passive house – Page 2

Inching Ever Closer to Rezoning Approval

June 2, 2017 by clove Leave a Comment

We submitted our revised rezoning package March 14 and received comments back from the City last week. We waited longer than we’d hoped for this response, but I’ve come to accept that things taking longer than hoped is standard operating procedure when developing a project.

Granted, we also threw a couple of wrenches into the process by pushing back on two of the City’s requests from the first round:

The City asked us to provide an additional 1.4 m Statutory Right-of-Way in addition to the 1.0 m already required between the property line and the back of the parking stall (see this post for details). In Round 2 of comments, they have removed this request. Phew! As one of our project goals is to preserve as much backyard green space as possible, this is an excellent outcome. We can now move the building closer to the front of the lot as originally intended.
The City had also asked if we were willing to sign a covenant to show we are serious about pursuing Passive House. Initially, we said yes to keep things moving, but then we thought about it some more and talked to a few friends about their painful experiences with covenants, and concluded that we’d be better off avoiding if possible.

A covenant is a legal encumbrance that gets attached to a property and stays there for the life of the property (in some cases), or is there until you have met certain conditions and it can be removed. In our case, the covenant would say that we are designing and building to the Passive House standard and when the city is satisfied that we are indeed building to the standard, then the covenant can be removed. The problem is that both the adding and removing of a covenant means thousands of dollars in legal fees that provide no lasting benefit to the project.

If we weren’t proposing to go well beyond code, we wouldn’t be facing these legal costs. So we are being penalized, not encouraged, for going above and beyond. This didn’t feel right and we believed it wasn’t what the City was going for either, so we wrote a letter suggesting that we instead demonstrate that we have engaged a Passive House Certifier to review and certify the project. This in itself is a several thousand dollar endeavor – but at least it is one that will have a lasting benefit on our project.

The City of Vancouver takes a similar approach. In Vancouver, Passive House is an accepted rezoning path – meaning, to rezone in that city, you have to go better than code minimum, and Passive House is one approved way to get there. No covenants are required, but their code inspectors have the authority to shut down a job site if they find that you are not building to the permitted documents. They also now have several Passive House trained staff, one of whom will be assigned to your project to help you work through the process.

Happily, the City of Victoria appears to be in agreement (or at least not opposed?), and asked us to update our letter to Mayor and Council to reflect this proposed approach.

Next Steps: We now have to update our drawings to remove any reference to the extra Statutory Right-of-Way, respond to a few other minor comments, update our letter to Mayor and Council, and resubmit the whole package.

We think this means that city staff are now preparing their report to the Committee of the Whole, which is a group composed of staff and council and is the last stop before our public hearing. With a little luck we will have an approved rezoning application in hand by mid-summer.

One step closer!

To Passive House or Not to Passive House (Responding to City Comments Part 2)

February 17, 2017 by clove Leave a Comment

The city asked in their first rezoning review if we were willing to sign a covenant to seek Passive House certification. Good question and the time has come to answer it!

There are a couple of good reasons to pursue Passive House certification:

Understanding the nuances of the process by going through it.
Marketability – it’s becoming increasingly recognized and sought out by savvy buyers around here.

Because of what I do for a living, though, I am inclined to remain certification-system-agnostic. If we go for Passive House, it’s because I want to test it out. We’re not doing it because we think it’s the only way to a good building and to a sustainable future. It is a way. Focusing on passive principles, like airtightness, well insulated walls, no thermal bridging, and effective ventilation – is a very straightforward way to dramatically reduce our energy consumption and greenhouse gas emissions, and I do believe this is a critical approach to building better buildings. A house that consumes 20 kWh/m2/yr instead of the 15 required by Passive House at the end of the day is still miles ahead of a typical one that consumes 100.

I’m also very curious about the impact of occupant behavior. Could we build something slightly less than a passive house and use as little energy through conscious consumption? Would we be more uncomfortable? Is there an ideal balance that is something less than Passive House but right in our mild west coast climate? These are difficult questions to answer on a single project, but interesting all the same.

