On-Site Renewable Energy and Green Buildings: A System-Level

Subscriber access provided by UOW Library

Policy Analysis

On-site Renewable Energy and Green Buildings: A System-Level Analysis Sami G. Al-Ghamdi, and Melissa M. Bilec Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.5b05382 • Publication Date (Web): 31 Mar 2016 Downloaded from http://pubs.acs.org on April 14, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 26

Environmental Science & Technology

1

On-Site Renewable Energy and Green Buildings:

2

A System-Level Analysis

3

Sami G. Al-Ghamdi and Melissa M. Bilec*

4

Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA

5

*Corresponding author:

6

Tel.: +1 (412) 648-8075; Fax: +1 (412) 624-0135. E-mail address: [email protected]

7

Keywords: Green Building Rating Systems (GBRS); Leadership in Energy & Environmental

8

Design (LEED); Life Cycle Assessment (LCA); Building Information Modeling (BIM);

9

Commercial Buildings; Operational Environmental Impact in Buildings; On-Site Renewables

1 ACS Paragon Plus Environment


10

ABSTRACT

11

Adopting a green building rating system (GBRSs) that strongly considers use of renewable

12

energy can have important environmental consequences, particularly in developing countries. In

13

this paper, we studied on-site renewable energy and GBRSs at the system level to explore

14

potential benefits and challenges. While we have focused on GBRSs, the findings can offer

15

additional insight for renewable incentives across sectors. An energy model was built for 25 sites

16

to compute the potential solar and wind power production on-site and available within the

17

building footprint and regional climate. A life-cycle approach and cost analysis were then

18

completed to analyze the environmental and economic impacts. Environmental impacts of

19

renewable energy varied dramatically between sites, in some cases, the environmental benefits

20

were limited despite the significant economic burden of those renewable systems on-site and

21

vice versa. Our recommendation for GBRSs, and broader policies and regulations, is to require

22

buildings with higher environmental impacts to achieve higher levels of energy performance and

23

on-site renewable energy utilization, instead of fixed percentages.


Page 2 of 26

Page 3 of 26


24

INTRODUCTION AND BACKGROUND

25

The International Energy Agency (IEA) predicts high growth in renewable energy utilization

26

in all sectors, with the highest increases in the building sector. Specifically, by 2035, it is

27

expected that buildings will consume about 34% of final energy consumption from renewable

28

sources (excluding traditional biomass), compared to the 23% predicted in the industrial sector

29

and 15% in the transportation sector.1 Furthermore, in the next couple of years, renewables are

30

expected to surpass natural gas as the second-largest source of power generation and to approach

31

coal as the leading source by 2035.2 Many laws, national targets, and codes have been developed

32

and implemented around the world, focused on renewable energy. In 2015, 164 countries have

33

adopted at least one type of renewable energy target.3

34

Buildings are recognized as a technological sector where large improvements in sustainability-

35

related categories are achievable, including advances in renewable technologies. As such, in the

36

building design and construction industry, there are many programs and initiatives that

37

incorporate renewable energy use to support sustainable development goals and in line with the

38

previous predictable international trends.4-11 Today, Green Building Rating Systems (GBRSs)

39

represent an important part in the transformation of building design and construction, including

40

renewable installations. In this paper, we study on-site renewable energy and GBRSs at the

41

system level to explore potential benefits and challenges. While we have focused on GBRSs, the

42

findings can offer broader consequences related to any type of renewable building incentives

43

under consideration by policy makers. Adopting a green building rating system or any policy that

44

strongly considers use of renewable energy can offer important environmental and economic

45

considerations, particularly in developing countries.



