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EMERALD PEOPLE’S UTILITY DISTRICT HEADQUARTERS, 1987-1988

The Emerald People’s Utility District (EPUD) Head­quarters, an office and warehouse complex, was built for a small public utility company in the cool and rainy climate of Eugene, Oregon, in the Pacific Northwest United States. The design vigorously incorporates daylighting and pas­sive strategies for heating and cooling. The site arrange­ment was governed by ecological sensitivity to the surrounding wetlands and neighboring small industries. The complex is united by a desire to highlight the qualities of both the outdoor and indoor environments.

Eugene, Oregon

Equinox Design and WEGROUP Architects and Planners

Figure 11.18 South elevation of EPUD Headquarters. Note the elongated axis, the clerestory windows, and the deciduous shading. (Photograph cour­tesy of John Reynolds.)

TABLE 11.5 Fact Sheet

Project

Building Name

Client

City

Lat/Long/Elev

Emerald People’s Utility District Headquarters Emerald People’s Public Utility District Eugene, Oregon 44.01N 123.02W, 460 ft (140 m)

Team

Architects

Mechanical Engineer Daylighting

John Reynolds (Equinox Design) and Dick Williams (WEGROUP Architects and Planners) Dave Rogers Virginia Cartwright

General

Time Line Floor Area Occupants Cost

1995 Cost in US$

Stories

Plan

1987-1988.

24,255 ft2 (2252 m2) (office only).

40.

$4,123,600 (entire complex).

$5,313,918.

One – and two-story office buildings with warehouse and vehicle storage.

Courtyard footprint. Two story wing is 122 ft by 60 ft, east-west one-story wing is 98 ft. by 60 ft. Overall plan including courtyard is 167 ft. by 160 ft.

Site

Site Description Parking, Cars

A former horse pasture located just outside Eugene near the Willamette River and bordered by paved roads and light industry. Buildings are elongated along the east-to-west axis and sited to preserve the existing small creek and bordering wetlands.

104 cars, plus utility vehicles.

Structure

Foundation Vertical Members Horizontal Spans

Slab on grade.

Load-bearing concrete block exterior fin walls and interior bearing walls at 24 ft on center.

Precast concrete beam on 24 ft bays running north to south. Hollow-core concrete slab floor and roof spans.

Envelope

Glass and Glazing

Skylights

Cladding

Roof

Clear double-glazed, 38 in. airspace, non-thermal break aluminum, overall U = 0.74.

None.

4 in. concrete block outside, 1 in. airspace, R-19 batt insulation in metal studs at 24 in. o. c., gypsum board inside, corrected R = 11.9, therefore U = 0.084.

R-40 insulation over concrete slab, corrected U = 0.028.

HVAC

Equipment Cooling Type Distribution

Duct Type Vertical Chases

Split system.

Direct expansion.

Main system is variable air volume (VAV). A separate 2 ton heat pump serves the computer room and a 1.2 ton heat pump serves the dispatch room because of their longer hours of occupancy schedule. Individually operated electrical resistance heating units are under windows.

Rectangular ducts furred above circulation paths.

None.

Interior

Partitions

Finishes

Vertical Circulation

Furniture

Lighting

Load-bearing concrete block in 24 ft wide bays spanning horizontally east to west Carpeted floors, exposed concrete ceilings, gypsum walls.

One central elevator plus stairs at east and west ends.

Each workstation is located within 20 feet of a perimeter window.

North and south daylighting and indirect fluorescent artificial lighting.

Courtyard footprint. Two story wing is 122-ft by 60-ft, east – west one story wing is 98-ft. by 60-ft. Overall plan including courtyard is 167-ft. by 160-ft.

Precast concrete beam on 24- foot bays running north to south. Hollow core concrete slab floor and roof spans.

R-40 roof insulation over concrete panel, corrected U = 0.028

Clear double glazed windows and clerestory, 3/8-in. airspace, nonthermal break aluminum, overall U = 0.74

Load bearing concrete block exterior fin walls and interior bearing walls at 24-ft on center. 4-in concrete block outside, 1-in. airspace, R-19 batt insulation in metal studs @ 24-in. o. c., gypsum board inside, corrected R = 11.9, therefore U = 0.084.

