Walden Pond Visitor Center

Walden Pond State Reservation is an internationally acclaimed National Historic Landmark and protected open space along 330 acres. Over 500,000 visitors a year visit the pond due to its great beauty, as well as inspiration of Henry David Thoreau. The surrounding towns of Concord and Lincoln are the fonts of the flowering of American literature in the mid-nineteenth century, as well as the birthplace of the modern conservation movement.

The 5,575 sf visitor center interweaves with the landscape in order to emphasize the pond and heighten the experience of the site. The building is nestled behind trees and shrubs giving it an air of mystery with a long accessible ramp to draw visitors into the visitor center. Exhibition spaces, a community meeting room and staff offices, create a new hub. A large open-air deck of locally-source heat treated ash with a black locust trellis, addresses the pond and provides a moment of repose at the building’s entry.

The structure is an all-electric, net-zero consumption building and implements Passive House principles. The building has no reliance on fossil fuels. In winter, high-performing triple-pane windows and super insulation keep the heat in. In warmer weather, ample operable windows and ceiling fans create natural ventilation and light, thus reducing the need for air conditioning and artificial lighting. A large solar array provides shade over the parking lot and services all the energy needs of the building. The walls and floors of the building are from locally sourced heat-treated wood to withstand the New England weather, eliminating the need for rainforest wood. 

Quick Facts

General

Location
915 Walden St.
Concord, MA01742
United States
Building Type Visitor Center
Project Type Net Exporter
Basis of Performance Claim Modeled, Verified,
Bedrooms 0
Conditioned Floor Area 4 500

Energy Summary

Energy Data Type Measured,
Renewable Energy System Type(s) Photovoltaics,
Ratings
Annual renewable energy generated 103 224

Envelope and Mechanicals

Subslab assembly

Foundations were cast-in-place concrete with a continuous vapor barrier and 2" of rigid insulation.

Foundation wall assembly

Foundation walls are cast-in-place concrete with 3" continuous insulation down to the footing, waterproofing layer and drainage board leading to a footing drain.

Above grade wall assembly

2x6 wood framing at 16" o.c. with full cavity cellulose insulation. 1/2" plywood sheathing installed over studs with additional 3" continuous insulation. An additional layer of 1/2" plywood was installed and then building felt and wood siding with a ventilation mat.

Door Assembly

Same as above.

Air Changes per hour, ACH50

Project Team:

Architect

Other Team Members:

Owner:
Massachusetts Department of Conservation and Recreation:
Leo Roy, Commissioner
Priscilla Geigis, Director of State Parks
Susan Hamilton, North Region Manager
Pete Hoffmann, Field Operation Team Leader
Robin Pfetsch, Project Manager
Nat Tipton, Assoc. Project Manager
Stephen Brown, Solar Project Manager

Construction partners:
Massachusetts Division of Capital Asset Management and Maintenance:
Carol Gladstone, Commissioner
Jack McDermott, Project Manager
James Styles, Project Engineer
Frank Lorenzo, Resident Engineer

Architect:
Maryann Thompson Architects
Principal: Maryann Thompson FAIA
Project Manager: Zac Cardwell AIA LEED AP
741 Mount Auburn Street,
Watertown, MA
617-744-5187
www.maryannthompson.com

Engineers:
Structural: RSE Associates Inc.
MEP/FP: Garcia, Galuska & DeSousa, Inc.
Civil: Nitsch Engineering

Design team:
Masterplanning: Crosby | Schlessinger | Smallridge
Landscape Architecture: Michael Van Valkenburgh Associates, Inc.
Specifications: Kalin Associates Inc.
Code: Hughes Associates
LEED: The Green Engineer, Inc.
PV Canopy Design and Engineering: Solar Design Associates, LLC
Cost Estimating: VJ Associates
Exhibit Planning: Object Idea

Construction team:
General contractor: Stutman Contracting Inc.
Solar Array contractor: Ostrow Electric Co.

Ratings:

Awards:

Completion

Completion Date: Friday, September 16, 2016

Scope

100% new construction (partial reused basement from previous building). Scope included building and extensive landscaping, utility and energy components.

Type of Construction New,
Number of buildings 1
Floor area of each building 5 575
Bedrooms 0
Stories 1
Conditioned Building Volume 55 000
Conditioned Floor Area 4 500

Location and Climate Details

Visitor Center

Address
915 Walden St.
Concord, MA01742
United States
Location Type Suburaban
Climate Region Zone 5
Köppen Climate Type Cfa
Lat. / Long. POINT (-71.3345107 42.4404591)
Elevation 205
Solar Insolation 4.378 kWh/m2/day
Annual CDD and Base Temp 867 | 65 deg F
Annual HDD and Base Temp 6372 | 65 deg F

Site

Site Conditions:

previously developed land, preexisting structure(s),

Site Description:

The site is across Walden St. from Walden Pond in the location of a previous structure (former house) used by DCR as a visitor center and adjacent to the visitor parking areas. An enhanced arrival landscape area was created between the parking area by reducing the overall parking lot size from the existing to better connect and welcome visitors to the new Visitor Center, Henry David Thoreau replica cabin and crosswalk to the pond itself.

