Habitat House Part 2 – The Energy Audit
This is the second post in a series about a Deep Energy Retrofit (DER) on a Habitat for Humanity house in Ravenna Ohio. This post focuses on the energy audit of the home. The first post focused on the principles we use and the priorities/budget for the project. The purpose of this series is to transparently show the process of the planning, upgrades, and client feedback from this project.
A Deep Energy Retrofit, as defined by Linda Wigington, is any upgrade that reduces energy use by more than 70%. The modeled energy savings on this project are 72-77%. This is pretty exciting for us. It’s a hard thing to do, particularly on a tight budget.
Now that we have client priorities, and a working budget, it’s time to look at the house and see what it needs. After this we begin the design charrette to see what best meets priorities, budget, and house needs. This is our planning process.
The Energy Audit
An energy audit sounds like something the IRS would do. It’s not. It’s a holistic look at a home based on 4 priorities: comfort, health, durability, and efficiency. Exactly what it entails varies from house to house and client priorities.
Normally this is a full scale energy audit, but in this case the house has been gutted and the furnace and water heater disconnected. Oh, and the electricity has been cut. This reduces how much can happen at this step.
Typically I do the audit on my own. This is my best opportunity to commune with and get to know the house. After being in a house a while it may start to tell me things. This not mystical, remember I have spent a fair amount of time discussing concerns with the occupants, so dots start connecting.
Walking around the house I take measurements and pictures while thinking about and looking for root causes to problems I was told about. I take a ton of pictures, which often expose problems later and help us develop and understand reasonableness of work scope. You simply can’t know in advance how important a picture of a specific part of the house can be for understanding what’s possible. If we decide to change approaches, a picture may tell us if it’s possible without having to go back to the house.
In this case the house is gutted with no power. This is also my first meeting with Scott Craven, Habitat of Portage’s project manager, so I was unlikely to be alone for this audit. Normally our process has two site visits – this is intentional – we want to get comfortable with the client and their home and we’ve found one visit doesn’t serve this high priority objective.
But this project has a tight timeline and Scott is quite experienced in construction. His expertise lies in new construction while mine lies in retrofits. All these factors allow this project to comfortably follow a more accelerated timeline. Our skills seem nicely complementary, which make our discussion a lot of fun. We bounced a ton of ideas around and began the ‘design charrette’. The first iteration of our plan started to come together. He’s willing to push boundaries, so we get to stretch our design approach a bit. We’re both thankful Rachel Kerns, the executive director, is on board as well!
Background on the House
How Habitat of Portage came to acquire this house is an interesting story with a sad side. Originally, the client for the home was a disabled woman who wanted a small home with an open floorplan in Ravenna, Ohio. An existing home was sought. Because she was disabled, the structure of the house needed to be capable of having doorways widened. This severely reduced the number of possibilities, and after Rachel Kern looked through about 15 properties, this one was chosen. Sadly, the client suddenly passed away at a young age. The house may not have been ideal for other purposes, but this was why it was chosen. A new client was discovered, a mother and her 17 year old son.
Initial Observations
We believe the original part of the house is a 14×22 box. Bedrooms were added on the right side and a lean to structure was put on the back for the kitchen and bathroom. Rough scale drawings on graph paper are part of every audit, below is my rudimentary drawing of the attic. Each box is 2’ x 2’ to scale. Note: this is not a blueprint, just an initial vision for the project. In fact, plans have already changed several times since this drawing.
Judging by the gas lines for gas lights, the first part of this home dates to between 1890 and 1910 which disagrees with the county records that say 1940. Apparently there was a fire in the county records office about that time.
Harry Potter Tent
Since the interior had been gutted it laid bare the opportunity for the original part of the house to have a 13 foot cathedralized ceiling, which will make a small space much more interesting and pleasant. Below is a view above the rafters and then a view from the front door. The Property Brothers would call it open concept.
The house looks tiny from the outside, but when you walk in with the very high ceiling, it feels HUGE. It reminded me of the tents in Harry Potter which looked small but lived like a house inside.
Scott and I both feel a cathedral design should be explored. If we can make it particularly pretty and unique it’ll be much nicer for the homeowner and more suitable for public relations to show what is possible when you are willing to stretch thinking beyond the box. Naturally, this won’t be possible for most Habitat homes, but makes for an interesting case study.
Now I have to figure out how to make a Harry Potter tent out of this 720 square foot ranch. It’s called a ‘jewel box’ treatment: making small homes live large. Normally this is very difficult within a Habitat for Humanity budget, in the case of this particular house, it just might work. We both started giggling like eight year old girls thinking about how cool it could be. This is just the kind of project we both enjoy – fun and pushing the boundaries a bit.