Rectangular ducts furred above circulation paths.

Acoustical baffles

Carpeted floors, exposed concrete ceilings, gypsum walls.

Each workstation is located within 20 feet of a perimeter window.

Trellis shade over clerestory and south windows

North and south daylighting and indirect fluorescent artificial lighting.

Slab on grade foundation

Main HVAC system is Variable Air Volume, VAV. Individually operated electrical resistance heating units are under windows.

Program

Client

In October 1970 a small group of rural Eugene residents were brought together by their concern over rising electri­cal rates. The price of energy from their investor-owned utility company was close to double that of surrounding areas served by publicly owned utilities. Discussions led to further meetings with state officials, and the effort to cre­ate their own public utility district was initiated.

It was to be a long struggle. But after 13 years and 14 court cases, the time-consuming and expensive battle was won. The group set out to raise $49 million in bond rev­enues and purchased the local facilities of the investor util­ity. The switchover from private investor utility to publicly owned Emerald People’s Utility District was celebrated victoriously on November 17,1983.

Institutionally, EPUD fashions itself as a public service organization, working for the benefit of its service area. Customers are thought of as co-op members of the EPUD community more than as ratepayers. The utility now hosts luncheon tours of its facility, contracts youth groups to wash its service trucks weekly, hosts community functions free of charge, and runs a number of energy information and conservation programs. There is even an EPUD Internet provider service.

EPUD’s operating budget includes about 33 percent power purchasing, 22 percent operations and mainte­nance, 23 percent for debt service, and 20 percent for con­struction, equipment, and conservation programs. Although 80 percent of the power it purchases still comes from the utility it bought out, EPUD can now resell it at cost to its “members.” The remaining power comes from increasingly green sources: 6 percent from certified green power producers and 5 percent from EPUD’s own Short Mountain methane power plant, which operates on gas produced from waste in a landfill.

Brief

Several rounds of meetings and group discussions were held between the design team and the client group to jointly develop a program for the new headquarters build­ing. Several points were established:

• Sensitivity to the site, its trees, and nearby streams

• Attractiveness to customers coming to the center to pay bills and attend functions

• Use of the building by customer organizations as a public facility

• Group spirit among staff members and in the work­place

• Prudent use of energy and promotion of energy con­servation

• Use of renewable resources to minimize energy con­sumption

Site

A location for the building was selected along a highway south of Eugene and Springfield. The site is east of the road and separated from it by railroad tracks and feeder streets, a roughly football-shaped area between two existing highway feeder roads. Open pastureland and a small creek lie further to the east, bordering a large wetlands area. The EPUD plot was formerly a horse pasture in an immediate neighbor­hood consisting of sparse light industry and residences.

Climate

The Willamette River Valley of western Oregon is bound­ed by the Cascade Mountains to the east and the Coast Range to the west. The state’s three largest cities are locat­ed in the valley: Portland, Eugene, and Salem. North of Eugene the valley broadens, but to the south it is almost closed in by low hills. This southern end of the valley is where EPUD and its service district are located, the sharp end of a V opening up all the way to Seattle. The region’s landscape is one of mixed grassland savanna and open woodland consisting of Douglas fir, oaks, broadleaf decid­uous species, incense cedar, and a few remaining stands of ponderosa pine.

The Coastal Range blocks off most of the fog from the Pacific, but storms cross it easily. Three openings to the ocean bring cool air into the Willamette Valley: the Van Duzer corridor from Lincoln City on the coast to Salem in the valley, one from Newport to Corvallis, and one from Florence to Eugene. The Cascade Range, on the other hand, fends off all but the strongest continental air masses from the east. When air does flow into the valley over the Cascades, it brings hot, dry summer weather or clear win­ter days with frosty nights. Numerous small creeks and low-lying areas of moisture produce considerable fog.

