1. Professional design, installation and service of renewable energy systems.
Building Energy 2015
PV and Heat Pumps: Net Zero Heating
Solutions
Fortunat Mueller PE
Co Owner
ReVision Energy
March, 2015
2. AGENDA
• Introduction
• Why Heat Pumps for Net Zero
• PV/ Heat Pump Basics
• Mini Split detail
• Data
• Design Process
• Working Example
3. Who is ReVision Energy?
Engineers: Brown, Dartmouth, MIT, UNH
In House Resources: Master Plumbers and Electricians
NABCEP: 8 Certifications
Projects: More than 4,000 solar energy systems
Locally Based: Exeter, Portland, & Liberty
Each of our 75 plus employees have a vested interest in the
workmanship and long term health of the company
4. Locations :
•Liberty, ME
•Portland, ME
•Exeter, NH
Serving all of Maine and
New Hampshire
Expertise:
•Solar Electric
•Solar Thermal
•High Efficiency Heating
5. What is a Net Zero Building?
A zero-energy building, also known as a zero
net energy (ZNE) building, net-zero energy
building (NZEB, or net zero building, is a
building with zero net energy consumption.
The total amount of energy used by the building
on an annual basis is equal to the amount of
renewable energy created on site
6. Motivation
• Environmental
– Reduce CO2 emissions
– Transition away from finite fossil fuels to sustainable, renewable
energy sources
• Energy Security/Geo-political
• Economics
– Save money
– Reduce future costs and uncertainty
• Comfort
7. How do you get there?
–High efficiency NG plus very large PV to
offset all source energy
–Biomass + PV (wood or wood pellets)
–Large solar Thermal combi system + PV
–Resistive Electric + PV
–Heat Pump + PV
12. Why Heat pumps
• Low(er) Cost?
– Gas by wire for those without access
• Path to net zero with PV
• No Combustion
• Air conditioning as a benefit
• Good fit for supplemental heat
13. Why Heat Pumps
• Part of a strategy to get off oil and lower
heating costs
– http://www.rmi.org/cms/Download.aspx?id=10410&file=2013-05_HeatPumps.pdf
14. An average ME/NH home burns 800 gallons of oil per year,
resulting in more than 13,300 lbs. of CO2 emissions annually.
15. Heat Pumps and Net Zero
• Allow you to heat/cool efficiently with electricity which is easily
produced renewably on site
• By taking advantage of net metering, you can easily ‘store’ the
electricity generated in the summer to use for heat in the winter.
16. Energy Security in Reach
• Consider a very well built new home with an annual heat
demand of 40 Million BTU’s per year
– 2,000 sf ; R40/R60 insulation; Triple Pane windows; HRV
• To provide 40 MMBTU with a Heat Pump at an average COP of 2.8
requires approximately 4,185 kw-hr of electricity.
• To generate that amount of electricity in Maine requires about a
3.3 kW GTPV system.
– ~200 sf of modules
– ~$7,000 Net cost (after incentives)
For that cost you are buying all the ‘fuel’ you’ll ever need to keep your
house warm for life! That is pretty awesome.
17. In one hour enough
solar energy strikes
the earth’s surface
to supply all energy
demand for a year
Net Zero home in
Lancaster, NH
18.
19. Boothbay Botanical Gardens; Bosarge Education Center
•Built 2010
•8,000 sq ft
•20/40/60 insulation ; 1.02 ACH50 air sealing
•R7 windows
•48 kW of PV (24kW on roof/ 24kW on ground)
•VRF heat pumps
21. Grid-tied Photovoltaics (PV)
Components
Photovoltaic modules
convert sunlight into Direct
Current (DC) electricity,
which flows through cable
to the inverter.
Inverters accept the DC electricity
produced by PV modules and convert
it into Alternating Current (AC), which
then feeds demand in the building or
if there excess, feeds the utility grid.
30. Heat Pump Basics
• A heat pump is a machine or device that moves heat from one location (the 'source') at a lower
temperature to another location (the 'sink' or 'heat sink') at a higher temperature using
mechanical work or a high-temperature heat source
32. Cold Climate Air Source Heat Pumps
• Multi Stage
• Made by:
– Hallowell (Acadia)
– Nyle
– Carrier
• Inverter Compressor (ductless mini split)
• Made by:
– Mitsubishi
– Daikin
– LG
– Fujitsu
33.
