Monday, October 8, 2018

Passive House Tour Veterans Day Weekend!


Rochester Passive House will be open for tours on:

Friday November 9th, 2018 from 12pm - 5pm

Saturday November 10th, 2018 from 9am - 4pm


If you are planning on building or renovating this is a CAN'T MISS EVENT! 

  • High Performance Windows
  • Whole House Ventilation
  • Super Insulation
  • Air Tight Thermal Bridge Free Construction
  • Indoor Air Quality Monitoring
  • Superb Comfort
  • AND EXTREMELY LOW ENERGY USAGE

We will be collecting donations for the 

Veterans Outreach Center

Check out this link for items needed.

If there are any questions feel free to reach out to:
Matthew Bowers
RochesterPassiveHouse@gmail.com






Tuesday, July 24, 2018

The Summer of HEAT and HUMIDITY - Passive House Comfort Performance

The Summer of HEAT and HUMIDITY
Passive House Comfort Performance



CAUTION: THERE IS SOME VERY TECHNICAL DATA HERE.

If you understand things like Psychrometric Charts, Enthalpy, ASHRAE 55 (comfort criteria), and Indoor Air Quality Metrics, you may like this post.


It has been a while since I did a blog post that didn't have to do with an open house, so I am going to be a little rusty - and buckle in, it is a long one!


As everyone knows, this has been a very warm summer, and we have been dealing with some very humid conditions as well. I thought that this would be a good opportunity to see how Rochester Passive House performs to the standards for comfort. You can also be the judge if you'd be comfortable.


The purpose of this post is to show how effective the "minisplit per floor" method of cooling is in a Certified Passive House AND to show how we maintained superb Indoor Air Quality despite Poor Air Quality warnings from the local weather stations. Here is the set up:

1) 9000 BTU Ductless minisplit is located in the Master Bedroom on the south end of the house
2) uHoo IAQ Meter in kids bedroom on North Side of the house.
3) Netatmo Weather Station located on the front porch out of the direct sunlight


I put the uHoo IAQ meter in the kids bedroom for a few reasons
1) I have 2 girls - age 8 and 6 who share a room (2 occupants = higher potential CO2)
2) This room on the north east side of the house on the 2nd floor seemed to me be to be the most difficult to cool
3) I care about the IAQ for my kids, so I wanted to see if there was a problem in their room
4) They have a pretty routine bedtime and wake up time every day, so I figured my numbers would be consistent between the days. (8pm bedtime, 7am wake up - YES EVEN IN THE SUMMER)

Now, our method for cooling with the minisplits were:
1) We kept the master bedroom door open every day and all night
2) We closed the kids door every night - they did open it a few times to go to the bathroom etc, and left it open. 
3) We did do laundry at our normal rate, about 5 loads per week with a condensing dryer
4) Our Zehnder system was on "normal" except for times of boosting (showers and cooking)
5) The minisplit in the Master Bedroom was kept on "dehumidify" I figure it is trying to maintain 60% RH regardless of temperature. I can't find a good explanation on this anywhere.
6) Our 1st Floor minisplit was either set at 72F or Dehumidify - we change it around for comfort

Just How Hot Was it?

The typical HVAC design criteria for Rochester, New York is set for 1% and 99%. This means the outdoor temperature will only exceed the design temperature 1% of the hours of the year.  

Rochester NY Cooling Design Temperatures - from ACCA Manual J are:
1% Cooling - 86 F 50% RH

Because I will be discussing Temperature AND Humidity we will convert things to Enthalpy for comparisons. Simply put, the higher the Enthalpy, the higher the total heat content in the air. 

86 F with 50% RH has and Enthalpy of 35.3 BTU/lb

What does this look like on a Psycrometric Chart?



Okay, lets take a look at the outdoor weather from 9am June 28th - 7am July 6th
This is a mapping of temperature and humidity readings every hour for that 8 day period 
There are 191 measurements.

Of the 191 hours in this time period the Enthalpy for design was exceeded for 115 hours!
(There are 115 red dots above the red line)

I am not making an argument for or against the design limits set by ACCA, I am simply showing how hot it was over this week. 

60% of the time we were exceeding the design temperature limits for our cooling system.

