Hill House

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.

If you’ve been following this blog, you know that we have received a grant from the City of Portland for our eco roof.  All three levels of the house have their own eco roofs in addition to the main roof.  We met today with our very talented landscape architecture firm, 2.ink Studio. They are a great fit for us as they are open to doing something that is out of the ordinary – maybe something that hasn’t been done before – and their graphic eye to modern design works well with our aesthetics.

Our roof is completely visible from our neighbors deck behind our lot.  They’ve expressed concern with what they’ll be looking at visually.  Because of the visibility factor, we really want to do something out of the box that is visually stunning, but still performs the functions of a typical eco-roof.  2.ink Studio has done a great first round pass at design and we’re really excited to hopefully have something electronic to post after we meet with them next.

Also – to follow up on the HVAC design.  The reality of a forced air system seems to be looming over us.  To aid in our informative decision process, we’ve decided to also get pricing on a Unico high velocity forced air system.  I’ve used this system in the past and it works great for modern architecture where duct runs can potentially alter design.  The system relies on a main trunk duct with multiple 2″ flexible ducts extending from the trunk.  This allows for installations without the need to drop soffits for ducting.  It also blows much more quietly and efficiently than a traditional ducted system, plus it can run off a heat pump, electric furnace, or can be coupled with your domestic hot water of all things.  I’ll keep you posted on all bids when I have them in hand.

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 – we’re still working on our exact foundation method.  We have one particular wall that is holding us up, but we are making progress.  Meanwhile, we’re working to nail down our mechanical systems.  We’re set on radiant hydronic heat.  We’re installing PEX tubes into Warmboard sub floor.  This leaves us to consider a way to heat this water.  We have 3 basic options.  1. solar thermal, 2. geothermal and 3. a heater.  At the moment, geothermal may be out of our reach considering the cost of actually building the foundation for this house.  The 30% limitless tax incentive is certainly nice, but still does not bring this option in our overall project budget.  Solar thermal still might be an option, but additional heating will still be needed so we’re left with a heater.  There are several options for water heaters – both tank, tankless and electric and gas.  At this point, a commercial tankless gas heater by Navien seems to be the winner.  The Navien system is 98% percent efficient, doesn’t have a minimum water output and actually has a small internal tank that preheats water to avoid the cold wate surge that is common among other systems.  The plan at this point is to use solar thermal heating for domestic use.  We’ll probably have a large tank, or maybe two tanks.  We’ll supplement this system with the Navien unit to help out when needed.  We were hoping to avoid using any fossil fuels at all, but there simply aren’t many great options out at the moment that are electric.  Luckily, we can replace a gas unit with an electric unit in the future should things change.

Honestly, this should just about do it for mechanical systems.  Due to the house being built into the hill, we don’t feel there will be a great deal of direct heat gain in the summer.  Virtually all the glazing is on the north side of the house.  The roof will have a White TPO roof membrane with a high solar reflectance, but will at some point be covered with a planted roof, so heat gain from the roof should be kept to a minimum.

We may plan on roughing in a heat pump system for future install just in case.  With global warming and climate change happening, I think it’s reasonable to assume our environment here in Portland may be diffrent in the next 20 years – if even a couple degrees.

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.