34. Ductless Mini Splits
• Driving high efficiency and low temperature
performance with:
– Inverter Driven Variable speed comprssr
– Scroll Compressors
– High efficiency ECM motors
– R410 A refrigerant
• Single or Multi Split options
• Various terminal unit options
More than 50% of the air conditioning and heat pump market worldwide is
mini splits. In North America is it 2%…but growing
37. Applications
• Supplemental Heat
– Whole house supplemental heating
– Bonus Room heating and cooling
• Central Heat
– Generally in New Construction
– Open Concept design (few rooms)
– What about backup?
38. Supplemental Heat
-Usually 1 or 2 units located centrally
->(1st
unit provides bulk of the savings)
-Keep existing heating system
-Sized for partial load
-Savings depend strongly on occupant behavior
-Indoor/outdoor units usually installed back to back
39. Central Heat
-Typically in homes with better than average envelope
-Usually 1 to 2 units located centrally (sometimes more)
-Usually no full backup heating system; System sized for full load at
low temperature
-Supplemental heat in remote spaces as needed
40. Heat Pump Performance: COP
• The coefficient of performance or COP of a heat pump is the ratio of the heat supplied divided by
the supplied electrical energy.
• By definition, a resistive electric heater has a COP = 1
• Higher COP results in lower electric usage for the same amount of heat generated
• COP depends on temperature of both source and sink
41. Mini Split Performance
• Low temperature Operation
– Heat pump keeps operating down to – 13 deg F including 100%
of rated power down to 5 deg F
• COP: = 4.1 @ 47 deg F
= 2.8 @ 17 deg F
=1.7 at -13 deg F
…and you get a super efficient air conditioner too
45. Heat Pump Performance:
HSPF: Heating Seasonal Performance Factor. (BTU/whr)
Effectively an attempt to annualize COP.
(HSPF * 0.293 = annual average COP)
Must be =/> 8 for Energy Star (tax credit)
Must be =/> 10.0 for EM HESP incentive
EER: Energy Efficiency Ratio (BTU/whr)
Cooling performance at one operating point (95 deg, 80 deg 50% RH)
SEER: Seasonal Energy Efficiency Ratio (BTU/whr)
An attempt to annualize EER.
All new AC > 13
Energy Star > 14
Typical mini split: 20-26
49. Design and Install Considerations
• Sizing
• Wiring
• Refrigerant piping
• Condensate
• Noise
• Snow
• Need for Backup heat ?
• Need for Supplemental Heat?
50.
51.
52. System Design
After Sizing to the overall Design Day (Manual J) heat load:
How many indoor units (heads) do I need?
• One for each major space
• At least one per floor if you want A/C (downstairs
unit won’t effectively cool upstairs)
• Additional heads vs supplemental heat
Single split vs Multi?
• Line set length vs # of condensers
• Redundancy
• Aesthetics
53. Need for Backup Heat
Depends on system location and expected outdoor temperature range. Other
than extreme cold weather areas, many New England locations no longer need
backup heat with the newest generation of heat pumps
54. Need for Supplemental Heat
• Depends on layout of
building
• Heat loss = Heat Gain
• Rooms that have heat loss
(exterior surfaces) but no
heat source depend on dT
across interior walls for heat
gain
• dT can be uncomfortable
55.
56. Need for Supplemental Heat
Heat loss = Heat Gain
dT room to room
= (15/228) x (Room Temp-outdoor temp)
So for this small, very well insulted room, dT is generally below 5 degrees
which MAY be acceptable to some occupants depending on usage.
57. • Heat losses: ( 24 BTU/hr/degF)
• Ext Walls: 200 sq ft @ R30
• Ext Windows 24 sq ft @ R4
• Ceiling: 160 sq ft @ R40
• Inflitration: 6 cfm
58. Need for Supplemental Heat
Heat loss = Heat Gain
dT room to room
= (24/228) x (Room Temp-outdoor temp)
So for this small, still pretty well insulted room, dT is up to 8 degrees ,
which is pushing your luck for most customers
59. Always better to have it and not need it,
than to need it and not have it.