The climate is generally moderated by maritime Pacific air. Its cool, wet winter and mild, dry summer cli­mate is favorable to wine growing, particularly the early ripening Pinot noir grape. There are currently more than 210 wineries in the Willamette Valley, cultivating 6300 acres of vineyard. Summer growing seasons are enhanced by long sunlight hours, up to 15.3 hours at the solstice, and cool nights. The weather is similar to that in the Mediterranean climates of California, but Oregon winters last longer and are colder. Long periods of severe heat or cold, however, are uncommon here. Not surprisingly, normal temperature ranges are narrow. The daily aver­

ages in January are a 67°F high and a 33°F low, in July 82°F and 51°F. Overall, temperatures are generally on the cool side; there are 4701 degree-days heating to only 248 cooling. Bin data of hourly temperature observations shows that 1.7 percent of the annual hours in Eugene are hot (above 85°F), 4.8 percent are warm, 10.1 percent comfortable (65°F to 75°F), 22.3 percent are cool, and 61.1 percent are cold (below 55°F). Less than 5 percent of all hours are below freezing.

Rainfall distribution follows a cyclical curve that peaks in December and January and bottoms out in July and August. The winter months have 20 or so rain days and about 8 in. (200 mm) of rain each, whereas the summer months have almost no rain at all. About 50 percent of the annual rainfall occurs in December and January. Regionally, rainfall increases with elevation and with proximity to the coast. Portland, at 21 ft above sea level, receives 37.4 in., and Salem (196 ft) gets 40.4 in. Eugene (359 ft) receives 46.0 in. The EPUD site, in the hills south of Eugene, is at 460 ft elevation.

In regard to daylighting objectives, sky cover data shows marked differences in seasonal availability of natu­ral light. Overcast conditions are prevalent November through February, whereas June through September skies are mostly clear. Equally important, winter days at this lat­itude are only 8.7 hours long at the solstice, and summers days last up to 13.5 hours.

Intention

Design Team

Collaborators on the Emerald project included architect John Reynolds, principal of Equinox Design and known as

table 11.6 Normal Climate Data for Eugene, Oregon

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Dec.

