Chapter 14 - A report card on our smart house

It's hard to believe that 6+ months have elapsed since my last post, but the passage of time allows me to provide some longitudinal data on the energy performance of our green (r)evolution Huf Haus.

As we had projected, our solar array has generated a significant electricity surplus:

We have generated approximately 20,000 kWh of solar power.  Although our utilization is increasing as expected, we have accumulated a net of -8,000 kWh.  This has resulted in a significant credit on our statements from West Penn ($355.34), our electrical utility; we haven't paid an electricity bill since our net meter was installed.  They deduct a "customer distribution charge" of $5.00 each month. As described on our monthly bills, this is a fixed charge for meter reading, billing, surface line maintenance and equipment.

Our biggest energy concern last fall was whether our high tech balanced ventilation system by Zehnder of the Netherlands (http://www.zehnder.nl/producten-en-systemen/comfortabele-ventilatie) would keep our house cool in the summer.

In lieu of air conditioning, our home has a Zehnder ComfoAir heat recovery unit and a Zehnder ComfoCool unit to regulate the temperature and humidity of the fresh air. The ventilation system consists of the ComfoAir unit, a duct system for supply of outdoor air and exhaust of indoor air, supply and exhaust valves.  These were seamlessly incorporated into our build out.

Ceiling exhaust (left) and floor intake (right)

Because of our impressive home insulation, our breathing generates significant carbon dioxide in our home When set on automatic, a CO2 sensor which is a component of the system will control the ventilation setting; it looks like this:

We can also track CO2 and humidity via our Domovea server.  The data looks like this:

There are two key differences between air conditioning and our ventilation system.  Air conditioners recirculate air but do not provide ventilation.  Our ComfoCool system supplies outdoor air.  Air conditioners only work in the rooms in which they are located.  The ComfoCool system cools air throughout out home.  The system is controlled using a operating panel:  The panel looks like this:

We typically set it like this when we are at the house:

And like this when we are away:

The real question is whether this is working.  And the answer is yes.  We weren't concerned about our geothermal heat pump keeping the house warm in the winter but we were dubious that the house would be comfortable in the summer months without air conditioning.  And we were wrong.  Here is a summary of interior and exterior temperature for May 2014 to May 2015:

This graph is busy but important showing the temperature on the y-axis and both our rooftop temperature (via our weather station which is described in a previous post) and the temperature in the center of our home (the dining room).   There is a gap due to some inexplicably lost data, but in spite of some significant fluctuations in outdoor temperature our home has remained very close to 23 degrees Centigrade = 73.4 degrees Fahrenheit and very comfortable.  The system is almost silent (our plant room is highly sound-proof) and even though the house has multiple glass panels, the circulation of air is imperceptible.  This really is a very smart house.

Our only other major addition since my last post has been the purchase of a tractor to begin preparing our old hay field for planting of either a wildflower mix or switch grass.

We really love the house.  But even more than the house we love the view.  Two weekends ago, we got an terrific look (not well captured on film because of our shock) of an adult male harrier:

Who knows what next weekend will bring?

Chapter 13 - Underfloor cooling 101

For the past two months since my last post, Steve has been trouble-shooting an important component of our home energy plan - underfloor cooling.  This was a component that hadn't been tested during our handoff which occurred during a cool month of the year.

Our plant room contained all the necessary components for the required warming of the brine from the geothermal pump:

But it was clear there was something wrong in terms of the relay between the pump and the heat exchanger responsible for warming the brine to the lowest temperature which would avert condensation under the floor.

Steve was able to provide some detailed data demonstrating the problem which was relayed back to redblue Energy (http://www.redblue-energy.com/home) who then communicated with our local electrician from MEC:



The system is managed using the Exigo platform (http://www.exigo.com/services/) from Regin (http://www.regincontrols.com/en-GB/home/) which is an international company specializing in indoor comfort solutions.