The next day, Scott did a little hunting and texted me this picture for inspiration of how the room could look. (Sadly, I don’t have attribution for the pic, if it’s yours, please speak up!)
After the giggling stopped, we discussed the priorities and budget items from the last article. Then it was time to puzzle through the house using the 4 Priorities, partly with Scott, and partly on my own.
Here’s what we found:
Comfort
This house was leaky before. After being gutted it makes a sieve look tight! Part of every job is measuring air leakage which we do with a blower door:
For reference, I consider a house decent when it has a blower door leakage number roughly equal to its square footage. This house is 720 square feet plus 1/4 basement, 3/4 crawl. If it was a normal project I’d like a target in the 700 range (that’s a back of napkin B or B- for leakage.) Houses are pretty bad when their leakage is double square footage (2:1). At 3:1 it’s horrific. Here’s how this one started:
Yeah, at 12,000 or 16.7:1, we have some work to do. Keep in mind it’s gutted, so we’re pulling from everywhere – leaks in the walls, roof vents, exterior basement stairway, etc. My guess is the real number was closer to 2500, which is still abysmal. There’s a reason older homes are known as drafty.
Lots of air leakage generally translates to a very uncomfortable house because outside air leaks in all over the place. Tighter homes are much easier to control because it is much harder for outside air to come in and turn your feet to ice cubes. (Check out my article on blower door readings to understand more.)
Anyway, this initial leakage number is so high that it’s impossible to understand where it’s coming from and practically meaningless, but at least it’s a starting point. Now to set some leakage goals. I have chosen the extremely difficult Passive House standard as my target for leakage. So my target is 110 cfm50 down from 12,000.
Next we headed for the basement. It’s actually a cellar with a 6’ ceiling, and only in about ¼ of the house. The furnace and water heater lived there, key parts of the comfort equation. The furnace and water heater had seen better days. They’re red tagged, meaning they were shut off by the gas company because they are hazardous. That’s ok, we plan to go all electric, so a gas water heater and furnace is not an ideal fit.
Before we continue, remember this home was purchased for its floorplan, not the basement.
The ductwork was literally falling apart. There was a lot of saran wrap on duct leaks, indicating previous uncomfortable occupants making a desperate attempt to send heat to the house rather than dumping it in the basement.
I didn’t get a good picture of it inside, but there were a lot of gaps in the foundation you could see light through. This tells me the basement and crawlspace are wildly leaky. These need to be addressed for both air and water leakage. Here’s a picture from the outside, note the missing mortar in a few vertical joints. This condition exists everywhere.
After my inspection, I could easily tell that the comfort in this house was eclipsed by many a barn or corn crib. Normally I have feedback from the clients on this to understand which rooms experience poor comfort and when, in this case evidence poignantly replaces words.
Health
Bill Rose, who wrote the wonderful book Water in Buildings told the story on IAQ Radio of how he became a home inspector as a research tool to understand how many homes had mold in the attic and why. He found that every single home with a dirt crawlspace had mold in the attic.
Let’s apply that to this house:
Yep. That’s a dirt crawlspace. It’s under ¾ of the house. The other quarter, the cellar, has a little concrete but is not very dry. So now let’s check under the roof.
Sadly, most of the roof deck is covered with mold. Even some of the old wood, which is more mold resistant. This is certainly a solvable issue, however it complicates the solution package somewhat.
The damp crawlspace and rough roof deck are health and durability issues. A damp building with rotting roof deck. Damp buildings were causally connected to childhood asthma in 2015. That’s a big deal. Even scientists don’t have a good grasp on exactly why wet buildings are bad, we just know they are. Moisture management is something that has to be dealt with by any plan we devise. While this house has above average issues because of the crawlspace, moisture problems are shockingly common. We ALWAYS consider moisture management in our designs.
Once the house is tightened, moisture is more likely to stay inside because it can’t leak outside anymore through cracks. High humidity is bad for a number of reasons, I wrote about it here. With the ridiculously low leakage target I set, moisture control could be a 12 month issue. We will automate humidity management and plan to have monitoring of both humidity and indoor air quality because of the desired tightness of this house. Foobot has already stepped up with a free Indoor Air Quality monitor for dust and chemicals. Moisture and IAQ are pretty good sized complications which we’ll talk about in the next article. (We also include IAQ solutions in every set of plans we create, typically in more costly packages.)
Durability
Water kills buildings. I am always on the lookout for water problems. Liquid water is the biggest concern, followed by water in vapor.
The biggest thing to look for is drainage: does the ground slope away from the house so water wants to go somewhere else? Do the drains get at least 6 feet away from the house? In the case of this house, we’re in good shape. All the drains get away from the house and the house is at the top of a small hill.
Note how the drain gets behind the house and how it goes downhill. This is good. The other drains were the same way.