Year

Degree-Days Heating

777.4

602.6

574.4

442.3

295.2

134.9

36.9

32.7

111.5

360.5

585.6

747.6

4701.4

Temperature

Degree-Days Cooling

0

0

0

0.1

4.5

28.4

95.1

87.3

32.1

1

0

0

248.5

Extreme High

67

72

77

86

93

102

105

108

103

94

76

68

108.0

Normal High

46.0

51.0

56.0

61.0

67.0

74.0

82.0

82.0

77.0

64.0

53.0

47.0

63.0

Normal Average

40.0

43.0

46.0

50.0

56.0

61.0

67.0

67.0

62.0

53.0

45.0

41.0

53.0

Normal Low

33.0

35.0

37.0

39.0

43.0

48.0

51.0

51.0

48.0

42.0

38.0

35.0

42.0

Extreme Low

-4.0

-3.0

20.0

27.0

28.0

32.0

39.0

38.0

32.0

19.0

12.0

-12.0

-12.0

Dew Point

36

38

39

42

46

50

52

52

49

46

41

37

44.0

Humidity

Max % RH

91

92

91

88

84

81

78

82

89

94

93

92

88.0

Min % RH

80

72

64

58

54

49

38

39

44

61

79

84

60.0

% Days with Rain

66.0

65.3

67.4

60.7

47.5

36.6

16.8

21.4

30.3

46.7

69.0

69.7

49.5

Rain Inches

7.9

5.5

5.3

3.1

2.3

1.4

0.5

0.9

1.4

3.6

7.5

8.3

47.8

Sky

% Overcast Days

69.7

62.9

56.3

50.2

41.9

37.7

21.4

23.8

27.4

46.3

66.6

72.8

48.1

% Clear Days

8.9

10.5

11.6

13.5

17.6

23.7

41.1

38.1

21.0

7.5

5.9

20.7

18.3

Wind

Prevailing Direction

S

S

S

S

N

N

N

N

N

S

S

S

N

Speed, Knots

9

9

9

8

8

9

9

9

9

7

9

9

9.0

Percent Calm

10.9

10.6

7.6

8

9.2

8.9

8.6

10.6

11.6

13.8

11.8

11.8

10.3

Rain

19.9

19.7

20.3

18.3

14.3

11.0

5.0

6.4

9.1

14.1

20.8

21.0

180.7

Days Observed

Fog

17.7

16.2

10.8

7.4

5.7

4.6

2.4

4.7

10.4

19.6

20.8

19.7

140.7

Haze

7.0

7.3

4.7

3.1

2.0

1.6

1.6

4.5

9.8

12.7

8.7

6.3

69.9

Snow

4.5

2.6

2.2

0.7

0.06

0

0

0

0

0.06

0.9

2.8

14.1

Hail

0

0

0.031

0.1

0.03

0.09

0

0.03

0

0.03

0

0

0.3

Freezing Rain

0.24

0.06

0

0

0

0

0

0

0

0

0

0.1

0.5

Blowing Sand

0

0.03

0

0

0

0

0

0

0

0

0

0

0.0

RAIN

3 – – SNOW

BLOWINGSAND

-FOG

HAIL

HAZE

—9———— FREEZINGRAIN

Figure 11.21 Climate analysis graphics.

the coauthor of Mechanical and Electrical Systems for Buildings. He is also professor emeritus of the architecture faculty at the University of Oregon. Rounding out the design team was Dick Williams of WEGROUP Architects and Planners. Virginia Cartwright served as daylighting consultant.

philosophy

In sympathy with EPUD’s grassroots ideals and publicly operated enterprise, the philosophy of the project team included a large measure of environmental and social con­sciousness. Given their collective background, the design­ers and consultants were well suited to EPUD’s mission.

Intent

This headquarters and operations facility would be a clear statement about EPUD’s commitment to energy conserva­tion and prudent use of resources. This goal was already programmatic, based on the client’s brief and the develop­mental meetings. So the design team set out to optimize the use of the site and its relationships with the building. One objective, for example, was to provide a prolonged pleasant walk across the site from the parking areas. Another was to make it possible for the occupants to appreciate the site from the working environment. Finally, and perhaps most important, there was the intention of using passive energy systems to provide for interior comfort levels.

Figure 11.22 Bin data distribution for Eugene. Concentric areas of graph indicate the number of hours per year that weather conditions normally occur in this climate. Similar to elevation readings on topographic maps, highest frequency occurrences of weather are at the center peaks of the graph. (Data sources: Engineering Weather Data, typical meteorological year (TMY) data from the National Climatic Data Center, and the ASHRAE Weather Data Viewer from the American Society of Heating, Refrigerating and Air-Conditioning Engineers.)

Critical Technical Issues

Inherent

Aside from the office headquarters, the new facility would also need a warehouse, truck storage, and parking for customers, staff, and administration.

Part of the office building would be used 24 hours per day for emergency response dispatching.

Contextual

Although the building was to reflect a corporate image of responsibility, it also needed to have a low – key, grassroots character.

The site was to provide a natural setting for the build­ing, despite the surrounding highway, light industry, and railroad tracks.

Wetlands to the east of the site were to be respected.

The design problem centered on the unity of site and building, climate, and environment.

This building, like other open-envelope, highly glazed buildings that visually unify the interior with the exterior, was also thermally weak in terms of insula­tion value.

The cool and gray Eugene winter days and the long, dry summer days made opposite demands on the design.

Appropriate Systems

It soon became evident to the team that daylighting com­bined with passive solar heating strategies would be essen­tial to the environmental scheme of the building. Lighting requirements would be substantial in the office work­spaces, which suggested natural daylighting. The Oregon winter dictated passive solar heating. What was not certain was exactly how the need for extensive daylight apertures, in relation to winter heat loss, would be met. Further, how would summer solar heat gain be warded off? Careful ori­entation proved to be the solution for most of these ques­tions, with a well-integrated use of thermal mass for both heating and cooling. The design, as built, now uses 50 per­cent of the energy consumed by comparable buildings in the same climate.

Precedent

For precedents, the architects relied most on the compila­tion of previous works that are represented in the stan­dard text of Benjamin Stein and John S. Reynolds, Mechanical and Electrical Equipment for Buildings. Making use of precedent begins with scrutinizing work that is simultaneously general to the field and pertinent to the architect’s own progress of works. The architects cite one particularly influential reference, elementary school class­room wings of the 1950s with daylighting from both sides and cross ventilation.

The team also took inspiration from the traditional courtyard as an organizing theme for the EPUD head­quarters. Reynolds says of his most recent book, Courtyards: Aesthetic, Social, and Thermal Delight (2001), “It’s my homage to ‘firmness, commodity, and delight’.”