With a lot of communication and cooperation between Matt Radaker from MEC (http://mec-electrical.com/) and Stefan from redblue Energy in Muschenbach Germany via teleconference, the troublesome relay switches were identified and corrected and some valves were adjusted and now we have seamless switching from underfloor heating and cooling.  It's working!  And, we can monitor it remotely using an IP address on our home intranet.  For example, right now, the system looks like this:

Looking a little closer, this is the current status of our heat pump and heat circuit:



This may not reproduce well, but we also obtained the schematic of our entire home energy plan:



which I am including to demonstrate the incredible expertise of and support from redblue Energy. 

We are thrilled to have all of the energy systems in working order and have enjoyed our very comfortably cool and low humidity home through the end of summer.  The system won't be really challenged again until next summer.

We have had two major disappointments over the past two months.  The first is, that in spite of herculean efforts on the part of our financial manager at Morgan Stanley 

(http://www.morganstanley.com/), we were unable to secure any type of home equity loan on our home. We went through multiple failed attempts to get it appraised all of which were denied because there are no comparables.  We wanted a one-of-kind home and now we have one which precludes any type of appraisal which is mandatory for a loan. The other disappointment relates to a flat out rejection by Dwell magazine (http://www.dwell.com/magazine)

for my project submission.  One of the editors told me that this house is definitely not what they are looking for in their publication.  This is ironic because the magazine has literally been the mental inspiration of this project since its outset.  The Dwell website recently featured the Honda Smart Home US (http://www.hondasmarthome.com/tagged/heatingandcooling)

which has many features similar to ours and makes us envious about photovoltaic battery storage, which we may pursue at some point when we live in Bedford PA full time.

The Dwell editorial staff may not love our home, but we certainly do.



Chapter 12 - Keeping cool

Looking back, one of the most memorable days of our green home building journey occurred during our Site Visit on January 29, 2012.  That was the day Torsten Schneider, technical manager of redblue energy, our home technology firm, advised us to have our home engineered with passive cooling as opposed to active cooling, otherwise known as the ubiquitous type of air conditioning found in most US homes.

In a series of e-mails explaining our options, he recommended that our house be cooled in the summer months using our ground source heat pump integrated with our under floor heating system and a ventilation unit with an adapted refrigeration system.  He described this approach as innovative which clinched it for us, as we were on a quest for a one-of-a-kind green home. 

That decision was made in the middle of winter.  Now at the end of June 2014, you may be wondering:  how is that working out?

For one thing, the integrated system is a complicated one.  Here is another shot of our Plant Room:

 

From right to left, this photo includes our Bosch geothermal heat pump, our very high tech hot water tank (hot water and buffer), our stacked ventilation systems and the under floor heating system.   This photo shows the modification of our heat pump outflow to accommodate the diversion of refrigerant for under floor cooling: 

 

 

At some point before the hand-off, the key pumps and valves in this system were to have been labeled  We recently found these labels and are going to coordinate with redblue energy on their proper location:

 

 

 

 

 

The diversion of refrigerant is accomplished by one of two high efficiency circulators from Wilo USA (http://www.wilo-usa.com/wilo-usa-llc-home/wilo-usa/); here is a close up image:

 

Their website includes information on the pressure and temperature readings that activate the circulation:

 

Via a series of high tech valves, one circulator diverts refrigerant from the geothermal loop pump modules which are manufactured by Geo-Flo (http://geo-flo.com/)

 

 

One significant practical limitation of this approach is the fact that the refrigerant temperature from the geothermal wells is actually too cool to be diverted directly to the under floor heating pipes because of condensation.  It actually requires some type of heat exchange which remains a mystery for us.  This will be investigated and explained in a future post.

 

The second major component of our cooling is our Zehnder ComfoCool 350 (http://www.zehnder.co.uk/comfosystems/):

 

This is a combination of a heat exchanger and dehumidifier.  It also has significant limitations in terms of the heat exchange, but is highly efficient in terms of maintaining continuously low levels of humidity in the house (around 40%).   We monitor all of our in-home settings with our new Dell Venue tablet (http://www.dell.com/us/p/dell-venue-8-pro/):

 

 

This is a compromise we use to access our home automation software (Domovea Client) via Windows because to date there is no Android or iPad app for Domovea available in the US. 

