The Prototype Classroom -A Deep EnergyRetrofit at the Plainfield, NH School

Marc Rosenbaum, P.E. Energysmiths Meriden, NH

Plainfield, NH K-8 School

About 35,000 sf, built 1972, 1989, 2000Five year average oil usage > 21,000 gallons/yrSteadily rising electrical usage >215,000 kWh/yr

An active Facilities Committee has reduced thesenumbers over 6,000 gallons/yr and over 34,000kWh/yr, with some airsealing and insulation plusoperational changes.

1989 Addition

2000 Addition 1972 building

Floor Plan

1989 Addition

2000 Addition

Gym

1972 building

Prototype Classroom

• The H/V system is oil-fired forced hot water with rooftop H/V units and unitventilators, all past their useful service life.

• Temperature swings and variations of 20F are common.

• Air quality and comfort are poor.

• A DDC system that cost ~$21,000 has been a failure.

• The building walls are T-111 plywood and are decaying and delaminating.

• Much of the window hardware has failed and the windows have decayed.

• A complete rebuild and upgrade of the H/V systems is ballparked at >$700,000.

Existing Conditions

• The proposed approach integrates a Deep Energy Retrofit with distributed HVAC.• It includes:

- Skirt the slab-on-grade with 3 inches foam insulation- New quad-glazed Serious Materials windows- New sheathing used as the air barrier- 6-1/2 inches of added exterior rigid foam and new wood cladding- Room-by-room H/V - a residential energy recovery ventilator and a -minisplit heat pump

The Proposed Fix

3” PerformGuard

3” Polyiso beneath3-1/2” Nudura EPSpanels with integral1x nailers

SPF at eave

Windows inTimberStrandextension bucks

Serious Windows

Mitsubishi Hyperheat3 ton unit, two indoor unitsRated to -13FOversized for this application

One of two indoor units

Perforated fabric duct

Renewaire EV200 energy recovery ventilator175-180 CFM as installed - 10 CFM/person151 Watts85% effectiveness (measured at -3F outdoor

air temperature and 70F indoor airtemperature)

Demand controlled via CO2

Measuring…

Heat pump kWh

ERV kWh, elapsed time, run time

Indoor and outdoor temperatureRelative HumidityCO2

Also on-off for lights and ERV

Early data (eyeballed)• From January 8th through February 8th, energy into the heatpump was 125 kWh (about $18) during temperatures ranging from-1F to 52F, 1,373 HDD65F• Indoor temperatures ranged from 65F during setback up to 73.5Fduring occupied hours• Indoor RH during occupied hours ranged from 23% to 44%,usually in the mid-30s• CO2 ranged from 800 - 1,200 ppm during occupied hours• ERV run hours averages 33 hours/week• Lights on 25-26 hours/week• Lighting (w/OS) at 0.8 W/sf may be higher annual load thanheating

Wed Thu Fri Sat Sun Mon Tue Wed

Advantages of the DER Approach• Scalable and phase-able - can do one or many classrooms - modularequipment• >2/3 reduction in design heat loss• Possible 10X reduction in annual energy cost• No combustion• Electrically driven heat pumps compatible with renewable energysources• Individual room control - comfort and ability to use rooms in off-hours• Demand controlled ventilation is easy to implement• A long time constant in the event of a power failure• No third party controls

Plainfield School Facilities CommitteeMike Higgins

Bill Knight

Allan Ferguson

Shawn Rogers

Thom Wolke

Marc Rosenbaum