Site

Figure 11.23 Site plan of EPUD.

The 167 ft x 160 ft (50.9 m x 48.8 m) footprint of the head­quarters building was broken into two wings to provide extra wall exposure to the north and south. A smaller one – story structure, the engineering wing, sits to the south, with
a roof sloping down northward into the courtyard at an angle calculated to admit the winter sun to the open space. A two-story customer services wing forms the north side of the court. The two wings are connected by a central meet­ing hall and a smaller north-to-south block of the building. Between them is a semiprotected courtyard that provides views from the interior and a last step in the entry sequence.

Parking is intentionally pulled away from the building to extend this entry sequence. Customer parking is closest, but still isolated from the entry doors by the depth of the courtyard, the single story wing, and landscaping. Staff parking is at the far northwest end of the site. From either location, a short jaunt across the site is meant to accentu­ate the natural setting. In inclement weather it also allows appreciation of the differences between inside and out. A covered walkway along the west side of the courtyard offers protection and a semienclosed stage of the entry sequence.

The east half of the site is dedicated to EPUD’s indus­trial services. These are pressed against the east side of the offices and pushed away to the northeast. The utility buildings are screened from direct sight of the offices and the entry sequence. Strategic plantings between the two halves of the site and between the offices and the parking areas reinforce the visual separation.

Structure

A slab-on-grade foundation was used for simplicity. Load – bearing concrete block walls were constructed on the slab running from north to south at 24 ft (7.3 m) intervals. This frame leaves the north and south solar orientations open for light and sun. A precast double beam with a U – shaped profile forms a lintel at the top of the block walls. Hollow-core concrete slabs were used across the 24 ft span to complete the building structure. To integrate airflow for thermal performance, the end cores of the concrete slabs were left open to the crossing channel of the U-beam.

Envelope

Sections of the building show how the north-south profile was configured to admit direct south light and to provide

a high clerestory window for illumination deep into the interior. This scheme is used on both wings as well as the connecting meeting hall. Several moderating elements are added to this profile to control solar heat gain and direct glare. On the interior, for both north and south windows, a deep light shelf blocks the view of the sky and reflects light off the ceiling and into the interior. This strategy is supplemented on the south elevation by an open trellis outside the lightshelf and a matching trellis at the ceiling line. Yet another trellis protects the south-facing cleresto­ry. In a subtle integration with site landscaping, these trel­lises are covered with Virginia creeper vines that shade the windows during the warm summer season. Because Virginia creeper is deciduous, it loses its leaves in time to allow the low angles of winter sun into the building. Characteristically, the vine bears small black berries in the winter and chartreuse, translucent young leaves in spring. By summer it has large dark green leaves, which turn red and translucent again by October.

The north and south wall openings are in-filled with 4 in. (102 mm) concrete block and backed up on the inte­rior with metal stud walls, R-19 insulation, and gypsum board. With a 1 in. air space between the concrete block and the insulation, this assembly yields a corrected thermal resistance of R-11.9. North and south glazing, as well as the clerestory window, uses the same aluminum framed, double-glazed glass units with a % in. air space between the glazings. The insulation value of the glass is R-1.4. To bal­ance light distribution, more high windows were used above the lightshelf than view windows beneath them. This gives each bay an H-shaped window divided by the trellis and light shelf. The entire assembly was pushed up so that the window head is at the ceiling line and daylight is given the greatest opportunity to infiltrate the space.

Above the hollow-core roof slabs, R-40 batt insulation is loose laid between steel channels and covered with a seamed metal roof. Correcting for thermal bridging, the conductance of the steel channels gives an R-35 thermal resistance for the roof. The east and west exterior walls are finished to match the north and south infill walls.

Mechanical

An air-cooled direct expansion air conditioner sits in a courtyard between the north juncture of the office and the warehouse. It serves a VAV fan distribution system pack­aged in the mechanical room adjacent to it in the north­east corner of the building. This system serves most of the EPUD offices, with conventional cooling delivered to fan distribution boxes in each zone. The large fan associated with the main air handler in the mechanical room oper­ates at a variable volume to match the total requirements of all the zone boxes.