I’ve had in my mind from the beginning what I believed to be a reasonable but very high performing wall assembly: 2×4 wood frame cavity with batt insulation; plywood sheathing, weather barrier, 6” of mineral fibre insulation; rainscreen and cladding. We’re on board for a high-efficiency heat recovery ventilator (Zehnder, Paul or similar) and we’re set on good triple pane windows. We’re committed to renewables with a goal of net zero energy consumption and zero greenhouse gas emissions.

But I was not sure about other pieces like the amount of roof and below slab insulation. And I wasn’t sure how this would all add up in the eyes of Passive House. There was no way of getting around it – I had to model it in PHPP, the Passive House (giant) spreadsheet software.

In early January, I took the 3-day Passive House modeling course as a follow-up to the 5-day design course I took three years ago. I’ve since been chipping away at the model to give us more confidence about what we are prepared to commit to in our re-submission to the city.

I’m relieved to report that I am *almost* finished the model.

The first time going through a whole model for a smaller house takes at least 3 days, assuming you’ve had some training. I’m 24 hours in so far, and this includes a fair bit of head scratching, learning, looking at other examples, going back and fixing mistakes.

I would recommend to anyone who has the luxury to devote 3 whole days in a row to get your head into it; even half days are wonderful. I found two hours at a time is about the minimum to feel productive. And keep moving – if I got stuck and bogged down by something, I moved on to make progress elsewhere, then looped back after I’d had a bit of time to digest the issues, or could ask someone for guidance.

The modeling tool itself is not difficult provided you are comfortable using Excel, but it does take time to understand the intent of each entry and to follow the protocols where they exist. The most frustrating part of the modeling for me was that there are several key entries that require significant work in the background – for example, calculating total floor area, heat loss area, and domestic hot water pipe lengths – but lead to a single number entered into a single excel cell. The progress is significant but can feel small.

Here is the heart of what you get out of the model:

The software is really an energy balancing tool in which your goal is to moderate heat losses (e.g. through your walls and windows), and then balance them with gains (e.g. through people, light bulbs, appliances, as well as solar gains through windows). The remaining imbalance is your heating demand, represented by the red chunk in the ‘gains’ bar above – this is what you have to add to the space, and this is the number that Passive House requires you to keep less than or equal to 15 kWh/m2/year.

I still have a few key inputs to add, but am feeling confident that this is within reach for our project and we are likely to go for it. In the meantime, time to reclaim my personal wellness time and get outside for some fresh pre-spring air! Thanks for reading!

The Path to Decarbonization and Net Zero Energy

October 13, 2016 by clove Leave a Comment

We’re targeting net-zero energy consumption and zero carbon emissions in the operation of our post-project home. Say what?

Net zero energy means that, on an annual basis, we generate as much energy as we use. So unless we have an oil well on our property, we are drastically reducing both our fossil fuel consumption and our utility grid dependence. Zero carbon emissions simply means that we don’t burn any fossil fuels to operate our home.

A home could use one or more different sources of site-generated renewable energy – solar photovoltaics or solar thermal, for example. I’m keeping things simple for the moment by assuming that we will only use solar photovoltaics to generate electricity. Unless we include battery storage, we will still be drawing electricity from the grid when the sun isn’t shining or when our demand is higher than our panels can provide. But in a place like BC that has a net-metering program, we will also be feeding back into the grid when we’re generating more than we need.

So can anyone just plunk a bunch of solar panels on the roof and viola: net zero energy? Not so fast. With the amount of energy most houses use today, you’d need a much bigger roof than you have. Allow me to demonstrate with our existing house.

In an earlier post, I estimated our current annual energy consumption to be about 13,270 kWh per year, or ~120 kWh/m2 of conditioned floor area, based on our first 6 months of utility bills. This is actually an ok number given that we have three chimneys, single pane windows, and all sorts of leaks and drafts. It’s about 45% lower than the average Canadian home and on par with the Germans. We turn things off when we aren’t using them, but we also shiver through the winter with an inadequate heating system.

We now have a full year of electricity consumption data to update my earlier guestimate. Our actual one-year consumption was 13,700 kWh, or 123 kWh/m2/year. The daily consumption curve looks like this:

Full year of energy consumption for our existing house

The ‘curved’ part is the energy we used for heating. If you drew a straight line across the flatter portion of the graph, the area below the line would roughly represent our non-heating energy use, which stays relatively constant throughout the year.

