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

AGENDA• Introduction

• Why Heat Pumps for Net Zero

• PV/ Heat Pump Basics• Mini Split detail• Data

• Design Process

• Working Example

Who is ReVision Energy?

Engineers: Brown, Dartmouth, MIT, UNHIn House Resources: Master Plumbers and ElectriciansNABCEP: 8 CertificationsProjects: More than 4,000 solar energy systemsLocally Based: Exeter, Portland, & Liberty

Each of our 75 plus employees have a vested interest in the workmanship and long term health of the company

Locations :•Liberty, ME•Portland, ME

•Exeter, NH

Serving all of Maine and New Hampshire

Expertise:

•Solar Electric•Solar Thermal

•High Efficiency Heating

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

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

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

Pellets + SHW + PV

SHW + PV + Resistive Electric

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

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

An average ME/NH home burns 800 gallons of oil per year, resulting in more than 13,300 lbs. of CO2 emissions annually.

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.

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.

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

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

Grid Tied Solar Basics

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.

How a GTPV System Works

Residential PV Systems

Residential PV Systems

Net Metering & Inverter Technology Replaces Batteries

Basic Solar Facts

• 1,000-1,300 kwhr/kw/year in New England• 50-70 sf of modules per kW• Installed cost $2.90-$4/watt (2014)

Thermodynamics 101

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

Types of Heat Pumps

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

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

Single vs multi split

• Single Split • Multi Split

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?

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

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

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

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

Mini Split Operating cost comparison

Temperature BIN data

http://www.efficiencymaine.com/at-home/home-energy-savings-program/heating-cost-comparison/

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

Ecotype reports

http://www.nrel.gov/docs/fy11osti/52175.pdfhttp://neea.org/docs/reports/ductless-heat-pump-impact-process-evaluation-field-metering-report.pdf?sfvrsn=16

Bruce Hartley, VT

M Rosembaum, MA

Design and Install Considerations

• Sizing• Wiring

• Refrigerant piping

• Condensate• Noise• Snow • Need for Backup heat ?

• Need for Supplemental Heat?

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

Need for Backup HeatDepends 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

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

Need for Supplemental HeatHeat loss = Heat GaindT 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.

• 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

Need for Supplemental HeatHeat loss = Heat GaindT 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

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.

Supplemental Resistive Heat options

http://econo-heat.com/us/online-shop/http://www.eheat.com/ http://www.convectair.ca/us/index.htmlhttp://www.runtalnorthamerica.com/

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 tempAnnual Heat Load = Total BTU required through the heating seasonHDD = the number of degrees a days outdoor temp is below some base (65deg)

Heat Pump Lessons learnedASHP 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

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

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

The Future

Whole Home Solutions

PUZ-PW30+ H2O

PUZ-HA42H2i

PVAD Multi PositionAHU

+ H2O (PUZ-PW30)

- Space cooling or heating & hot water operation

- Excellent low ambient heating operation

Broaden the Scope Q12015

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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 Q12015

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Product Highlight (tentative)

MVX Multi Position AHUSpecifications (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

Thanks for attending NESEA Building Energy 2015.

Questions or comments:Fortunat Muellerfortunat@revisionenergy.com207-221-6342www.revisionenergy.com