning system, and ventilation unit required to meet these criteria. Table 1 shows how the Perlita house compares to Title 24 California Code requirements with respect to R-value and ACH50.

Table 1. Perlita House and California Code

Los Angeles—Climate Zone 9

Perlita Passive House

Title 24—2013

R-value walls

R-15 + R-13 insulation

R-13 insulation

R-value floor

R-21 insulation

R-19 insulation

R-value roof

R-38 insulation

R-30 insulation

R-value window



Air Leakage, ACH50

≤ 1.0 for retrofit

6 approx.
(No requirement)

Our PHPP requirements were not far off the current Title 24 California Code requirements, and should lower our heating and cooling demand by 63%. (It is hard to tell precisely, since the monitoring system does not give a breakdown just for the HVAC unit; but we are close to our overall energy use goal, and our 1-ton HVAC unit does the job. So we are on track.)

The main differences between Perlita House and Title 24 were as follows:

  1. We increased the required R-value a little for the roof and the floor and added an extra layer of insulation for the walls.
  2. We installed high-performance double-paned windows and doors. The most difficult part was to find airtight ones, since the National Fenestration Rating Council air leakage test is optional.
  3. We made the envelope airtight. While this was the most challenging part of the job, it also made for the biggest improvement over Title 24 requirements.
  4. We installed an efficient ventilation system.

The overall additional cost was 3.6% more than normal construction, including the Passive House modeling and consulting fees and taking into account the savings from a smaller heating-and-cooling unit requirement.

However, it is critical to note that Passive House is not a typical cost-plus paradigm. If you take a typical building and simply try to make it a Passive House building—yes, it could cost more. But if you start from the beginning of the design process and fully integrate Passive House goals, on average PH can even cost a little less than standard construction (see Figure 1).

Figure 1. If you start from the beginning of the design process and fully integrate Passive House goals, the average cost can even be a little lower than standard construction. (Xavier Gaucher)

Living Well in a Passive House

During the Christmas holidays we stayed at some relatives’ house, and that’s when my wife, my son, and I realized the advantages of living in our Passive House for the last year. Unlike our relatives’ conventional house, our house isn’t cold when we get up in the middle of the night or in the morning. The HVAC popping on in the middle of the night does not wake us up; in our house we don’t even hear our small 1-ton heat pump, which barely ran during the entire winter or even during the summer unless it was over 100°F outdoors; and the upstairs does not get warmer than the downstairs. All three of us had forgotten those issues; it is amazing how well one adjusts to comfort!

After we moved into our new house, we had friends stay with us and our two large cats. As it happens, several of them were highly allergic to cats; they had expected to suffer and to have to take strong medicine. But not one of them experienced an allergic reaction. The only explanation is that the continuous ventilation required in PHI buildings provides a silent, but constant, fresh air supply that maintains a very high IAQ. With equal amounts (120 CFM50) of fresh air and exhaust air, we can always maintain our CO2 level way below 1,000 ppm, compared to standard-built homes, where it is common to regularly exceed 3,000 ppm.

Second layer of wall insulation before drywall. (Xavier Gaucher)

Another comfort benefit we are experiencing is that we no longer hear the city noises, thanks to our house’s airtight envelope, high-efficiency windows, and extra insulation. Even helicopters flying at night (ubiquitous in Los Angeles) don’t wake us up anymore.

Then every two months we receive our energy bill, and
we realize how well Passive House and net zero energy work together.

Integrating Solar, Going All-Electric

Renewable energy has been fully integrated into PHI standards since 2015, when PHI developed the primary energy renewable (PER) factor and added two new certification classes: Passive House Plus, roughly equivalent to net zero, and Passive House Premium, equivalent to carbon zero. The original Passive House standard without renewable energy was rebranded as Passive House Classic.

So on-site solar panels were not a requirement to certify our house, but we designed it to have an unshaded roof almost perfectly facing south for solar panel placement, since in California, starting in 2020, all new residential buildings up to four stories will have to be net zero (to produce at least as much energy from renewables as the building uses over a 12-month period). Our PHPP modeling called for ten panels to reach Passive House Plus or net zero for our 2,120 ft2 all-electric fossil-fuel-free house.

During the renovation process, we removed the gas line to the house, which was no longer needed. Induction cooking works better and is safer than gas; our heat-pump water heater works perfectly and cools the unconditioned basement which existed when we bought the house—perfect for wine storage. Using a heat pump for heating and A/C was cheaper than adding a furnace for heating alone. And our electric ventless clothes dryer works perfectly and was easy to install. So not only do we now not emit CO2, but we also have a healthier and safer house.

We also decided to get a small used electric car and calculated the need for four more solar panels to supply the electricity that our local commute of about 7,500 miles per year would require.