So that’s the energy demand side. Let’s now turn to the solar PV question.

I called up Power to the People, who will do a free, high level evaluation of the solar potential of your house, based on a google earth analysis, some rules of thumb, and an assumption that your roof is not shaded. Here’s what their evaluation spat out for our existing house:

Power to the People Solar PV Analysis

If we covered our south, east, and west roofs with panels, we could generate 7150 kWh annually. This is a little over half of our current consumption. We would have to reduce our consumption by nearly half to achieve our next zero energy vision using only solar PV.

Is this even possible? The Passive House approach promises a 90% reduction in heating demand by focusing primarily on the design of the building envelope. According to my rough estimate, about 50% of our current consumption is for heating. So it would be doable if we both dramatically reduced our heating demand by improving the envelope and found some additional ways to save. I predict, for instance, that my long hot shower habit will be curbed when our house feels warm and comfortable in the winter. We’ve also heard that people who live in passive houses do not use dryers because the heat recovery ventilator helps clothes dry so quickly.

So we think it’s challenging but doable, and our example illustrates two things:

The first step must be to reduce demand through passive strategies, like extra insulation, increased air tightness, and better windows.
The way you live in your house matters too! Turning off lights and electronics, limiting long hot showers and dryer use etc. The lower you can get your energy demand, the more likely you can meet your annual average with site-generated energy.

One of the most exciting prospects about following the passive house approach is that we can reach our goal while feeling WAY more comfortable and having WAY better air quality. Win win!

How Much of an Energy Hog is Our Existing House?

March 18, 2016 by clove 4 Comments

Our goal is to create housing for 2.5 families that uses less energy than the existing single family house. So how much of an energy hog is our existing house?

Here’s what our daily energy consumption looks like for the first 6 months we’ve lived here, starting in July 2015:

So…is this a lot?

Let’s do some very rough comparisons. I’ve doubled our first 6-month consumption to estimate annual consumption; converted to a per square meter metric and then compared against some other references:

Canadian average consumption for a household our size, kWh/square meter/year
Our existing house consumption, estimated, kWh/square meter/year
A typical German house, kWh/square meter/year
The first local certified Passive House (Bernhardt Passive House), kWh/square meter/year*

*We’re just talking ballparks here. It’s pretty difficult to find comparative numbers that all use the same assumptions – my intent is to show a reasonable range in potential consumption.

Hey! We’re actually doing really well by our abysmal Canadian standards, and pretty average by German standards. Of course, we would expect our consumption to be lower than the Canadian average because we have the mildest winter in Canada, although it’s unlikely to result in this much of a difference on its own.

But wait – this is only part of the story.

The other part of the story is that, boy, were we cold over the winter!

Our house came with an oil furnace and an empty tank. We didn’t want to buy a full tank of oil to heat the house for a winter when we’re getting rid of this system with our renovation, nor did we particularly want to use the existing duct work. The previous owner was a smoker and lord knows what might come puffing out of those ducts. Better to let sleeping dogs lie.

Matt cobbled together storm windows for some of our original single pane wood windows, and we put plastic film on the inside of others. And we shivered through the (albeit mild) Victoria winter, with two wall-mounted electric baseboard heaters and 2 plug-in electric heaters. We moved the heaters around depending on what room we were in and closed doors of rooms we weren’t in.

In conclusion, then, our existing house isn’t an energy hog based on the way we’re currently running it, but it surely would be one if we heated to a modern-day standard of comfort.

This comparison shows very clearly the range of what is possible. I think we can hit our target compared to what a typical house in our climate consumes. And I for one am looking forward to experiencing the comfort promised by a well insulated, airtight, and properly ventilated house!

Passive House, Net Zero, or just a Pretty Good House?

August 16, 2015 by clove 2 Comments

Here’s the lowdown on our current favourite approaches to achieve our project’s energy performance goals. We’re more interested in the principles than checking boxes or getting a plaque, and want to pick and choose what will work best for us. (And yes, there are other important goals like low water consumption, healthy and local materials, and creating something beautiful, but today we’re talking energy.)

