Hill House

If you’ve been following along, you’ll know we were lucky enough to get a grant from the City of Portland.  This is indeed a great thing.  Green roofs have many benefits – here is a brief explanation from the City of Portland web site:

“Ecoroofs replace conventional roofing with a living, breathing vegetated roof system. An ecoroof consists of a layer of vegetation over a growing medium on top of a synthetic, waterproof membrane. An ecoroof significantly decreases stormwater runoff, saves energy, reduces pollution and erosion, and helps preserve  fish habitat.

Ecoroofs also absorb carbon dioxide, cool urban heat islands, and filter air pollutants. Ecoroofs increase habitat for birds and insects and provide much needed greenspace for urban dwellers.”

In keeping with our general gravitational pull to try to do something different and ultimately more interesting than the ‘norm’, we new we needed the right team to help us figure this out.  Green roofs are extremely tricky to install successfully when you add into the equation weight restrictions and limited soil depths.  Basically, we have tundra conditions less than 500 fee above sea level – not to mention complete drought in the summer for 3 months.  When we were awarded the grant, we knew exactly who to work with.  2.ink studio is more than willing to take a chance with us.  They have a great eye for conceptual design and the fit so far has been perfect.  I have attached some images below from our first presentation meeting with them.  They developed a series of conceptual ideas breaking out the 3 green roof decks we have on floors 2 through 4.  These decks are all North facing and will see little, if any lighting.  This image shows a layered approach, with ferns around the perimeter with miniature hastas and smaller mexican grasses.  To add a layer of contrast and to flex the brightness of the colors, 2.ink inserted rows of small basalt blocks.

conceptual idea of roof deck

The roof itself is both technically and conceptually different.  Technically, it will get sun and during the 2-3 months in the middle of the summer when we don’t have rain, it will need to be watered.  Our plan is to use a gray water system sized to allow us to sprinkler irrigate the roof all year as needed with recycled water.  Because the roof is visible from neighbors behind us, and because we’ll be using it as outdoor space, we really wanted to push the design in a direction that is flexible, rhythmically interesting and graphic.  There were 4 conceptual options we looked into, but this one, with it’s undulating plan and colors seemed like the best fit.

conceptual plan for green roof

Another component to consider with the green roof is the plant species and how those species behave throughout the year.  Ideally, you’d want 50% or more evergreen so you have some coverage during the winter.  2.ink developed a calendar that shows what species thrive during specific times during the year.  For someone who is visual by nature, this is an excellent tool for us.  This file is a little difficult to read, but you get the idea.  At the moment, these concepts are being detailed further  to the point of construction drawings.

calendar of plant activity

Working through all the bids and negotiating with subs has certainly taken some time.  On top of this, our checksheets from the City of Portland for Structural and Soils were fairly lengthy.  The architectural set of drawings referred to the structural set in many cases.  The structural set then referenced the Geotechnical Engineer’s report.  The City didn’t like this at all.  They wanted all the Geotechnical information shown in the drawing set.  Their argument is they don’t think a sub contractor would look in a report.  Maybe slightly picky, but makes sense.  We ended up making a new set of ‘Geotechnical’ drawings to add into our overall set….should work.  We’ll submit them next week and see what happens.

In the mean time, we’ve been looking into the multitude of heating and cooling options.  To get into some basic costs, the Warmboard floor sheathing we have specified in the house runs $22,000 (typical plywood sheathing is $3,000).  This price includes a ‘trade’ discount, which is nice.  On top of this, we have a radiant system that will run $15,000 – $20,000 for pumps, tubes and manifolds, plus water heating equipment (boiler, tankless or tank heater) at another $2,000 – $6,000 depending on the equipment.  On top of this, we have very minimal insulation bids at $25,000 for full perimeter 1 1/2″ flash and batt to $35,000 for 3″ flash and batt.  Flash and batt refers to a ‘flash’ pass of spray foam, followed by a less expensive batt or blown in insulation for the remainder of the wall cavity.  My theory has always been to spend your money on a tight, well insulated building envelope and spend less on smaller, more efficient HVAC equipment that will use less energy during the life of the building.  Keep in mind, we are building 8″ thick walls and 12″ deep roof diaphragm that needs to be completely filled with insulation.  I did stray from my theory towards a more expensive and luxurious heating system that may cost up to $48,000 to install.  In addition, because you don’t turn a radiant system off, you’re wasting energy while you’re away from the house during the day.  A humbling exercise.  We have determined our radiant system to be a fantastically wonderful luxury.

At the moment, we are getting bids on three systems:

1. hydronic radiant heat with a gas fired AO Smith Vertex water heater and another for domestic water

2. Fujitsu mini split ductless heat pump for heat / cooling, Vertex water heater for domestic water

3. Fujitsu split ducted heat pump for heat / cooling, Vortex water heater for domestic water.

Why not a tankless water heater?  With the addition of the ADU in the building, we have a potential of 3 showers and 2 dishwashers running at the same time.  This load if fairly difficult for even the best tankless to keep up with.  Using a dishwasher with an internal water heater can help, but three showers at once is still tough to manage.  We’re working with EcoHeat on pricing.  We’ve found them to be extremely professional, knowledgeable and competitively priced.

Well – not totally free, but we received word yesterday that we were awarded the total grant amount available for ecoroof’s of $5 per s.f.  This funding is available to subsidize the cost of design and installation of ecoroofs in Portland.  Not only did we receive full funding for our house, but two other projects we are working on, 14 house and Twigg residence both received full funding as well.  Our three projects represented 10% of the total applicants.

We had a meeting yesterday with our HVAC sub, Ecoheat.  The owner, Thomas Schwab is passionate about not only quality installation, but sustainable systems as well.  Early on in our project, we decided to use Warmboard as our floor sheathing.  The main reason honestly, is that we weren’t able to make concrete slab floors work from a structural standpoint.  But as we looked at other options for radiant heating, Warmboard stood out as a clear solution.  The product heats up much quicker than thermal mass systems, such as concrete or gyp-crete.  It also needs less heat, which means it takes less energy to maintain a comfortable temperature.  

We also decided early on in our process that solar hot water would be a given.  As it stands today, we’re looking at a handful of options.  1. solar domestic hot water w/ either a gas fired boiler, or electric boiler for the radiant system.  2. alternative heat source to be a heat pump, or electric wall heaters.  3. geothermal heat for both domestic and radiant heat.  4. possible at source on demand water heaters in the kitchen to reduce water usage.  Due to the lack of direct solar access, we don’t feel Photovoltaics will work for electricity, so we’re looking to be more creative.  We’re still entertaining the idea of no gas lines to the house in an effort to not use non-renewable resources.