Monthly Energy Data and Utilities

Energy Data Type: Modeled, Verified,

Electric Utility: Concord Municipal Light Plant

Gas Utility: N/A

Renewables and Energy Balance

Renewable Energy Sources:Renewable energy is generated on-site but not on the building (e.g. wind turbine in the parking lot),

Renewable Energy System Description & Details: Within the main parking area of the park is a RBI Parking Canopy Array with 336 qty Upsolar 315W modules - each w/ module-level DC optimizers, feeding 8 qty Solaredge SE11400A-US inverters. These are arranged on two equal-sized carport structures, single 5 degree tilt each. Azimuths 6 deg & 27 deg East of True South.

Annual renewable energy generated 103 224
Annual Renewable Energy Generated Data Type Measured,
Power Rating 105 840Watts
Renewable Energy System Type(s) Photovoltaics,
Source of Annual Production Data PV production numbers were measured from array meter data October 01, 2016 through September 30, 2017 and represents PV array gross production.

Walls and Roof

The walls are typical wood framed with cavity insulation. An additional layer of continuous exterior insulation was provided on the outside of the wall framing. The roof was constructed of SIPs. Below grade foundation walls and slab had continuous insulation with full basement areas having an additional interior insulation layer. Basement/crawlspace ceilings were insulated as well. A high performing triple-paned window/door system was installed for openings.

Subslab assembly

Foundations were cast-in-place concrete with a continuous vapor barrier and 2" of rigid insulation.

Subslab R-value 10.00
Slab edge assembly

The edge of the slab consists of a 1" thermal break fully insulated.

Slab edge R-value 5.00
Foundation wall assembly

Foundation walls are cast-in-place concrete with 3" continuous insulation down to the footing, waterproofing layer and drainage board leading to a footing drain.

Foundation wall R-value 15.00
Above grade wall assembly

2x6 wood framing at 16" o.c. with full cavity cellulose insulation. 1/2" plywood sheathing installed over studs with additional 3" continuous insulation. An additional layer of 1/2" plywood was installed and then building felt and wood siding with a ventilation mat.

Above grade wall R-value 39.30
Cathedral ceiling assembly

N/A

Cathedral ceiling R-value

Windows and Doors

Window Assembly:

European Larch windows by Buildau and Bussmann. Triple pane glazing. Mix of hoppers, casements and fixed windows. Sliding and swing doors.

Door Assembly:

Same as above.

Average window U-factor 0.17
Door U-Factor 0.17
Door Area 167

Mechanical Systems

Space cooling - Manufacturer & Model Mitsubishi PKFY-P08NHMU-E2 (3 units), Mitsubishi PKFY-P06NBMU-E2 (1 unit), Mitsubishi PKFY-P12NHMU-E2 (4 units), Mitsubishi PKFY-P18NHMU-E2 (2 units), Mitsubishi PLFY-P12NBMU-ER2 (1 unit), Mitsubishi PEFY-P36NMAU-E2 (1 unit), Mitsubishi PUMY-P36NHMU Condenser (1 unit) , Mitsubishi PUMY-P60NKMU Condenser (2 units),
Space heating - Manufacturer & Model Mitsubishi PKFY-P08NHMU-E2 (3 units), Mitsubishi PKFY-P06NBMU-E2 (1 unit), Mitsubishi PKFY-P12NHMU-E2 (4 units), Mitsubishi PKFY-P18NHMU-E2 (2 units), Mitsubishi PLFY-P12NBMU-ER2 (1 unit), Mitsubishi PEFY-P36NMAU-E2 (1 unit), Mitsubishi PUMY-P36NHMU Condenser (1 unit) , Mitsubishi PUMY-P60NKMU Condenser (2 units),
Domestic hot water - Manufacturer & Model AO Smith - Sun-80
Domestic hot water - capacity 80
Ventilation - Manufacturer & Model RenewAire EV450IN,
Lighting Manufacturer and Model All LED fixtures by the following manufacturers: Tech Lighting, Beta Calco Inc., LaMar Lighting, Juno Lighting, Nora Lighting, Bega,
Lighting Efficiency 0.6 w/sf,
Mechanical Equipment Installation Details and Comments

During the course of construction QA/QC was undertaken through periodic review of installation by system designers. Upon system installation fundamental commissioning was undertaken to ensure that systems performed as designed.

Envelope

Air Changes per hour, ACH50
Air Changes per hour, CFM50

General Process

Design for Adaptability:

Software Tools

Software Tools:

AutoCAD (construction drawings); Sketchup/Rhino (3D modeling)

General modeling information:

Carrier Hourly Analysis Program (HAP) v5.00

Lessons Learned

Outcome of Project Goals:

Discrepancies:

Rebates and Financial Incentives

Federal incentives

None

Local incentives

None

State incentives

Visitor Center - two grants were obtained from MA DOER. One grant, totaling $130,850, funded certain components to fulfill the net-zero design including R-60 roof insulation, R-40 wall insulation, 0.20 U-Value triple-paned windows, LED automated lighting systems, and low flow plumbing fixtures. The other grant totaling $125,000, funded renewable thermal components including a Mitsubishi 12-ton VRF heat pump system and a solar hot water system.

Solar PV array - two grants were obtained, totaling $59,720. One $52,920 grant for the solar PV array was obtained for DOER that covered the construction costs of the canopy, A second grant from the Massachusetts Department of Environmental Protection for $6,800 assisted with the cost of two dual-head Electric Vehicle (EV) charging stations.

Utility incentives

A credit of $3,200 was applied to the Walden Visitor Center electric bill by Concord Municipal Light Plant.

Other incentives

None

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