46

Green Building Rating Systems (GBRSs)

47

Green Building Rating systems are often voluntary and intended to promote more sustainable

48

building design, construction and operation. They stimulate incorporation of environmental

49

concerns with economic benefits and other traditional decision criteria. Most GBRSs have

50

different subsets that cater to specific building projects such as retrofits, new construction,

51

commercial, residential, schools and healthcare facilities. Many countries develop their own

52

rating system based on local and regional factors like the type of building stock, climate, and

53

others. The individual circumstances of each country and region lead to the difficulty of creating

54

a single global green building ratings systems.12 Prominent rating systems include the Building

55

Research Establishment Environmental Assessment Methodology (BREEAM) developed in the

56

United Kingdom,4 Green Star from Australia,8 the German Sustainable Building Council System

57

(DGNB) from Germany,6 Estidama in the United Arab Emirates,7 the Comprehensive

58

Assessment System for Built Environment Efficiency (CASBEE) from Japan,10 and Leadership

59

in Energy and Environmental Design (LEED) developed in the United States.13 LEED is the

60

most internationally recognized initiative that provides a comprehensive third-party verification

61

system for green buildings. Today, more than 10 billion square feet of building space have been

62

certified by LEED in more than 135 countries, making it the most commonly used rating

63

system.14

64

LEED was developed by the U.S. Green Building Council (USGBC), evolving through several

65

versions over the past twenty years, with the official launch of the pilot version, LEED v1.0, in

66

1998. This version targeted only new construction and new commercial office buildings. LEED

67

then evolved continuously from the pilot version to LEED v2.0 in 2001; LEED v2.1 in 2003;

68

LEED v2.2 in 2005; LEED 2009 in 2009 and finally LEED v4.0 in 2013. At present, LEED has


Page 4 of 26

Page 5 of 26


69

expanded to have a more comprehensive structure, with a global alternative compliance path that

70

includes many subsystems.11

71

Renewable Energy and Green Building Rating Systems

72

Most GBRSs include renewable energy; renewable energy requirements are often optional and

73

take the form of credits/points that, when a requirement is met, contribute to a higher level of

74

certification (i.e., silver, gold, platinum). Some GBRSs, like BREEAM, use renewable

75

technologies as an option to reduce emissions, allowing the building to earn points when CO2

76

emissions are reduced by 10% to 30%.4 Other systems, such as CASBEE, offer more detail on

77

renewable technologies use, with rules about which types of renewable energy can be used and

78

how much energy needs to be produced on site.10

79

In LEED, renewable energy has been a part of the system from the beginning, where LEED

80

has offered credits for renewable on-site generation and contracts with green power providers.

81

LEED’s intent was to encourage and recognize increasing levels of self-supply of energy through

82

renewable technologies to reduce the environmental impacts associated with fossil fuel energy

83

use. The requirements and number of points allocated to the renewable energy credit (Energy

84

and Atmosphere, credit number 5) have changed from one version to the next, while the amount

85

of green power required (Energy and Atmosphere, credit number 7) has to a large extent

86

remained unchanged. However, in previous versions the duration of the green power contract

87

was for two years, whereas in the current version, LEED v4.0, the duration has been extended to

88

five years. Finally, LEED has added a pilot credit with a strategic dimension that supports future

89

use of renewable energy: the pilot credit requires the building structure to be capable of

90

supporting future renewable energy technologies and installation, such as planned photovoltaic

91

technologies for a roof.11 This work examined on-site renewable energy for two reasons. First, 5 ACS Paragon Plus Environment


92

the IEA predictions are geared towards on-site renewable energy, and second, designers and

93

decision-makers often want to make decisions related to their building project that can have a

94

direct and visible impact (i.e., solar panels on the building).

95

Some researchers argue that using a systems-level approach to fully understand environmental

96

impacts, such as life cycle assessment (LCA), may lead to higher performing buildings.15, 16 In

97

2009 LEED implicitly and explicitly integrated life cycle assessment (LCA) by rearranging

98

priorities, where for instance, energy consumption was given more consideration as opposed to

99

water or indoor environmental quality. This rearrangement in priorities was based on a new

100

weighting scheme, where building impacts are described in terms of 13 impact categories as

101

defined in TRACI (Tool for the Reduction and Assessment of Chemical and other environmental

102

Impacts) developed by the EPA (US Environmental Protection Agency). The weighting scheme

103

compares the impact categories to each other according to BEES (Building for Environmental

104

and Economic Sustainability), a tool developed by NIST (National Institute of Standards and

105

Technology).17-19 Over the years we can see changes in the requirements and points allocated to

106

each credit due to many factors; for example, the energy-referenced standard was updated,

107

reducing energy consumption at a code level as opposed to an aspirational level. The USGBC

108

strategy for LEED was to exceed the energy code via a prerequisite of fixed percentage of saving

109

from the energy model baseline: 0% in v2.0, 10% in v 2009 and 5% in v4.0.11, 20-23 Buildings can

110

achieve points when they go beyond the prerequisite.