--------------------------------------------------------------------------------------------------------------------------

Lets Define Comfort

ASHRAE-55
"The purpose of this standard is to specify the combinations of indoor thermal environmental factors and personal factors that will produce thermal environmental conditions acceptable to a majority of the occupants within the space"

That is a lot to digest, so lets unpack that a little bit:
1) Thermal Environmental Factors - things like temperature, mean radiant temperature and humidity etc.
2) Personal Factors - things like the amount of clothing you are wearing, your activity levels etc.
3) A majority of the occupants - lets face it, we can't make EVERYONE happy, some people like it warm, others like it cool.

There are a few different models you can use to meet this standard -
1) Graphic Comfort Zone Model - to use this model you must meet the following criteria:
  • metabolic rate must be between 1.0-1.3 - For intermittent activity, you take the average
    • 0.7 - sleeping
    • 1.0 - seated and quiet
    • 1.2-1.4 - light activity
    • 2.0 - walking, lifting heavy loads
    • Anything higher has a low level of design accuracy
  • Humidity ratio must be below 0.012 lb H2O/lb dry air
    • that is 84 grains H2O per lb dry air
2) Analytical Comfort Zone Model - If either or both of your above criteria are too high, you use this method.
  • Utilized this comfort tool model with inputs of:
    • Operative Temperature (or Air Temperature and Mean Radiant Temperature)
    • Air Speed
    • Humidity
    • Metabolic Rate
    • Clothing Insulation
  • These inputs are evaluated to predict a thermal sensation on a -3 (cold) to +3 (hot) scale
    • You comply if the conditions show thermal "neutrality" between -0.5 and +0.5
Okay! WAKE UP! Moving On....
EN-15215 
This is the European Standard for comfort. 
For what I am trying to show within a Certified Passive House, EN-15251 and ASHRAE-55 are pretty similar. Since there is no temperature asymmetry and I am utilizing the residential standard for comfort (ie: we are not designing to maintain an exact temperature and humidity, like we would in a museum or hospital) the 2 standards are close enough without writing a book. 

I am simply trying to show how well we achieved summer comfort when the outdoor conditions exceeded our design conditions for an extended period of time.

--------------------------------------------------------------------------------------------------------------------------
Comfort Criteria Assumptions:
  • I will utilize the Analytical Comfort Zone Model via http://comfort.cbe.berkeley.edu/
  • When the Kids are "sleeping" the MET will be 0.7 - 8pm-7am
  • When the Kids are awake and during the day the MET will be 1.0
    • The room is typically unoccupied during the day, but I have the data so lets look at it
  • The Clothing Level (Clo) at night will be 2.0
    • Kids in summer PJ's under a blanket on top of a mattress
  • The Clothing Level (Clo) during the day will be 1.0
  • The house is airtight, there is no ceiling fan and the way the ventilation system is designed there is no noticeable air velocity in the room. The Standard seems to have a 30 Feet Per Minute default, so we'll go with that (30 feet per minute = 0.34 miles per hour)
  • The Mean Radiant Temperature is 77 F. This is a guess and tends to be the standard default. but there are no computers, electronics or other internal gains in the room other than the 2 girls. One alarm clock is the only thing plugged in. There is also 1 Passive House Window that faces east, so by 11 am it is completely shaded. The walls, floor and ceiling temperatures were measured with an IR Camera showing about 75.2 F
Kids Room Nighttime Comfort

So what does this mean?
  • There were 96 hours where the kids were in their room "sleeping" over this time period
  • The Average Predicted Mean Vote or PMV needs to be between 0.5 and -0.5. In this model the Average PMV is -0.06 - Thermal Comfort is achieved.
  • The conditions in the bedroom stayed within the comfort zone (indicated by the light purple shading) the entire time.
Kids Room Daytime Comfort

  • There were 95 hours during the day 
  • The Average Predicted Mean Vote or PMV needs to be between 0.5 and -0.5. In this model the Average PMV is +0.07 - Thermal Comfort is achieved.
  • The conditions in the bedroom stayed within the comfort zone (indicated by the light purple shading) the entire time.