Electric resistive supplemental heat is fairly inexpensive and easy to
install (and very inexpensive to rough in for even if it is unlikely to be
needed. As a result, we recommend at least planning for it in virtually
every case.
62. Converting ‘Design Day’ load to annual heat load
If not in your modeling software, you can estimate it roughly by back calculating
based on the definition of each, along with definition of Heating Degree Day.
Design Day = Peak BTU/hr required to heat at lowest expect outdoor temp
Annual Heat Load = Total BTU required through the heating season
HDD = the number of degrees a days outdoor temp is below some base (65deg)
63. Heat Pump Lessons learned
ASHP are viable as primary heat in NNE with the right
attention to detail:
Design details:
•Outdoor unit location
• Not on the ground
• Not under drip edge
• Not on bedroom wall/ on concrete if possible
•Indoor unit location
• Where blowing air won’t be annoying
• Return HRV/ERV return air close to indoor units where possible
•Other
• Duct work adds substantial cost and is tough for more than
• Drain pan heater not really necessary in southern Maine south but may
be needed in very Northern ME, NH, VT
• Will need unit on 2nd
floor for AC if required
64. Heat Pump Lessons learned
Install details
•Trust gravity over pumps for condensate drains
•Follow best practice for leak check/comisioning which includes
high pressure test and triple evacuation.
•Check/Follow local codes to avoid costly rework
•Difficult to comission in very low ambient temperature
Operating details (owners training)
•Avoid using schedules/setback (set it and leave it alone)
•Ignore the temp shown on the remote and control for comfort
instead
•Inspect/Clean Filters regularly
•Keep outdoor unit clear
65. Example If Time Permits (Berry)
• Floor Plan
• Heat Loss
• Consider design (single vs multi) and unit
locations
• Consider backup
• Consider supplement)
• Calculate Annual Demd
• Add to plug/DHW loads
• Size PV
70. + H2O (PUZ-PW30)
- Space cooling or heating
& hot water operation
- Excellent low ambient
heating operation
Broaden the Scope Q1
2015
Image only
71. MVX Multi Position AHU
- Designed and manufactured by Mitsubishi
Electric
- Connectable with MXZ-C / MXZ H2i
- Multi position (up, down, right, left) available
- Can be used with existing ducts
- Ease of maintenance
Broaden the Scope Q1
2015
Image only
Product Highlight (tentative)
72. MVX Multi Position AHU
Specifications (tentative)
- Product Line-up: A12, 18, 24, 30 and 36
- Connectable with standard and H2i MXZ outdoor units
- External static pressure up to 0.8 In-WG
- 3 different fan speed (low-mid-high)
- Filter pre-installed
- Optional 2 stage heater
- Ability to connect with humidifier and ERV
73. Thanks for attending NESEA Building Energy 2015.
Questions or comments:
Fortunat Mueller
fortunat@revisionenergy.com
207-221-6342
www.revisionenergy.com
Notas do Editor
Started in Liberty back in 200x then expanded to portland in 2006. Now working on Portsmouth
First, why would you consider NZEB in the first place? There are lots of good reasons.
Passive house in Belfast. By GO Logic.
Photo of Hea tPump Plus PV
Particularly acute problem for New England for whom oil heat represents a $14Billion dollar annual economic drain
Problem with CO2 pollution is that it is invisible, so carbon visual helped us with this slide.
That is all exciting and everybody loves saving money but the reason I certainly wouldn’t be here talking about heat pumps if it were just a cheap way to heat a house. What makes us excited about mini splits is that it creates a viable path to carbon neutral or net zero homes, even for those folks not excited about burning wood.
You can make electricity off the roof. You can’t make propane off the roof.
Credit Keith, Kaplan Thompson, Alan Gibson. This is a carrier heat pump.
Also possible as a partial solution in retrofit
Photo of Hea tPump Plus PV
Commercial example; not typicall enough roof, so this is mostly ground mounted. BB Botanical Gardens is another one
Commercial example; BB Botanical Gardens is another one; Scott Simons Architect, Bensonwood.