111

Goal and Motivation

112

This research investigated the environmental and economic impacts of renewable energy (i.e.,

113

solar via photovoltaics and wind via turbines) produced on-site for high performance buildings to

114

understand their potential building and systems-level impacts. This research was done to better 6 ACS Paragon Plus Environment

Page 6 of 26

Page 7 of 26


115

understand the potential of on-site renewables in the Leadership in Energy and Environmental

116

Design (LEED) v4.0 rating system on a system-level scale. Specifically, in the most recent

117

LEED, v4.0, a building that produces 1% of its energy requirements receives 1 point; 5%, 2

118

points; and 10%, 3 points while in the previous version of LEED (version 2009), the on-site

119

renewable points available ranged from 1 to 7. However, at the same time, the IEA is assuming

120

an increase in renewable energy use in buildings. There is an apparent disconnect. Our aim is to

121

elucidate the potential of renewable energy in buildings and associated environmental impacts to

122

discern if LEED requirements are at a lower target than a building’s potential.

123

In our previous work, differences were observed in the environmental impacts among sites due

124

to differences in energy sources for the same model building.24 We suggested that consideration

125

of the energy sources for buildings should be reflected in LEED revisions, with a particular

126

suggestion of targeted goals versus aggregated certifications. This paper extends our previous

127

life-cycle thinking to examine the relationship between renewable energy potential, green

128

building rating systems, and life cycle environmental impacts. We evaluate how much energy the

129

buildings will actually produce and what would happen if green building rating systems like

130

LEED required that the energy produced on-site be increased in proportion to what already exists

131

for that building (not an outside fixed percentage) and in response to each building’s

132

environmental impact. In other words, it evaluates the value of having buildings be credited

133

based on the renewable energy percentage of what is available on-site and can be produced with

134

reasonable economic conditions.



135

METHODOLOGY AND PROCEDURE

136

We utilized the reference building that was modeled in our previous work using Building

137

Information Modeling (BIM).24 We also used the 25 energy models that we developed

138

independently for 25 sites, each of which represents different climatic, economic, natural

139

circumstances. Using Autodesk’s Green Building Studio (GBS), each energy model was

140

advanced to compute the renewable energy (solar and wind) produced on-site and available

141

within the building footprint and regional climate. A life-cycle approach and cost analysis were

142

used to analyze the environmental and economic impacts while considering the different energy

143

sources and associated prices at each site.

144

Reference Building and Energy Models

145

The case study building is a 43,000 ft2 (4000 m2) office building that was designed to be close

146

to the LEED median building of 40,000 ft2 (3,716 m2). The building consists of 4 floors to be

147

used for general office space, professional offices, or administrative offices. Operational

148

schedules were set to be the same according to the local time and calendar of each location,

149

taking into account holidays and daylight savings time. All of the building materials that shape

150

the thermal characteristics and other variables in each location (independent from the other sites)

151

comply with the appropriate codes, as will be clarified subsequently. All construction materials

152

meet the minimum R-value requirements ASHRAE 90.1 for each location.25 Table 1 illustrates

153

samples of the changes in the thermal properties and construction materials to suit the climatic

154

variations based on the requirements of ASHRAE. Table 1 shows two selected buildings: one

155

from Finland, where the climate is cold and moist, the other from Brazil, where the climate is

156

very hot and humid; it also shows the changes in proportion of northern and southern windows

157

based on the building’s location, i.e., if it is in the northern or southern hemisphere. 8 ACS Paragon Plus Environment

Page 8 of 26

Page 9 of 26


158

The 25 reference building models are hypothetical models with ideal operations that meet the

159

aforementioned requirements. We utilized GBS, a BIM compatible energy analysis tool that

160

meets the requirements of LEED for calculating a building’s baseline performance according to

161

ANSI/ASHRAE/IESNA Standard 90.1 (Appendix G).25 We then used ASHRAE baseline HVAC

162

system types that matched building type and size. Other characteristics and variables were