You will notice a slight shift in the light purple comfort zone, due to different met rates and clothing levels. 
--------------------------------------------------------------------------------------------------------------------------

So that is great, Thermal Comfort is achieved even when the temperatures are extreme for a long period of time. All without conditioned air distribution. But what about the indoor air quality?


The uHoo meter is measuring and data logging lots of air quality conditions every minute of every day. It also has tapped into the EPA's recommendations on limits for exposure on each. I get a notification when any one of these items exceeds the EPA's limits.
  • Temperature -        Notification at 77 F
  • Humidity -              Notification at 60 % (or below 35%)
  • CO2 -                       Notification from 1000-5000 ppm - Warning over 5000 ppm
  • Total VOC -            Notification from 400-800 ppb - Warning over 800 ppb
  • PM2.5 -                   Notification from 50-100 ug/m3 - Warning over 100 ug/m3
  • NO2 -                       Notification from 100-250 ppb - Warning over 250 ppb
  • CO -                        Notification from 35-70 ppm - Warning over 70 ppb
  • O3 -                          Notification from 55-70 ppb - Warning over 70 ppb
  • Air Pressure -         Below 970 mbar or above 1030 mbar indicating a sever weather event
To save time and effort, I will omit the following readings since they didn't change the entire week:

Temperature and Humidity - I don't need to beat a dead horse
Carbon Monoxide = 0 ppm all the time
Air Pressure = 986.5-1003.6 mbar all the time

New York State Measures a variety of Outdoor Air Quality Metrics available to anyone at any time. Here is the Website link:
http://www.nyaqinow.net/
The Nearest Station to me is roughly 13 miles away.

Lets take a look at PM 2.5 measurements

PM2.5 is "Particulate Matter" that are 2.5 microns or less in width. That is a fancy way of saying "tiny dust". PM 2.5 is small enough that the body cannot filter them out when inhaled and thus enter our lungs and get absorbed into our blood.
According to the EPA you want to maintain between 0 - 50 ug/m3

My kids room vs. Ambient for the same time period:


The Blue Line is Outdoor Measurements from the NYS website.
The Orange Line is Indoor Measurements from the uHoo Device.

Over this time period:
the Outdoor Average PM 2.5 was: 10.8
 the Indoor Average PM 2.5 was: 6.1 (and never exceeded 8.1)

Lets take a look at NO2 Measurements

NO2 forms from ground level emissions related to burning fossil fuels from vehicles, power plants,
and off road equipment. According to the EPA scientific evidence links short-term NO2 exposure, ranging from 30 minutes to 24 hours, with adverse respiratory effects including airways inflammation in healthy people and increased respiratory symptoms in people with asthma. You want to stay under 100 ppb
The Blue Line is Outdoor Measurements from the NYS website.
The Orange Line is Indoor Measurements from the uHoo Device.

Over this time period:
the Outdoor Average NO2 was: 4.3
 the Indoor Average NO2 was: 0.5 (and never exceeded 0.6)

Lets take a look at Ozone (O3) Measurements

Ozone is not directly emitted into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and Volatile Organic Compounds (VOC's) in the presence of sunlight. Breathing ozone can trigger a variety of health problems, particularly for children, the elderly and people with lung disease and asthma. You want to maintain levels as low as possible because breathing low levels over a long period of time may have more damaging and longer-lasting effects.
The safe level according to the EPA is under 55 ppb, however inhaling fairly low levels can still result in signs and symptoms such as coughing, congestion, etc.

The Blue Line is Outdoor Measurements from the NYS website.
The Orange Line is Indoor Measurements from the uHoo Device.

Over this time period:
the Outdoor Average O3 was: 38.6 ppb
 the Indoor Average O3 was: 4.0 (and never exceeded 4.4)

DISCLAIMER: Ambient Total VOC and CO2 are not currently measured by NYS.
I don't have data to the compare the indoor conditions to. I have moved the uHoo devide outside, and I taking some measurements to see how CO2 and TVOC (and all of the other measurements for that matter) varies. That data will be posted when I see something interesting.

