Archive Monthly Archives: October 2015

Why We Chose Passive House

October 30, 2015

When bought the 88-year old bungalow in 2010 we didn't know about Passive House. Up until then, our notion of green sustainable house had been to install solar panels, use recycled materials, and use low flow water fixtures. I didn't "get" the importance and the advantage of having the house built like a thermos rather than a coffee maker. At that time, I felt that a green home was focused on using the materials considered green. Nobody we talked to seemed to be focused on the actual performance of the house.

We stumbled across Passive House in March of 2010 through a casual conversation. At first it didn't seem remarkable. We thought it was a type of passive solar home. We didn't quite get it because we didn't know the difference between site energy and source energy. Nor did we appreciate the fact that energy not used onsite is better than renewable energy produced onsite. It was before tools like this video that explains passive house in 90 seconds was out on YouTube.

It took a formal presentation that showed Passive House was based on solid building science and had an amazing track record before the light bulbs went off. We finally "got it"at the Passive House workshop in September 2010, six months after we first heard about Passive House. The case studies shared at the conference sealed the deal. You know that marketing saying about how a prospect needs to hear it 7 times before they take action? It was true for us. We needed to hear the message more than once before we got it. 

Here is a short excerpt from chapter 3 of Midori Haus book:

I get that. Running various what-if scenarios using software makes sense. What I didn’t get was what these numbers meant. I wasn’t impressed when I first heard of 15 kWh/m2 for heating and cooling per year to keep the house at comfortable 68°F. Without context the impressive benchmark information can simply breeze into one ear and escape from the other ear without the light bulb of comprehension turning on. It clicked for me when I saw the results from the case studies of homes built to Passive House Standard. Over and over these houses showed impressive results: 80 percent less energy use throughout the year than new homes built in the conventional way. It’s pretty convincing when the source of the data is the utility bills and the logs of temperature data corresponding to the billing period, which showed that the house was indeed comfortable. It wasn’t a case of vigilant people piling on sweaters and turning down the heat in the winter or living in a sauna during the summer for the sake of energy efficiency. They were just as comfortable, if not more, as people living in homes using 80 percent more energy.

Once we got our head wrapped around the Passive House concept of how it could save lots of energy  we were delighted to discover the icing on the cake - healthy indoor air quality and thermal comfort. Now we could see that Passive House would be our secret sauce for our green remodel. We got excited about transforming our old house from energy obese to energy svelte! We loved the idea of an old house with the look and feel of early 20th century architecture having the performance that far exceeds most new construction today. 

Having lived in a Passive House for over 2 years I'm appreciating ​another benefit I've not thought about before:  I don't have to actively do things. Unlike taking out the recycling bin to the curve every week or consciously driving at a speed that optimizes fuel efficiency, I don't have to actively do things to make Passive House work. It goes on saving energy day after day.

Here's an opportunity for you to "get" Passive House. In November 2015 you can learn about Passive House at the Building Carbon Zero California conference on November 13, 2015. Perhaps you'll find Passive House to be the essential first step towards your Net Zero Energy home. It's even better when you can tour many Passive House buildings in Palo Alto on November 14, 2015 to feel the comfort.​ Also, we invite you to see our 93-year-old house performing beautifully as a Passive House on November 15, 2015. 

Do you want to hear stories on how we gathered information and managed the transformation of our 90-year-old house? Sign up for the mailing list to be notified about the Midori Haus tours.

Better Cooking with Gas

October 17, 2015

In the last post I wrote about why it's healthier to cook with electric stove inside the house and keep the gas cooking outside on the kitchen deck. This post is about cooking more efficiently with gas stove.

When natural gas is combined with oxygen and ignited it creates heat and we see the blue flame dancing under the cooking vessel. As the cooking vessel (like the skillet or the pot) heats up it transfers the heat to the content and we cook the food by adjusting the heat intensity by turning the gas knob. So how can we make gas cooking more energy efficient? What if you could cook at the medium heat intensity at the low setting? How about if the pot can absorb and transfer more heat to the food for the same amount of gas burned?

We found a pot that does just that. It's called Turbo Pot and the bottom of the pot has fins that increase the surface area that can absorb heat from the flame. 

Few weeks ago I made a batch of tomato-jalapeño jam using the large harvest from my garden using the Turbo Pot pictured above. I set up my cutting board and the large bowl of tomatoes on the portable table next to the gas stove on the deck. After placing the pot with chopped ginger, onion, and jalapeño I cut the tomatoes as fast as I can and tossed them into the pot. If you're interested in the tomato-jalapeño jam recipe I used this one here.​ It simmered nicely on the lowest gas setting for over 2 hours while the jam reduced down. Had I been using my other stock pot I would have had to use a higher gas setting, maybe a medium instead of the low setting I used with Turbo Pot. 