163

identified as follows: HVAC efficiency and lighting power density were set to meet ASHRAE

164

90.1;25 equipment power density was set to meet the California 2005 Title 24 Energy Code;26 and

165

occupancy density and ventilation were set to meet ASHRAE 62.1.27 Any other characteristics

166

were set by default through GBS to follow the 2003 CBECS (Commercial Buildings Energy

167

Consumption Survey).28

168

Table 1. Detailed description of the thermal properties and construction materials in two selected buildings

Building Components Category Roofs

Exterior Walls

Interior Walls Interior Floors

Raised Floors

Slabs On Grade

Fixed Windows

ASHRAE climate zone: 6A (Cold, Humid) Vantaa, Southern Finland, Finland Thermal properties Construction Layers

ASHRAE climate zone: 1A (Very Hot, Humid) Barreiras, Bahia, Brazil Thermal properties Construction Layers

R20 over Roof Deck U-Value: 0.04

1. Blt-Up Roof 3/8in 2. Bldg Paper Felt 3. MinBd 3in R-10.4 4. MinBd 3in R-10.4 5. Wood Sft 3/4in R13 Wood Frame Wall 1. Wood Shingle U-Value: 0.08 2. Bldg Paper Felt 3. Wood Sft 3/4in 4. MinWool Batt R13 w/(2x4) Frame 16in oc 5. GypBd 5/8in Uninsulated Wall 1. GypBd 5/8in U-Value: 0.41 2. Air Space 3. GypBd 5/8in R0 Wood Frame 1. Wood Sft 3/4in Carpeted Floor 2. MinWool Batt R0 U-Value: 0.20 w/2x4 Frame 16in oc 3. Carpet & Fiber Pad Uninsulated concrete 1. Soil contact for slab uninsulated slab U-Value: 0.03 2. Soil 8in 3. Conc HW 140lb 8in 4. Carpet & Fiber Pad Uninsulated concrete 1. Soil contact for slab uninsulated slab U-Value: 0.03 2. Soil 8in 3. Conc HW 140lb 8in 4. Carpet & Fiber Pad 2,970 ft² North Facing Windows: Double Clear U-SI 3.16, U-IP 0.56, SHGC 0.69, VLT 0.78 (27 windows) U-Value:3.16 W/(m²-K), SHGC:0.69, Vlt:0.78 9,452 ft² Non-North Facing Windows: Double Clear U-SI 3.16, U-IP 0.56, SHGC 0.69, VLT 0.78 (88

R15 over Roof Deck U-Value: 0.06

R13 Wood Frame Wall U-Value: 0.08

R0 Metal Frame Wall U-Value: 0.41 Interior 4in Slab Floor U-Value: 0.74

U 0.322 Mass Floor U-Value: 0.24

Uninsulated concrete slab U-Value: 0.03

1. Blt-Up Roof 3/8in 2. Bldg Paper Felt 3. MinBd 2in R-7 4. MinBd 2in R-7 5. Wood Sft 3/4in 1. Wood Shingle 2. Bldg Paper Felt 3. Wood Sft 3/4in 4. MinWool Batt R13 w/(2x4) Frame 16in oc 5. GypBd 5/8in 1. GypBd 5/8in 2. Air Space 3. GypBd 5/8in 1. Conc HW 140lb 4in

13,394 ft² (1,244 m²)

1. Conc HW 140lb 10in 2. Carpet & Fiber Pa

570 ft² (53 m²)

1. Soil contact for uninsulated slab 2. Soil 8in 3. Conc HW 140lb 8in 4. Carpet & Fiber Pad 2,736 ft² South Facing Windows: Double Clear U-SI 3.16, U-IP 0.56, SHGC 0.69, VLT 0.78 (28 windows) U-Value:3.16 W/(m²-K), SHGC:0.69, Vlt:0.78 9,686 ft² Non-South Facing Windows: Double Clear U-SI 3.16, U-IP 0.56, SHGC 0.69, VLT 0.78 (87


Total Modeled Area

31,952ft² (2,968 m²)

34,903 ft² (3,243 m²) 29,796 ft² (2,769 m²)

12,824 ft² (1,191 m²)

12,422 ft² (1,154 m²)