 

It turns out that the house has actually felt comfortable in spite of interior temperatures as high as 80F and outdoor temperatures as high as 95F.  We are still experimenting with the ComfoCool and under floor heating settings and have been communicating with redblue energy to learn how to keep the house as cool as possible this summer. 

 

Learning about the energy systems has created a steep learning curve for me.  We never had a comprehensive software analysis of the cooling system done before the house was built (although redblue energy did one for an even higher tech green(r)evolution Huf Haus in Cologne, Germany with more information in German language at http://www.huf-haus.com/de/home).  This is what that Plant Room looks like:

 

 

 From my relatively energy-naïve viewpoint, it's really all about our amazing shutters, with more to come about them in a subsequent post. 

 

Earlier this month, we decided to put minimize our carbon footprint even further and bought a Chevrolet 2014 Volt (http://www.chevrolet.com/volt-electric-car):

 

 

and a Leviton (http://www.leviton.com) fast charger:

 

 

 

 

 

We decided to go with the Volt after looking into other alternatives because of our long driving distance to the Huf Haus (111 miles).  We are averaging approximately 80 mpg. We have a Volt-compatible bike rack on order so we can continue to explore the C & O Canal trail and the Western Maryland Rail Trail which are accessible approximately 16 and 24 miles from the house (all on battery with the latter at full range).  This is me at Fifteen Mile Creek Aqueduct this weekend

 

 

where along the well shaded cool trail all I needed to do was look out for Eastern box turtles

 

 

 





Chapter 11 - Home sweet complicated home

For the past two months, Steve and I have spent most of our weekends in our new home:

We have been tracking our West Penn net meter which tracks the kWh we are transferring to the grid and what we are utilizing from the grid.  Here is a graph of our current energy surplus: 

 

 

We have had some home furnishings delivered from Room & Board.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

We also had to make our first service call to Morrison Geothermal. 

Several weeks ago, Steve noticed some minor leakage of the bluish tinged refrigerant from our TW series water-to-water (ground source) Bosch heat pump (http://www.bosch-climate.us/products-bosch-thermotechnology/geothermal-heat-pumps/). The technician was able to identify a leak in the one of the load side connections and promptly repaired it. 

We have also had some consternation when our Domovea server indicated that the ground source heat pump had switched to cooling mode (possibly during one unexpectedly warm day) even though the pump was still heating the house via the in-floor heating.  However, after our pump was repaired, it was clear that the pump was heating the tank that is responsible for the in-floor heating but the actuators were not opening to allow heating of the floors.  This is the upstairs unit containing the actuators and valves:

 

 

 

It got pretty chilly.  Steve contacted redblue Energy and sent some screen shots of our cooling-heating set point configuration for all of our rooms except the bathrooms. He also did some trouble-shooting of his own this weekend.  It turns out that parameters had not been set for our non-bathroom rooms. Steve inputted some parameters for each room from our KNX system

 to the Domovea server.

After that, functionality of the actuators and values was restored.  We are back in heating mode.  We are still concerned about the transition to cooling mode and plan to send some more screen shots like this one to redblue Energy.

We are also struggling with the complex issue of obtaining a mortgage loan application for financing the house ("cash out financing").  We were speedily approved for a loan but the appraiser was unable to appraise the house because of the lack of comparables.  We are trying a different tactic:  our financial adviser at Morgan Stanley

has referred us to an entity that has familiarity with appraising green homes (http://starsloanservices.com/.)  We'll see how that works out.

 

In the meantime, we have been enjoying the property including our pond, the spectacular night sky

 

 

and the easy access to the pristine Western Maryland Rail Trail: 

 

 

Steve also captured this beautiful double rainbow which we think is a good omen for our new home: