Redwood Energy ZNE Tiny House Retreat Notes

I. Mutual Housing at Spring Lake Phase II a. Farmworker family apartments for low income households. Funding committed to 105% ZNE

with 5% of all energy stored off-grid. Off-grid thermal storage strategy using heat pump DHW on timers is approved by USDA funders.

b. Certified to LEED Platinum, Build It Green Platinum, DOE Zero Energy Ready Homes, EPA Energy Star and EPA Indoor Air Plus.

c. Greywater will be collected from all homes for the gardens.d. Existing Phase I used a Daiken Altherma heat pump for combined DHW and Hydronic HVAC.

That product is no longer made. VKIN makes an alternative (seen below) that comes as small as 12,000 BTU/hr (1 ton) for high rise apartment and tiny house HVAC loads.

e. Phase II Suggestions/discussion: f. Continue use of Evolve low flow/heat sensing showerheads, upgrade insulation with thermal

bridging to R-21+5 walls, R-49+5 attic, upgrade double paned windows to U=.21/SHGC .23, continue use of Nexi monitors, Energy Star appliances, LED lighting

i. Laundry drying is #1 largest energy use:1. Heat pump clothes driers, 50% more efficient but take 2x longer to dry2. Have high-speed water extraction in washing machine to reduce water needing to

be removed3. Install patio pull-out laundry lines to help some dry clothes for free on

clotheslines4. Architect need specifically draw out laundry line to ensure have privacy while

drying clothes; need to think social aspect of clotheslines

Heat Pump Dryer High Extraction Washer Retractable Laundry Lines

ii. In Phase II, use a much higher efficiency DHW, which is ~25% of the whole load. HVAC is likely less than 10% of the total load.

1. For DHW, Energy Factor increased from 2.4 up to 3.8 since 2014. A stand-alone tank like the Steibel Eltron 220e ($1400 each when bulk purchased) is the highest performance on the market according to NEEA testing, regardless of generic rating.

2. For HVAC, ducted heat pump with HSPF 9+ and SEER 14+. Highly insulated walls reduces loads to the point that highest performance HVAC is not as cost-effective as other investments.

3. Seal shower stall at ceiling = less evaporation, higher humidity, more warmth4. Drainwater Heat Recovery for second floor apartments

iii. Owner-provided High-efficiency TVs was cost-effective in Florida utility allowance calculations. Smart power strips would help, but harder to confidently model.

iv. None of tenants is interested in discussing and sharing stories. Education ideas:1. Monthly newsletter for residents, compare your energy use to neighbor or rest of

community, have conservation tips, rewards and prizes for those doing well2. Community meeting and get ideas from members, someone can facilitate, the

community members come up with plans3. FREE food at community education events. 4. Tailored letters and help to higher using tenants

II. Tiny Homesa. Lots of green building materials don’t really work as well as thinkb. Need aesthetics on pointc. Need to outsource factory that doesn’t do standard, but produces custom, high-efficiency,

healthy, green materialsd. Discussion

i. Fujitsu (highest efficiency), Mitsubishi (trusted brand), Haier (most flexibility in meeting low and high heating needs) all have products for deep snow country that can melt snow for alpine installations

1. Ductless mini-split compressor- mount on the wall, can be really high-performance

Fujitsu Halycon Extra Low Temp Heat-XLTH

Haier-Arctic Seriesii. Modular houses in Vermont built by non-profit VEIC are carefully researched ZNE

modular homes that have invested heavily in understanding the building science of best practices for snow country (https://www.veic.org/) They have a great hour long, on-line presentation, a detail of which is captured below:

https://www.youtube.com/watch?v=QSRbVTN6iSk

iii. Heat recovery ventilators save ~25% of HVAC energy, but must not be located in places that create the feeling of “cold drafts”

iv. All equipment needs to be inside, no exterior. See Bright Power’s strategy below:

v. Ground-source heat pump—really expensive. Advanced “lateral drilling” system being used in New York. Contact Michael Winkler at mlwinkle@yahoo.com for more information.

vi. Sanden CO2 heat pump, can be used in extremely cold temps down to -15F, but ONLY for DHW, or else the COP of 5 drops to 1.7 to 2.5.

vii. 3-function compressor- heat, cool, DHW- need to do Sanden (2 compressors in wall) or one compressor w small control box (less space) with tank, built-into-wall.

viii. Swamp cooler just for AC? How much space would it need?ix. Kauffman (?)- German hydronic, if did space heating and at end of loop came through

window frames… expensive?x. Solar shingles? Low efficiency. Maintenance issues. Can’t do on low-sloped roof.

xi. Spray foam? Risky for health? Instability of chemical process?xii. Batt, rigid insulation

xiii. Use high-velocity duct system, unicoxiv. One compressor w controls, 3 refrigerant lines- multi-head heat pumps. Note that they

struggle to perform as true zones.

III. Mid-Rise- Dan Johnson with Beyond Energya. Electricity expensive, gas cheap?

i. To address this- slide 3ii. No fan motors, no excess paying for, fan energy

iii. Wayyyyy less GHG emissions b. Heat recovery ventilation

i. 30-50% space heating load outside air knocked out by HRVii. Can do individual ones throughout, spaced appropriately

iii. Can do central heat recovery- put ventilator on roof, use ducts for distribution1. Exhaust return up to roof

c. Window specs- help with coolingd. Ductless mini-split = deliverye. Issue: no space for storagef. Air-to-water HP, Aermec to electrify

i. Risk to failure- aermec specificallyii. Colemec= single-pass, if bring warm water back, compressors working extra hard to raise

temperature= over-pressurizing, shutting down, bad bad bad situation! So risks are high. iii. Maybe use Sanden, can put in multiple, Colemec is second in line, then aermec= not

recommendediv. Sean O. at Ecotope- should call about circulation loads and HPs

g. Can we use drain water heat recovery from showers? Happening in Canada. h. Bank of compressors- can have another load (DHW)= ref, ref, heat recovery…

i. VRF- can integrate w HRVi. Lighting and receptacles – need to come up with a solution for these because loads don’t change

necessarily between a stnd. Gas building and an electric DHW and an E.R. Heat buildingj. Combine system in each apartment- don’t have central system

i. Went down to 9000 btu of 1 compressor, 3 jobs, 20 gallons hooked up