The holes in the foundation I mentioned are a big concern, but one that’s hopefully easily resolved. They’ll need to be tuckpointed and we’ll need to find a way to deal with the moisture inside the basement and crawlspace. The liquid water that gets into the crawlspace turns to vapor as it warms up. Moisture in the air is lighter than the air itself, so it tends to rise, so after evaporating it heads for the attic carried by air through plentiful air leakage pathways. If attic surfaces are below dew point temperatures (like a snow covered roof) the moisture condenses back to liquid, feeding mold and rotting the roof.
This house likely got some serious icicles and ice dams which can also provide water to rot the roof, leak water onto ceilings, and cause other moisture problems.
Nothing about this project seems to be easy. Our audit uncovered two major roof leaks. Check out the sheathing here, it’s above the original bathtub:
Black is bad. You don’t want to walk above this unless you are in a real hurry to see the basement. The house needs a new roof to deal with all of this rotted sheathing and the roof leaks. Thankfully, enough donated roofing material is available for replacing this roof.
In the very tight house that we’re going to create, even small amounts of water vapor can become a problem. We humans breathe moisture out. We perspire. We cook. We shower. All of these add moisture to a house that doesn’t have a way to deal with it unless we plan it in. So again, we’ll need to have a plan for managing water vapor in the completed project.
Because I frequently work on homes with moisture problems I’ve become sensitized to them. After spending the day in this house I had a bad headache and was feeling a bit foggy. It could have been not eating or drinking enough, but judging by all the mold and moisture in this house, I expect moisture was the cause of my symptoms.
There are several substantial durability and health issues to deal with, these two are usually closely related. Again, it makes the solution design tricky, but not impossible.
Efficiency
The last of the 4 Priorities is efficiency. Usually if you do a good job tackling the other three, efficiency shows up in spades. Air seal and insulate so the house easily stays warm or cool. Make clients really comfy so they forget about their HVAC (furnace/ac/heat pump/etc.) Good things happen to energy bills. A comfortable and efficient home is as airtight as possible, has good insulation, and has an efficient HVAC system. This needs to include fresh, filtered air being pumped in as well for any home, but particularly tighter ones.
This house is a blank canvas since it’s gutted. We modeled two approaches. One was three times more attractive on a key metric. That’s for discussion in the next article on the planning process.
Conclusion
Here’s the gist of what we found during the energy audit.
- Lots of moisture problems to deal with
- A blank canvas for insulation and HVAC
- It can feel like a Harry Potter tent if we insulate the roofline
- A jewel box opportunity if we insulate the roofline and create a loft
- Potential to get to a very low leakage level
I view this project as one of the most fun and challenging projects my partner and I have been faced with. Now that Scott and I have looked over the house and bounced ideas off of each other, it’s time to dig into the planning process which includes an energy model to help us make decisions rationally and not emotionally.
This is where the iteration begins – how about this? Or that? How does it affect performance? Can it fit in budget? Can we get a discount because it’s Habitat? Because a lot of labor is volunteer, we have to stretch our thinking. Everything about this project breaks the mold.
We’ve lone-wolfed it to this point because of a very tight deadline: Women Build Week, sponsored by Lowe’s, is April 30th – May 8th. Saturday May 7th is hoped to be a major push forward on this house. As much as possible needs to be lined up so volunteers have as much as possible to work on, rain or shine. (Click here to volunteer!) It’s time to loop the rest of the team in, share what we’ve been working on, and hopefully build consensus.
If there’s one thing I’ve learned, I seldom know what’s going to come out of the other side of the planning process. This serves to keep me humble and cautious about “shortcuts”. After my partner and I develop our comprehensive plans with what we think are the best paths, I take them to the client who usually changes it a bunch more. It involves a lot of teamwork where I’m player and coach. The whole time I do my best to stay open and roll with the punches while keeping priorities and budgets in mind.
Once again, I’d like to thank Habitat of Portage for this delightful opportunity to try some new things and for the faith they have in making this fascinating project work.
In the next article in the series, I’ll explore the planning process my partner and I go through to come up with packages for deciding how to fix a house. Then we’ll cover Scott and I’s meeting to narrow in and looping the rest of the team in.
My hope is to call this a true Deep Energy Retrofit, which requires 70%+ energy use reduction. Can we do it? Stay tuned!
Further Reading
Habitat Deep Energy Retrofit Part 1 – Principles, Priorities, and Budget
Photo Album – Here’s the photo album for this project. I add to it as the project goes on, so come back periodically to check progress.
What Does a Blower Door Reading Mean? – My article on the subject.
Humidity and Its Effects – Not a super fun subject, to be sure, but an important one. Too high and too low are both bad. They have major effects on the health of homeowners and the longevity of the home.
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