The VAV fan is also used to provide night-flush venti­lation during cool summer night hours. Rather than recir­culating a mix of return air and outside air as it normally does, the fan switches to 100 percent outside air and deliv­ers it through the same ducts it uses during the day. Three additional makeup air fans blow filtered outside air into the second floor, ground floor, and engineering wing. Three exhaust fans then remove air from the building by extracting it through the hollow-core concrete floor and ceiling slabs. By morning the mass of the building is charged with “coolth,” or more technically, discharged of its heat accumulation from the previous day. Because the temperature of surrounding surfaces is so important to thermal comfort, this operation accomplishes a great deal of the next day’s cooling requirements in advance. Another cooling strategy is used on the hottest afternoons:

Figure 11.24

Distribution of July tem­peratures in Eugene for day and night hours.

Return air is switched-over from conventional ducts to the hollow slab cores. This harvests the previous night’s cool­ing that remains in its heavy mass and precools the room air before it is conditioned by the VAV system.

In winter, the core slabs are allowed to warm as heat from lights, sun, and activity in the building naturally stratify to ceiling height. Before the staff arrives on a cool morning, return air is taken through the warm slabs rather than through its conventional ductwork. This harvests heat stored from the previous day. In either the heating or the cooling mode, for return air or exhaust, the mass of the slabs is used to store heat when it is generated and give it up during cooler parts of the day. Having hollow-core air channels makes integrating the structure with the mechanical system direct and practical. Remember that the supporting concrete lintels were precast as U-shaped beams for just this purpose—picture them as manifolds feeding into and from the slab cores.

There is no central heating system in the building. Studies showed that it would be more efficient to forgo a heating plant or some form of perimeter zone reheat of the VAV system. Instead, spot heating is provided at each desk by a personally controlled electric resistance unit. By making the passive heating aspect of the building so important, the need for a central heating plant was elimi­nated completely.

Two special rooms had to have independent HVAC sys­tems. The computer room operated 24 hours per day and could not be set back to less comfortable levels at night with the rest of the building. It is served by a 2 ton heat pump in the northwest corner of the second floor. For the same rea­son, the 24-hour dispatch room in the northeast corner of the engineering wing has a 1.5 ton heat pump. Finally, an electrical submetering system was installed to monitor monthly energy use in various parts of the building.

Interior

Interior spaces are defined by the 24 ft structural bays plus the north, south, and clerestory daylight apertures. The central long axis of the typical plan is left open for circula­tion, access, and the routing of services. Most conspicuous is the long VAV distribution duct containing separate com­partments for the supply air and return air streams. On the second floor of the customer services wing this duct acts as another light shelf to scatter sky light from the clerestory.

The concrete structure is left exposed to the interior, providing a durable surface and the thermal benefits of internal mass. With so many hard surfaces in the room however, acoustical absorption had to be provided some­where or the space would be excessively noisy. This prob­lem was resolved by hanging acoustically absorptive baffles vertically from the ceiling, perpendicular to the windows in each bay. The baffles not only quiet the space, they also help to diffuse light and cut off direct view of the bright sky.

Daylighting design kept all the workstations within 20 ft of a window—at a ratio of less than 2.5 times the height of the window head. Bilateral lighting makes this low ratio possible in the first place, and the central clerestory pro­vides fill light throughout the spaces below. Balancing the distribution of light in the space was also accomplished by the proportion of windows above and below the light shelves so that it is not unduly bright beside the windows and dark in the middle of the room. Overall, the glass area amounts to about 20 percent of the floor area.

A postoccupancy evaluation was performed by archi­tecture students from the University of Oregon in the win­ter of 1999 under the direction of Alison Kwok. Using a set of portable data loggers, they measured temperature, humidity, and light levels in the building. They also sur­veyed staff members to gather impressions about the com­fort levels and how they operated their workstations in response to sun and light.

It was gratifying that the detailed study turned up few problems and several satisfactory results. Occupants were generally pleased with thermal and lighting conditions, glare was not perceived to be a problem, and only one group of occupants thought their space was too cold. Objectively, measured daylighting and thermal perform­ance matched design expectations, but the lighting con­trols needed fine-tuning.

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