Lets take a look at Total VOC Measurements

VOC's are carbon based chemicals that are emitted as gases from solids or liquids. While most people can smell high levels of some VOC's, others have no odor. There are thousands of different VOC's produced in our every day lives (Paint, Cleaning Solutions, Wood Products, Cooking, Air Fresheners,etc. etc.). The EPA recommends adding ventilation when above 400 ppb, and avoiding concentrations over 800 ppb.


The Orange Line is Indoor Measurements from the uHoo Device.

Over this time period:
 the Indoor Average TVOC was: 64.5
The 400 ppb limit was exceeded for 2 hours with a max reading of 471.9.

There is no direct correlation between an outdoor measured condition and the indoor condition for TVOC. I have been reading TVOC measurement outdoors as of late and have seen readings as high has 317 ppb, so it is plausible the indoor VOC spike was caused from an outdoor concentration spike.

Lets take a look at CO2 Measurements
CO2 concentrations are generally related to the number of occupants. It is usually highest where people and pets spend most of thier time. Some other sources include, combustion appliances, and from experience - bread baking (and rising). CO2 is generally considered to be 400 ppm in outdoor air. The ideal state is under 1000 ppm in the house. Elevated levels can lead to drowsiness, but no serious health effects until you exceed 5000 ppm. Headaches, increased pulse rate, decrease in cognitive thinking etc. can result.

Our ventilation system is designed to maintain roughly 600-700 ppm CO2 in the house (or 200 ppm above ambient).

The Orange Line is Indoor Measurements from the uHoo Device.

Over this time period:
 the Indoor Average CO2 was: 795

The 1000 ppm limit was exceeded on 5 occasions.  There are a few reasons for this.

  • Outdoor ambient CO2 was likly high. On recent warm muggy nights I have seen the outdoor CO2 creep up to as high 632 ppm. 
  • Ventilation Rates not high enough with high ambient CO2. While the system is designed to keep the CO2 levels in the 600-700 ppm range, it does consider that our winters are longer and CO2 concentrations are lower in the winter. 
  • Extremely warm and humid nighttime temperatures are difficult for any cooling / ventilation system. 

We have an interesting dilemma here. On the worst night for CO2 concentration, our low temperature was 75.8 F with a 86% RH. If we increase our ventilation rate to lower the CO2 concentration we jeopardize the indoor comfort levels due to excess humidity. We do have an ERV, but when it is used in conjunction with the Comfofond typically it runs in bypass. This is because the Comfofond is lowering the temperature of the incoming air below the temperature of the extract air (ie: "Free" Cooling). When it cools the incoming air with the ground loop, the fresh air is near the saturation temperature (meaning it is very humid, but cooler). Usually in the 65-70 F range. 

For more information on my ventilation system see my previous blog post HERE

Because the CO2 levels are only elevated for a few weeks out of the year; 
AND they are no where near the dangerous levels 
AND all of the other indoor air quality metrics are within limits 

We are certainly satisfying any concerns of comfort with a spot source cooling unit.  

Wednesday, May 16, 2018

Passive House Tour June 9th

CERTIFIED 
PASSIVE HOUSE 
TOUR


340 Quaker Meeting House Rd.Honeoye Falls, NY 14472

June 9th 

10a - 6p

How comfort is achieved though energy efficiency!

Passive House is a building standard that is truly energy efficient, comfortableaffordable and ecological at the same time. It is not a brand name, but a construction concept that can be applied by anyone and that has stood the test of practice.

Who should Come?
  • Anyone interested in Energy Efficiency
  • Anyone looking to build a new house
  • Architects, Engineers, Professors, Students
  • Local Government Officials, Policy Writers
  • Builders, and Remodelers
  • EVERYONE
If you want more information reach out to Matt Bowers at
RochesterPassiveHouse@gmail.com

Hope to see you there!