During the month of September I made couple of batches of tomato-jalapeño ​jam, ketchup, and pasta sauce. (Can you tell I had lots of tomatoes in my back yard?) Each time I used the Turbo Pot for 2-4 hours to at the lowest gas setting. When I looked at my utility bill this turned out to be only 2 therms of gas, which I think is pretty good for all that cooking!

Cooking with Gas Outside for Comfort and Health

October 3, 2015

"Gas appliance outside and electric appliances inside" was the guideline we used for making appliance decision during our remodel. Having both gas appliance and electric appliance made sense for us because Midori Haus was already plumbed with natural gas line for hot water heating. If this infrastructure connection was not in place we probably would not have natural gas appliances.

When we lived in our condo we had a gas barbecue fueled with propane. Although this was a lot more convenient and faster than using charcoal for outdoor barbecue it still required lugging around the propane tank to the service station few times a year to get it refilled. So we took an extra step towards convenience by having a outdoor barbecue unit that can take natural gas as a fuel source and had the gas plumbing line installed. 

At Midori Haus we chose the Weber NG 54488 barbecue unit that has a side burner so we can simmer a large batch of apple sauce or make spaghetti outside and keep the heat out of the house during the hot summer months to prevent the house from overheating. Also the combustion byproducts from gas stays outside so the indoor air quality is better. Plus if there ever was power outage and putting our electric induction cooktop in the kitchen out of commission we can still have a hot meal if the gas service is on. If we truly wanted to be resilient and a bit more self reliant we could even get a solar oven. 

 What's better? Cooking with gas or electricity? It depends on what your decision is based on. I liked cooking with gas because it always felt fast and responsive. My husband used to impress me during our courtship days when he made his speciality dessert of bananas fried with brown sugar and bourbon. He would turn the lights off just before tipping the skillet ever so slightly towards the flame and igniting the bananas for a flashy finale. It wasn't until when I took the indoor air quality classes that I learned the burning that creates heat on the stove top (or gas oven) is a chemical reaction in which  natural gas combines with oxygen. When there is not enough oxygen the combustion is incomplete and produces combustion byproducts. Prolonged exposure to combustion byproducts could cause flu-like symptoms. When we learned about this and appreciated the function of the kitchen vent hood (it wasn't simply to clear away the smell of the food odor) we paid closer attention to how we used the gas stove and our cooking routine at the old condo changed. Our cooking routine started with walking over to the front door to open a window by the stairs (because the kitchen had no windows) then walking back to the kitchen to turn on the vent hood then turning on the gas cooktop. When the cooking was done the reverse routine took place. If this was in the winter the rooms got colder from the outside air and the opposite happened during the summer. We opened the windows to provide a path for make-up-air to come into the house when the kitchen vent hood created negative air pressure. Our little routine to keep healthy indoor air quality had the effect of cooling and warming the indoor space. It was unfortunate that it often happened to be exactly opposite of the thermal comfort we wanted on our skin. 

When we were designing Midori Haus we were really focused on using very little energy to be  healthy and comfortable ​in our home. So we decided not to have any gas combustion appliances inside the house because the house would be practically airtight and we wanted the air to be as clean as possible. This meant the house would have no gas stove top, no gas oven, and no fireplace. Midori Haus is practically airtight, about 10 times tighter than most new homes built today. Having an airtight home saves energy by keeping the indoor temperature constant much longer than a drafty house. We chose not to have the vent hood in the kitchen evacuate the air outside. Instead we got a recirculating vent hood and had the Heat Recovery Ventilator (HRV) manage the ventilation. 

During the late summer months when the abundance of fruits in the garden are begging to be preserved I can choose to cook on the induction cooktop inside the kitchen or on the gas stove outside on the deck. The kitchen can get pretty warm when making jam and sauces. This year I processed my tomato harvest by setting up a table on the kitchen deck and made tomato-jalapeno jam and marinara sauce on the gas stove attached to the barbecue. I spent several hours standing outside cutting, stirring, and simmering the tomatoes on the gas stove, which created lots of heat and combustion byproduct. Even if I was sweating outside in the 90-degree weathers slaving over the jam I smiled knowing that combustion byproducts stayed outside and I can be in the cool comfortable house with clean air just by stepping through the door.