Passive House
Net Zero House
Pretty Good House

Passive House:

The Passive House standard has 3 key performance requirements:

Annual heating demand <= 15 kWh/M2/year. This is a 70-90% reduction over what most houses use for heating.
Total primary energy demand <= 120 kWh/M2/year (this is a measure of total energy consumption, including the energy required to generate and transport the energy from the source, using a single source energy factor for all of North America)
Air tightness, as Air Changes per Hour (ACH) <= 0.6 ACH50, as measured by a blower door test. This is about 4 times more airtight than a typical new house.

Here’s a snappy video that explains the fundamentals of the Passive House approach:

The basic concept of the Passive House standard is to focus first on the structure itself: highly insulated foundation, exterior walls, roof; airtight enclosure, and high performing windows – and then supplement with mechanical heating and/or cooling systems. So we reduce demand as much as possible first before looking at efficient ways to provide the remaining energy we need. Mechanical ventilation is also required to maintain air quality.

The requirements are performance based (focused on the end result rather than prescribing certain systems or building elements), but they do lead us to certain choices that we must make in order to meet the requirements, such as triple pane windows, very high performing heat recovery ventilators (HRVs), and thermal bridge-free construction. Equipment and windows must also be tested specifically to Passive House specifications, which can limit the available choices of certain products like HRVs.

Passive House does not require site-generated renewable energy, although it does provide a credit toward primary energy demand for on-site solar PV.

Passive House performance is modeled using PHPP, which is a giant spreadsheet that does a lot of backend calculating based on heat loss, heat gains, and local monthly average climate data.

For smaller buildings like ours, we will have difficulty meeting the standard without good unobstructed southern orientation (although there are a couple of new certification options that offer some hope – post to come). The south side yard is especially challenging because butting up against our desire to maximize south-facing windows are perfectly reasonable zoning requirements intended to protect the privacy of our neighbhours. Depending on the distance of the house to the property line, we are limited in the amount of glazing and the rooms in which we can have glazing facing the side yard.

What we do have going for us is a simple shape: both houses will basically be rectangles, which makes the detailing for no thermal bridging and a continuous air barrier much simpler (the less corners the better).

Regardless of whether we meet or seek official Passive House certification, I think the passive approach is common sense for any building anywhere, and this will form the foundation of our design approach.

Net Zero

Net zero energy means that, on an annual average basis, our project produces as much energy as we consume. Net zero carbon emissions means that we either purchase carbon offsets, or we avoid the use of fossil fuel based energy.

Can we produce on-site as much energy as we consume in a year? This will depend on three key things: the design of our enclosure to minimize energy loads, our behaviour as energy consumers, and the amount of solar PV capacity we can fit on the roof. In our case, BC Hydro allows net metering, so we can feed excess generated energy back into the grid, and draw it from the grid when we are in deficit.

Passive House does not require the use of on-site renewable energy, but it makes net zero energy consumption viable because it significantly reduces demand.

We’ll have to do some modeling to look at the solar potential of our roof in our specific location, as well as take a stab at estimating our energy demand to get a better sense of where we’re at.

I think this is a goal worth shooting for. We will design for an all-electric project with solar PV, since BC produces much of its electricity using “carbon-neutral” hydro electricity.

The Pretty Good House

The Pretty Good House is not so much a standard as a practical discussion happening on Green Building Advisor. It’s about making realistic choices based on the best bang for your buck in your climate, and still, by the way, ending up with something way better than code minimum. So not going quite as far as Passive House, but, say, 80% of the way there.

We’ve also seen a big variation in the actual energy consumption of certified Passive Houses, which reminds us of the critical importance of occupant behaviour. How does the impact of behaviour compare with the impact of a well designed home?

I like the Pretty Good House approach – and I would argue that it can lead us to a Really Good House – but it does require a sound understanding of the fundamentals. This is why programs like Passive House are great, because they work as learning tools.

So in summary, we will be applying passive house principles, striving for net zero energy consumption, and hopefully ending up with a couple of Really Good Houses. I am fortunate to work with a bunch of building science geniuses at RDH, who will help us get the details right.

Our project gives us a unique opportunity to compare an existing house retrofit to a new build on the same site, which is very exciting. There is also a new, slightly relaxed Passive House standard that was just released, designed for small houses on constrained lots like ours, so that might prove a viable option for us.

We will document our before and after energy consumption and share the results here. Stay tuned!

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