Thursday, January 11, 2018

2017 Utility Data

2017 Energy Data


To meet International Passive House (PHI) Standards the house must be built to the following performance criteria:

  • 4.75 kBTU/sf/yr - Heating Demand (or 3.17 BTU/hr/sf Heat Load)
  • 5.39 kBTU/sf/yr - Cooling Demand
  • 38.0 kBTU/sf/yr - Primary Energy (2.6 Source Energy Factor)
  • Thermal Bridge Free
  • Airtightness below 0.6 ACH50

To meet Passive House US (PHIUS) Standards the house must be built to the following performance criteria - this is based on Climate Zone 5 (Rochester International Airport)

  • 6.0 kBTU/sf/yr - Heating Demand
  • 2.2 kBTU/sf/yr - Cooling Demand
  • 6200 kWh/per person/yr - Primary Energy (3.16 Source Energy Factor)
  • Thermal Bridge Free
  • Airtightness below 0.05 CFM50/sf envelope area
* Keep in mind the way both standards measure sqft is different
** Watch our for UNITS! kBTU and kWh

To keep this post relatively short, we will only focus on the 1st 3. I suppose you'll just have to trust me that we are still below the airtightness and we are thermal bridge free.

I have compiled all of the energy data from 2017. Here is a quick break down of the different components I have been metering over the past 12 months:

Over the past year, my total electric usage - according to my bill was 8129 kWh - $1050.63
Here is the Breakdown, based on my meter readings:


*** I estimated the electric use for the water heater or ventilation system for January 2017 because I didn't install my meters on those components until Feb 1, 2017

Here are some comments on the utility data breakdown:

  • My largest single expense was the $17/month Service Charge
  • My Average monthly bill is $87.55
  • The 10 year average HDD for Rochester, NY is 6265
  • 2017 had 5766 Heating Degree Days - so it was a "warm" winter.



Okay this is all great, but low utility bills are objective. After all, this barn used 100% less energy than me last year:
(This is also a case when a single pane window is more efficient than a wall)

This is where comfort comes into play. Now here is Western NY I have done plenty of Energy Audits and people will go to some pretty extreme lengths to keep their heating bills as low as possible. I have heard the following quotes more than once:

"We turn the thermostat back to 55 F at night"
"We only set the thermostat to 64 F during the day"
"We don't heat the upstairs"
"We don't heat the basement"
"We don't heat the extra bedrooms"
"We burned 9 cords of wood last winter"

I've heard them all.

Well, obviously we have done none of that, and we have kept the whole house warm (or cool) all year.

I downloaded the weather data from my NETATMO weather station (Its a really cool device that can give you more data than you'll ever care to analyze).

I took a look at every day last year and took the high and the low temperatures - both indoor and outdoor. Then I averaged the high temperatures over the course of each month and I averaged the low temperatures for each month and made this graph:
The Blue Line is the Outdoor Average Maximum temperature for each month
The Red Line is the Outdoor Average Minimum temperature for each month
The Green Line is the Indoor Average Maximum temperature for each month
The Purple Line is the Indoor Average Minimum temperature for each month.

Basically the Outdoor Temperature was between the Blue and Red Line most of if not all of the year.
On the same note, the Indoor Temperature was between the Green and Purple line most of the year.

Here is some interesting notes:
  • We maintained the indoor temperature between 70-72 degrees for most of the year (Close to 80% of the time)
  • The highest recorded indoor temperature was 79 F - this is because we had a 72 F day on Feb 24th. I was NOT going to turn on the A/C is February. 
  • The lowest recorded indoor temperature was 64 F - this was because I left too many windows open overnight to achieve some passive cooling in September.
  • There have been a few times it has been colder than 30 F outside and we have had to open windows to cool off. This does mess with the Relative Humidity a little bit. On Christmas Day 2017 we had to open windows to cool down the house with company over. We were at 75 F inside.
  • In the summer the heat pumps only ran in the "dehumidify" mode (where they try to maintain 60% RH), and we only turned them to A/C with a set temperature when we were gone for a week for vacation.
  • I will be doing a ERV vs. HRV post in the future so I don't want to go into too much detail, but we have swapped to the ERV core for the winter to help maintain RH. From January-March we struggled to keep the RH around 30-35%. So far this winter we are in the 40-45% range - even with the bomb cyclone dropping temps here to around 0 F for a few days. 
  • For 80 % of the year we are in the 40-60% RH. The other 20% is due to opening windows for passive cooling in the shoulder months - when it gets down to 55 F at night and 90% RH. Then heats up to 80 F during the day at 60% RH. I am not good enough with Excel to show you a graph of that. 
Okay, Back to the Utility Data:
Now to take a closer look at how we used our Energy compared to the PHI and PHIUS Standard: The number on top of the Bar Graph is the Passive House Limit. The number in the blue is the 2017 energy use for RPH.