PV Cell, Module (combination of cells), Panels (one or more fastened together), Array (one or more wired together for specific voltage), Charge Controller (regulates battery voltage), Battery (device that stores DC electrical energy), Inverter (changes DC to AC current, <5% loss), DC & AC loads
PV Cell (60 per panel at .5 volts each), wired in series to produce 30V, 7.8 Amps, approx 235 watts peak power – Array of 20 gives you a 4700 watt system or a 4.7 kw
Crystalline (mono or poly) silicon (one of earths most abundant resources)cell is a semi conductor (properties of an insulator and conductor) . Add impurities such as boron and phosphorous to create a permanent imbalance creating movement of electrons. Sunlights strikes a cell it knocks loosely held electrons from the negative layer.
Thin Film – Amporphous silicon. Inexpensive to manfacture, ½ efficiency, limited warranty, aesthetically pleasing
Photo of Hea tPump Plus PV
TIME CHECK: Should be about 1:15 in
This is the part of the presentation where I’ve typically talked about, the difference between temperature and heat, definitions of sensible and latent heat and the Clausies statement of the 2nd law of thermodynamics but..
Actual photos from my presentation at BE2014 presentation last year
Refrigerator is really a type of Heat pump. If you took the door off your refrigerator and pushed it into the entry way of your house, it would be a really crappy heat pump. Notably most heat pumps are ‘reversible’ so the Evaporator becomes the Condensor and vice versa, turning a heating appliance into a cooling appliance and vice versa
These are the two main types you’ll see.
We hear a lot about the Nyle and Acadia because they come from Maine. They also got a lot of press (most recently some bad press).
I’m going to focus primarily on the inverter ductless mini split because they are the ones driving the state of the art
In one test at Mitsubishi, installing variable speed compressor s (and nothing else) in an existing system reduced energy consumption by up to 70%
The other nice thing about ductless is that they are so much easier to install in renovations or well insulated spaces where duct leakeage is always an issue
Indoor unit options
Half Way BREAK?
COP is really like efficiency. Unlike efficiency it can be >1. In fact it really should be otherwise what’s the point.
Note that if you are talking about an honest COP it needs to include ALL the power used for the system (often pumps are ignored or defrost cycles are ignored)
Air source heat pumps also use some of the refrigeration terms like HSPF and SEER and EER.
Acadia was making news when they said they were in pure hp operation to 10 or 15 deg F (and then call on strip heat). Now we’re 20 degrees cooler…
Cooling mode SEER 20.2 compared to a good window unit is about 10. (meaning half the elecrtrical cost for the same cooling)
But which COP matters?
Electric at 14 cents, Propane at 2.70 (which is probably too cheap)
This is actually the CM, not the H2i.
The flat propane curve is only correct to a first order
Most of the heating hours occur between 20 and 50 degrees ambient temperature
That is a bit deceptive because obviously the hours at low temp require more heat, but still.
So how is the performance of these systems at these typical operating temperatures
What about operating costs?
RLS3 SEER up to 33
Historically has not been a lot of data and a lot of data that we do have is anecdote (or electric bill based)
Bruce and Mark each have presented data from a home or two. They show the variation we expect, but those who monitor heat pump directly tend to find average annual COP in ME/NH/VT to be about 2.8-2.9. Southern NE can expect something a bit higher.
About 2 hr
Design Process for new consruction
Just a bit more critical to make sure you have the whole team together (builder, architect, homeowner, HVAC, solar, ventilation) early
Bangor Maine record temp
Note the 15,000 BTUHR RLS2 is still making 16,500 BTU/hr at -5 deg F
Bangor Maine record temp
Note the 15,000 BTUHR RLS2 is still making 16,500 BTU/hr at -5 deg F
We used to just waive our hands and say it should be fine, but we finally bucked up to do some math.
15 BTU /hr per deg F to outside
228 BTU/hr per deg F to inside
Plus any internal gains (not counted)
Con
For example in Maine we design around a 70 degree indoor temp and -5 deg outdoor temp (dT= 75) as design day.
So a full day at -5 degrees gives you: 70 heating degree days.
So take the DD load, multiply by 24 and divide by 70 to get BTU/HDD
Then multiply by HDD and fudge factor to get anuall