So we were looking at a solar array of 16 360W panels. Without enough historical data, and considering how much cooking we do and allowing a safety factor for house consumption, we added two extra solar panels to the ten required by PHI. Over the last 12 months (our solar panels kicked in on January 11, 2018), we produced 10,240 kWh (see Figure 2). On January 11, 2019, our electric meter showed that we had received from the grid 3,864 kWh and exported to the grid 5,095 kWh. We used 1,384 kWh for the electric car that we purchased in April, so this means that we used 7,575 kWh for the house, without paying any special attention to our usage or changing any of our habits. I suspect that much of the 20% difference between my modeling numbers and the actual figures is attributable to the fact that we did more cooking than we had anticipated, since we are enjoying our new kitchen space and entertaining often. I will be investigating our energy use further; I plan to start by finding an affordable monitoring system that takes into account the storage battery.

Figure 2. In one year, the Perlita Passive House generated more energy than was used in the home—including the power used to charge an electric car. (Xavier Gaucher)c

According to these numbers, the Perlita Passive House was net zero energy this year with only 12 solar panels, for an all-electric 2,120 ft2 house. Our final EUI was calculated at 12.1 kBtu per square foot per year. According to the LA Energy Atlas, developed by the California Center for Sustainable Communities at UCLA, the average energy consumption for single-family houses is 44.9 kBtu per square foot per year. This corresponds to an energy consumption almost 4 times higher than our Passive House, which means 4 times more solar panels to reach net zero. Looking only at buildings built after 1990, the average EUI is 33.4 kBtu per square foot per year, which is still almost 3 times higher and means 3 times more solar panels to reach net zero.

The EUI for buildings could be compared to miles per gallon for cars. The most energy-efficient gas car uses “only” one-third as much fuel as the worst gas guzzler (18 mpg versus 55 mpg for mixed city and highway use). When CO2 emissions for buildings are higher than CO2 emissions for cars, we need to start looking at building efficiency much more seriously than we do now.

For various reasons, including the fact that it is required for the Living Building Challenge certification we are doing, in addition to our Passive House certification, we installed a 13.5 kWh storage battery in mid-April. The battery allows the house to be off-grid about 70% of the time, so I looked at what it would take to make it 100% off-grid. In order to cover that 30% gap, we would need ten more solar panels and two additional storage batteries. After making that calculation and estimating the corresponding cost, I was very happy to have to pay at present only $11 a month of minimum charge to my utility company. It also shows the challenge the utility companies are facing while switching to the fossil fuel free grid we need, especially in terms of storage capacity. At present, there is no return on investment for electricity storage batteries. This will probably change as we move more and more toward an all-renewable grid, and as time-of-use peak rates continue to increase. For now, the best batteries are comfort storage batteries—that is, Passive House buildings. Improving building performance is essential if we want to see a carbon-free world.

Second layer of wall insulation before drywall. (Xavier Gaucher)

What’s Next?

I know that the Perlita Passive House won’t save the world, but I hope our project is inspiring as many people as possible to start making PHI the new construction standard in California. This is what the amazing PHI community of about 10,000 people from around the world is doing every day.

In terms of changes that our society, which includes each one of us individually, needs to make, changing the way we erect and renovate buildings is probably the easiest. We already have the solutions that bring more than just comfort and very low energy bills. PHI makes economic sense; it creates jobs and gives those jobs a new meaning for contractors building and renovating houses in the field; and it gives a meaning to those “sustainable” and “green” designations that I see too often without really understanding what they mean.

What’s next? Today, building operation represents 90% of the CO2 emissions in the building life cycle assessment, while less than 10% comes from building construction. However, when you reduce emissions related to operation by 75%, the emissions related to construction—mainly from construction materials—suddenly represent one-third of building emissions. So the next step for our industry is to reduce CO2 emissions from building construction—which will also help to conserve our limited natural resources. Two examples: The cement industry alone accounts for 5% of the world’s total CO2 emissions; and available natural resources won’t be sufficient to manufacture all the solar panels and storage batteries we will need, if we don’t significantly increase our buildings’ efficiency.

learn more

To learn more about the Perlita Passive House.

I am returning to France in three years. However, my goal before I leave is to begin as many Passive House buildings in the Los Angeles area and in California aspossible, and to share my experience of Passive House building with architects and designers. Vancouver has set a record that I would like to see us beat. Vancouver had one single-family Passive House in 2015; by the end of 2018, it had 1,100 permitted Passive House buildings. Can we beat that in Los Angeles? The second Passive House in the Los Angeles area is already finished. Who is next?

Xavier Gaucher is a Certified Passive House Consultant and a board member of Passive House California.

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