One quick note on the primary energy from PHIUS. It is calculated as 6200 kWh per person per year divided by 3.16 (losses in the grid). The number of "persons" is based on number of bedrooms +1 (just like RESNET). We have 3 bedrooms and an office without a closet. For purposes of this calculation included the office as a bedroom. Amazingly, that closet matters! We currently have 5 people living in the house, so I figured it was okay. I know neither standard is perfect but seems silly that the difference between certification and not is whether or not you build a closet in a room.

Thanks for taking the time to read, and if I messed up any of my calculation I'm sure someone will tell me. 

I'll be working on a post for HRV's VS ERV's and my experience with both shortly.


Tuesday, January 2, 2018

Glazing Surface Temperature

Glazing Surface Temperature

DISCLAIMER: This is for informational purposes only, I only own an IR Camera and I am NOT a certified thermographer. I know enough to be dangerous, and that is about it!

Here is my attempt at figuring out the glazing surface temperature at Rochester Passive House. I did 2 different scenario's.
                 1) Full Solar Gain - South facing window
                 2) No Solar Gain - Breezeway (north) door glass

Here were my test parameters:
                                         Full Solar Gain:                                 No Solar Gain:
                                 

The difficulty with finding an actual glazing surface temperature is glass tends to reflect quite a bit, so you are not reading the glass temperature, but the temperature of what is reflecting on the glass.

You can see my reflection in this IR Photo. 

To get closer to an actual glass surface temperature I took a scrap piece of paper, and covered half with black electrical tape, and covered the other half with 2 layers of painters tape. I taped this square to near the center of glass and let it sit there for a while. I am going to assume the paper will become the same temperature as the glass.

This is the paper I taped to the glass. I needed to make sure the paper was completely opaque. I used black electric tape for half, and 2 layers of painters tape for the other half. According to FLIR electrical tape has an emissivity of about 0.95. The painters tape is not as shiny (lower emissivity) but I wasn't sure if how the black tape would show a hotter temperature with the solar gain. 

Here is the Solar Gain Photo:
You can see, the black tape is hotter than the painters tape. But both of them are in the 103-106F range. The hottest temperature is not centered in on the black tape because of the angle the sun is hitting the exterior glass.
I have 2 images for the shaded glass
This one was taken roughly 1.5 ft away at a slight angle. It is roughly 65F
This one was taken about 6" away, but you can see how varied it is, there is quite a bit of reflection going on - but the average temperature is about 62 F

Because I was going in and out of the breezeway multiple times, the breezeway door and interior walls may be a few degrees cooler than normal. I took an IR photo of the interior wall, next to the breezeway door and it was 65F. I didn't post it because it is just an orange square - nothing really to see. 

Summary:
IN WINTER EXTERIOR CONDITIONS
Glazing Surface Temperature of South Windows in full sun = 100-105F
Glazing Surface Temperature of Windows in full shade = 60-65F - within 7F of indoor air temperature.

 Someday I am going to do this with an Energy Star Window and compare. 

Thermal Imaging Scans or Rochester Passive House

Rochester Passive House Thermal Image Scan

To close out 2017 I thought it would be a good idea to do on IR scan of the house while it was really cold outside to mimic my Summer IR Scan. Here they are:

Rochester Passive House Summer IR Scan

Rochester Passive House Winter IR Scan
 


Wednesday, August 2, 2017

Passive House Standards Met

Passive House Standards Met
It has been just over 1 year since we moved into the house. I finally have about 1 years worth of data (minus cooling for this year). Here is where we stand:

One really nice thing about PH International is the simplicity of the standard. I don't mean it is simple to achieve, but it is simple to explain.
1) Airtightness under 0.6 ACH50
2) Heating Demand - 4.75 kBTU/sf/yr
3) Cooling Demand - 5.39 kBTU/sy/yr
4) Primary Energy - 38.0 kBTU/sf/yr
5) Thermal Comfort / Thermal Bridge Free design - Blog post to come!

