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

We finally have bids on several options for mechanical systems…everything ranging from in-floor radiant to forced air.  We probably won’t choose one for a little while, but at least we have the information.  Here goes:

Option 1 – Hydronic Radiant  $45,400:

$17,320 = tubes, manifolds, thermostats and tankless water heater

$22,000 = warmbard material only

$3,300 = A.O. Smith Vortex high efficiency water heater for domestic water

$2,870 = Lifebreath HRV installed

This includes in-floor hydronic radian system in warmboard.  Due to weight, we cannot use gypcrete.  We did consider some less technical installation methods, such as stapling the hydronic tubes to the underside of the flooring, but in our case, we think the decreased inefficiency isn’t worth it.  This does not include any cooling if it should be needed in the future, nor a means to easily add cooling

Option 2 – Mini-split ductless heat pump $32,550:

$26,380 = Fujitsu 3 heat pumps, and 9 interior fan coils

$3,300 = A.O. Smith Vortex high efficiency water heater for domestic water

$2,870 = Lifebreath HRV installed

This is the most efficient system we have priced out.  On the plus side, it’s efficient, doesn’t use ducts and can heat and cool.  On the negative side, we have fan coils to look at (even though a couple of them are concealed), and during the very coldest and hottest extremes, the system may have a hard time keeping up.  The higher price may be justifiable with the energy efficiency over time, especially if we can incorporate solar.

Option 3 – Unico high velocity system w/mini split ductless for the ADU $29,175:

$25,875 = Unico high velocity running off SEER 13 heat pump by Ruud, Daikin mini-split pump w/2 fan coils, HRV

$3,300 = A.O. Smith Vortex high efficiency water heater for domestic water

So far, this option feels the most appealing.  We have both heating and cooling.  The design of the house won’t be compromised by ducts.  The ADU gets it’s own efficient heat pump and the high velocity system is extremely quite and feels much more comfortable than traditional forced air.

Option 4 – Traditional forced air $23,960:

$20,660 = gas furnace, standard programable thermostats, HRV and air filter for the HRV

$3,300 = A.O. Smith Vortex high efficiency water heater for domestic water

While this is a much less expensive options, there are two major drawbacks.  Firstly, we haven’t designed the house with soffits for venting, nor do we want to change the design to accommodate them.  Secondly, it’s forced air which is not what we were hoping for.  This does not include cooling, but an AC unit can easily be added in the future.

All of these options also include the necessary bath/laundry/kitchen venting and gas hook ups.  We have a lot of time to decide which system we’ll go with, but please feel free to add comments on what you think is best.  I’ve learned when it comes to the mechanical system, there is hardly ever a ‘golden’ answer…usually a few good choices and a few bad choices.