Fixed Skylights

windows) U-Value:3.16 W/(m²-K), SHGC: 0.69, Vlt:0.78 720 ft² Non-North Facing Windows: Double Clear USI 3.16, U-IP 0.56, SHGC 0.69, VLT 0.78 (80 skylights) U-Value:3.16 W/(m²-K), SHGC: 0.69, Vlt:0.78

windows) U-Value: 3.16 W/(m²-K), SHGC: 0.69, Vlt:0.78 324 ft² South Facing Windows: Double Clear U-SI 3.16, U-IP 0.56, SHGC 0.69, VLT 0.78 (36 skylights) U-Value:3.16 W/(m²-K), SHGC:0.69, Vlt:0.78

Page 10 of 26

720 ft² (67 m²)

396 ft² Non-South Facing Windows: Double Clear USI 3.16, U-IP 0.56, SHGC 0.69, VLT 0.78 (44 skylights) U-Value:3.16 W/(m²-K), SHGC:0.69, Vlt:0.78

169

Renewable Energy Modeling

170

Today, there are a variety of options and technologies available for on-site renewable energy

171

systems. Those systems are either for electricity generation or thermal systems, with energy

172

coming from solar, wind, geothermal or biomass systems. In this study, we focus on two types of

173

renewable energy: solar and wind for electricity generation only. This decision was made due to

174

the limited data available for modeling and to reduce the number of assumptions. Using

175

Autodesk’s Green Building Studio (GBS) and the 25 energy models built previously, the on-site

176

renewable energy sources for each location were modeled and calculated. All data for each site

177

were collected from the nearby weather stations about 1.8 mi (2.9 km) and 3.6 mi (5.8 km) from

178

the building. Figure 1 illustrates 6 selected locations out of the 25 in the study sample. The data

179

comprise: annual solar radiation and annual wind speed. The solar radiation is represented in

180

column charts while the wind is represented in wind roses that show wind speed and gusts

181

direction per time percentage. All 25 sites data are shown in (SI-B).

182

Solar Power On-Site. Solar energy is the most abundant of all energy resources and has many

183

applications. Currently, the maturity of the various solar technologies available differs, and their

184

adoption and applicability depends on local conditions and government policies.29 Solar energy

185

conversion comprises an enormous group of different technologies designed to satisfy a diversity

186

of energy service needs. Photovoltaic (PV) cells, or solar cells, are commonly used in building

187

applications compared to other technologies like concentrating solar power (CSP). About 85-

188

90% of the PV market is dominated by wafer-based crystalline silicon (c-Si) cell technologies 10 ACS Paragon Plus Environment

Page 11 of 26


189

that include mono- or single-crystalline silicon (sc-Si) and multi-crystalline silicon (mc-Si).

190

Other considerable solar technologies, like thin films, represent 10-15% of the market share.

191

Less than 1% of the market is comprised of technologies like organic solar cells and

192

concentrating PV technologies.30 In this study we used sc-Si with a conversion efficiency of

193

13.8% where the current efficiencies in commercial modules are about 14-20% for sc-Si and 13-

194

15% for mc-Si.30 In the case study buildings, all possible surfaces were utilized, including both

195

roof systems that cover all roofs and façade systems that cover exterior walls and fixed windows

196

through building integrated photovoltaics (BIPV). After the solar modeling of all possible

197

surfaces was done, we then considered only the surfaces that met economic settings; the

198

maximum payback period for each surface was set to not exceed the building life span (50

199

years).

200

We selected the economic payback period to be 50-years, even though this length of time is

201

considerably longer than typically acceptable payback periods. We included this economic

202

aspect as it does play a pivotal role in the deployment of renewable energy; however, the central

203

part of this work is the environmental analysis. In today's market, most solar panels come with a

204

warranty between 25 or 30 years. For electricity retail prices for U.S. locations, we used U.S.

205

DOE Energy Information Administration data; for international locations outside of the U.S., we

206

used each country’s average retail price from IEA. Our payback figures did not consider any

207

federal and state energy incentives, tax breaks, loan solutions or system derating factors.

208

Within the last three decades, substantial cost reductions have been seen in solar technologies,

209

with PV prices falling sharply from about $22 per watt in 1980 to less than $1.5 per watt in 2010.