So lets do some unit conversions, since my house is totally electric - so my calculations are in kWh:

  • Heating Demand - 1.39 kWh/sf/yr
  • Cooling Demand -  1.58 kWh/sf/yr - I'm told this is to account for dehumidification being energy intensive. 
  • Primary Energy - 11.1 kWh/sf/yr
Lets see how we did - Our PHPP model shows 2930 sqft

1) Airtightness: My previous blog posts shows how we met this standard comfortably

2) Heating Demand: I installed 2 electric meters measuring my 2 air source heat pumps that I read monthly, so I can accurately measure my electrical consumption for Heating and Air Conditioning.

  • The top meter measures the Water Heater electrical consumption (installed on 2/1/2017)
  • The bottom left measures the 2nd floor minisplit heat pump (installed on 10/25/2016)
  • The bottom right measures the 1st floor minisplit heat pump (installed on 10/25/2016)
I should note, we had not used the minisplits for heating until after the meters were installed.


My electrical use dedicated to heating over the 2016-2017 winter was: 1730 kWh

1730/2930 =
0.59 kWh/sf/yr or 2.02 kBTU/sf/yr

The 2016/2017 winter had 5593 Heating Degree Days - our 30 year average is about 6380. So our winter was about 12% warmer than normal, but we are less than 1/2 of the PH limit of 4.75 kBTU/sf/yr

3) Cooling Demand: We are not done with cooling for this summer yet (it is early august). But we can interpolate a little bit. So far for the summer of 2017 we have used 187 kWh

187/2930=
0.06 kWh/sf/yr or 0.22 kBTU/sf/yr

As long as I don't use 4,400kWh the rest of the summer I will be under the limit (remember I've only used 187 so far this summer)

4) Primary Energy: Now that I have a full year's worth of electric bill I can do this calculation. The primary energy portion of the Passive House accounts for grid losses (The assumption is the grid is 38% efficient). We moved into the house in July 2016, so August 2016 was our 1st full month of utility bills. This number includes all of the heating, cooling, water heating, ventilation, cooking, plug loads, etc. 
 Here is our Monthly breakout of usage:
August 2016             685 kWh -  $85.53
September 2016       573 kWh -  $75.15
October 2016           452 kWh -  $63.80
November 2016       622 kWh -  $73.63
December 2016       968 kWh - $103.94
January 2017         1232 kWh - $142.60
February 2017         957 kWh - $121.58
March 2017             848 kWh - $93.68
April 2017               633 kWh - $79.51
May 2017                418 kWh - $65.79
June 2017                474 kWh - $66.36
July 2017                 537 kWh - $75.48
Total                      8399 kWh - $1,047.05

2.6 x (8399/2930)= 
7.45 kWh/sf/yr or 19.37 kBTU/sf/yr

Again, we are FAR under the limit of 38.0 kBTU/sf/yr.

I do have a meter on the water heater and ventilation system but I installed it in late January, so I don't really have meaningful data yet. But this is what I have so far:

The Water Heater Electrical usage so far has been:
February 2017    136 kWh - $14.86
March 2017        166 kWh - $15.01
April 2017          113 kWh - $11.16
May 2017           104 kWh - $12.14
June 2017             86 kWh -   $8.96
July 2017             69 kWh -    $7.51
Total                   674 kWh - $69.64

The Ventilation System Electrical usage so far has been:
February 2017    38 kWh - $4.15
March 2017        42 kWh - $3.80
April 2017          34 kWh - $3.36
May 2017           32 kWh - $3.74
June 2017           42 kWh - $4.37
July 2017            46 kWh - $5.01
Total                  234 kWh - $24.43

Lets take a look at how my electrical bill breaks out for 2017:

(This is only from January on, so the heating number may seem misleading since it is only for half of the winter)
The 2 things that stand out to me are:
1) The $17 per month service charge certainly adds up fast!
2) I am surprised at how little the ventilation system costs to run considering it is the only piece of equipment in the house that runs 24/7 (roughly $4 per month to operate - and that includes the Comfofond ground loop!)

I hopefully will have some news on the Certification front soon! Passive House Academy is working on it!