Citation Award Winner
Design Team Member(s)
Ed Gulick, High Plains Architects – Lead ArchitectAlex Tyler, High Plains Architects – Media Lead
When the SxS Group set out to develop a building for their own offices as well as commercial tenants, they desired the qualities of a historic building, the environmental performance and low operating costs of a LEED Platinum-certified green building, and a daylit, loft-like interior that would serve as a comfortable home-away-from-home. The two-story, 6,100 sq. ft. brick building is located on the north edge of Bozeman, offering expansive views of the Bridger Mountains to the north. With its parking at the rear and small setback at the front, the project provides a model for pedestrian-oriented design in future development in this emerging neighborhood.
The second floor of the SxS Building has offices for the building owner’s business and small commercial tenant space. The flexible first floor plan accommodates one to three commercial tenants in a few potential configurations.
• Reset the neighborhood’s emerging character with a building designed for bicycle and pedestrian transportation. • Provide sufficient daylight to regularly occupied spaces so that artificial lighting is not required on clear days. • Set building up to be net zero energy in the future; no natural gas service is provided to the building. • Reduce energy from the grid compared to the 2012 energy code by at least 40% through the combination of energy efficiency and a 6.4 kW rooftop solar array. 43% less grid energy achieved. • Reduce interior water use by 45% compared to the building code through plumbing fixture efficiency. 46% achieved. • Eliminate the need for an irrigation system with drought-tolerant plantings. • Achieve LEED® Platinum certification. Accomplished
The muse for the project was a historic fire station that has been repurposed as offices; the two storefront sections on the front are imagined as infill for the original apparatus bays. Providing all the spaces with abundant daylight was a primary consideration to not only dramatically reduce energy use for artificial lighting but also create a highly desirable, productive occupant experience. Daylight is projected deep and evenly into the first-floor tenant spaces with exterior light shelves (white on top) that reflect daylight onto the 12-foot high ceilings. In addition to exterior light shelves, the second floor has operable skylights to provide daylight as well as excellent natural ventilation, and the offices can be cooled largely through night flushing in the summer. The lofty spaces on the second floor have exposed glulam beams, and relites in partition walls provide views and daylight to interior spaces. Behind the brick is a superinsulated building envelope, featuring 2-3X as much insulation at the roof, walls, and slab as the energy code. The design has virtually no thermal bridging and is very tight; blower door testing has verified that air infiltration is less than 1.0 air change per hour (ACH50), about 4X better than the energy code. The location and size of the windows openings also significantly reduce heating and cooling loads, and the variable refrigerant flow (VRF) heating and cooling system and heat recovery ventilator (HRV) fill the remaining needs efficiently.
SxS’s Indoor Environmental Quality Strategy is as follows: 1) Minimize air pollutants in materials through source control. All of the materials in the building were selected to minimize air emissions, such as: low-VOC and zero-VOC (volatile organic compound) adhesives, sealants, paints, and coatings; rubber flooring with minimal emissions for the stair landings; and MDF trim and composite wood with no added urea formaldehyde for the cores of doors and cabinets. 2) Minimize dust through source control. Walk-off mats at each of the entrances are long enough to remove most of the dirt on the bottom of shoes, which is the route that 90% of dust enters buildings. 3) Minimize air pollutants in cleaning products through source control. Cleaning products are often a major source of indoor air pollution. The Green Housekeeping program of Exec U Care Services, Inc. uses Green Seal certified products with minimal amounts of VOCs (volatile organic compounds). 4) Provide daylight and views outside. Beyond reducing energy use, daylighting also has some significant human productivity benefits: a study has found that students scored 8-18% better on standardized tests in buildings with high levels of daylight compared to students in schools with little or no daylight. And workers were found to have better memory retention in buildings that have windows with views to nature. 5) Provide natural ventilation with operable windows. Similar to daylighting, there are human productivity benefits for natural ventilation in addition to the energy benefits. According to various studies, there is a 1-11% increase in productivity in spaces where occupants can control ventilation, and the comfort zone for occupants expands when there are operable windows. Correction: diagram states R-20 code minimum Roof Insulation (replace with R-30)
How this design minimized the demand for energy: a) Orient the buildings to take optimal advantage of solar geometry. While the site dictated that the building be almost square in plan, the windows on the south and north facades are sized to maximize winter solar gain when supplemental heating is desirable, minimize summer solar gain when it is not desired, and maximize daylighting throughout the year. Windows on the east are small, as low angle sunlight from the east causes glare and high summer solar gain. There are no windows on the west, which, like the east façade, would have brought undesirable glare and summer solar gain. b) Super-insulated building envelope. Walls have high levels of insulation (about R-38.5 on the south wall and R-43.8 on the other walls) and very little thermal bridging; roof assemblies have levels of insulation (R-70.5) of continuous insulation; floor assemblies are similarly highly-insulated; and windows have very low thermal transmission and high visible light admittance. Finally, blower door tests were used to ensure that the building envelopes are very airtight, minimizing air infiltration can lead to substantial heat loss. c) Maximize daylighting. In typical office buildings in the U.S., 30% of the energy is used for artificial lighting. The combination of light shelves with clerestory windows, skylights, and view windows provides enough daylight to reduce energy for artificial lighting use by 63%. d) Maximize natural ventilation. The combination of relatively low operable windows and operable skylights up high induce a stack effect they are opened in the building. Anytime the temperature differential from top to bottom is greater inside than on the outside, air is exhausted passively, while breezes provide cross ventilation whenever windows at any level are open across each other. In the shoulder seasons of spring and autumn, natural ventilation alone can typically ventilate and cool the building. During the heat of the summer, night ventilation is employed to cool the building mass before closing the building up mid-morning, minimizing the need for mechanical cooling. e) Provide exposed thermal mass. By moderating temperature extremes inside, the thermal mass of the first floor concrete slab reduces peak loads on the mechanical systems, allowing them to be downsized. The Water Strategy is as follows: 1) Reduce water demand: Highly efficient 0.8 gallon per flush (gpf) toilets are installed throughout building and the 1.5 gpm showerhead uses 40% less water than the conventional counterpart. The result of these measures is a reduction in interior water use by over 45%, while drought-tolerant plantings have eliminated the need for a permanent irrigation system.