The new Yew Dell Botanical Gardens Visitor Center is a 1, 842 s.f. facility located on a 43 acre nursery founded in 1943 by horticulturalist & nurseryman Theodore Klein. The historic property, recognized for its unique collection of themed structures and gardens, is part of The Garden Conservancy, a national organization dedicated to saving and preserving America’s exceptional gardens. Funded in its entirety by a private donor, the project entails the rehabilitation of an existing tobacco barn situated near the property’s entry. The program includes: reception area with information & ticket sales, gift shop, plant sale area, group tour meeting zone, internet sales office, and storage.
Several key challenges guided the project: 1) a modest construction budget of $64/s.f., 2) a tight 5-month design & construction completion schedule coinciding with a large annual garden celebration/fundraiser event, and 3) the architect’s proposal to house the client’s ambitious program in an existing structure with limited available space.
Preserving the exterior iconic image of the tobacco barn structure in its entirety, the new facility is designed as a ‘building-within-a-building’. For economy and energy efficiency, the project utilizes the shell of the existing barn as an independent shade structure, leaving the barn unaltered with the exception of minor framing stabilization. Working within the existing structural bays, new conditioned interior spaces are consolidated to one side of the barn interior while the opposing unconditioned space acts as a covered flexible-use area. During low-humidity spring & fall seasons, frameless glass doors are left open to merge both halves of the barn’s interior. Following Federal historic preservation guidelines, new construction is clearly differentiated from the existing structure through light-colored interior wood plank surfaces and material contrasts.
The use of light – both natural & artificial – is a key design element that transforms the facility throughout the day, affecting the transparency and visibility of the various programmatic components while amplifying the rustic characteristics of the existing tobacco barn. Acting as either a mirror or a transparent boundary depending on the viewing angle, tempered glass walls reflect & refract sunlight, views, and outer barn walls, emphasizing a sense of spaciousness while allowing the original barn interior to visually register. During the evening, the facility becomes a lantern glowing from within the gardens. The exterior of the barn is highlighted by interior light filtering through gaps between the existing wood planks.
A conventional palette of materials, including milk-painted tongue & groove wood siding, tempered glass, and sealed concrete floors, is detailed with an eye toward simplicity and precision.
TYPE OF CONSTRCTION, MATERIALS & MECHANICAL SYSTEMS
Building Construction [Exterior Envelope]: Preservation of existing tobacco barn (minor framing stabilization), freestanding wood framing, closed-cell insulation, gypsum board, sealed concrete slab on grade with rigid insulation lining, tempered glass, painted steel structure, milk-painted tongue & groove pine siding.
Finish Materials [Interiors]: Milk-painted tongue & groove pine planks, MDF slat-wall panels, sealed concrete, tempered glass, translucent film, painted steel.
Mechanical Systems: Natural ventilation, high efficiency ducted heating & cooling and a balance of natural & artificial light.
CONSIDERATION OF ENERGY EFFICIENCY
The project focused on the challenges of maximizing the value of a modestly-funded project for a not-for-profit client, while incorporating affordable, passive sustainable strategies. Simple strategies include the following:
• Re-using the shell of the tobacco barn as an independent shade structure, reducing heating & cooling loads while preserving the historic structure
• Arranging programmatic components to maximize use possibilities through flexibility of indoor, outdoor and sheltered areas
• Consolidating the area of conditioned space to a minimal 620 s.f.
• Maintaining pervious gravel paving beyond the barn footprint to avoid increasing stormwater runoff
• Minimizing ‘Heat Island Effect’ through high solar reflectance index (SRI) of roof & site materials
• Using of high fly ash content in concrete mix (recycled content)
• Using pre-fabricated kit-of-parts and modular materials to minimize construction waste
• Minimizing the amount of material types to ease maintenance; choosing durable, easy to clean materials
• Sourcing the majority of construction materials either locally or from within a 500-mile radius of the project site