210

Installed prices vary according to country; for example, today’s prices in the United States are

211

higher than those in most other major national PV markets.31 These pricing disparities can be



Page 12 of 26

212

partially attributed to differences in soft costs, with soft costs in this case including, for example,

213

system design, permitting, and inspection. According to National Renewable Energy

214

Laboratory’s annual survey, the soft costs accounted for a significant portion of the total installed

215

PV system in the United States; approximately 64% of the total residential system price and 52%

216

of the commercial system price.32 In this study, we chose a conservative panel cost of $8.00 per

217

watt ($102.62 per ft²), based on a study by the Department of Energy's Lawrence Berkeley

218

National Laboratory that examined 37,000 grid-connected PV systems in the United States.33

219

The panel cost includes materials and labor to install a complete grid-connected solar electric

220

system.

221

Wind Power On-Site. In many applications today, wind power is seen as a mature renewable

222

energy source, whether it is on- or offshore especially in large size applications. Small wind

223

applications that are grid-connected or isolated are also employed for both residential and

224

commercial electricity needs. Many economic and social development benefits can be provided

225

by these different applications. When used in building applications, there are many common

226

challenges. Perhaps the largest is that wind resources are highly site-specific and can be difficult

227

to implement in urban settings. Also, smaller scale wind turbines cost less overall, but are more

228

expensive in terms of cost for each kilowatt of energy produced.34 In this study, we employ wind

229

power in a simplified way and mainly for the purpose of comparison with solar power. We

230

assumed five on-site wind turbines (15 ft in diameter, suitable for our office building), with cut-

231

in and cut-out winds of 6 mph and 45 mph respectively. The wind turbines were located at the

232

coordinates of the weather data shown in Figure 1. The turbines were placed on a horizontal axis

233

with rated power of 4,020 watt at 25 mph.


Page 13 of 26

234 235 236 237 238 239 240 241 242 243


Figure 1. Solar and wind modeling information at 6 selected locations out of the 25 in the study sample. The data were collected from the closest weather station to each building site, the distance ranging between 1.8 mi (2.9 km) and 3.6 mi (5.8 km). The column charts represent the sum of the annual solar radiation in (kWh/m2). The solar radiation data include: Global Horizontal Radiation (GHR), Direct Normal Irradiance (DNI) and Diffuse Horizontal Irradiance (DHI). GHR here is the sum of the DNI and DHI multiplied by the cosine of the angle between the direction of the sun and the zenith (directly overhead). No ground-reflected radiation was considered. The radar chart (wind rose) represents the wind data on-site including: wind speed, direction and frequency. The radial scale is the percentage of the time per year, and it is not the same across the different locations. All 25 sites data are shown in (SI-B).

244

Life Cycle Assessment (LCA)

245

Life Cycle Assessment (LCA) was used to analyze the life cycle environmental impacts

246

resulting from each building in the 25 different locations. The boundaries of the study (as shown

247

in the Figure 2) focused on two components. First, it examined the life cycle environmental

248

impacts of each building’s electricity consumption, including the full life cycle of power

249

generation from raw materials to power production, but excluding transmission. Second, it

250

looked at the life cycle environmental impacts of the on-site solar and wind systems; power 13 ACS Paragon Plus Environment


Page 14 of 26

251

transmission was excluded from the study due to high dissimilarity between sites and

252

infrastructure, particularly in developing countries. The average electric power transmission and

253

distribution losses in the United States is about 6% of total output. This percentage varies widely

254

between and within different countries from less than 5% in countries such as Germany, Finland

255

and Japan, and more than 20% in countries such as Venezuela, Moldova, and Albania.35

256

Variation also occurs within a single country; for example, the average transmission and

257

distribution losses in the United States per regional grid is about 9.5% in US Eastern, 8.4% in US

258

Western and 16.1% in Texas.36 Due to these variation and the number of sites in our study, we

259

did not include transmission and distribution losses.

260 261 262 263 264

Figure 2. The boundaries of the study within the built environment for each location. Data were collected for the five US sites from the US Environmental Protection Agency, EGRID 2006 Data and 2004 Plant Level Data.37 The data for the other 20 sites were obtained from the 2009 Carbon Monitoring for Action (CARMA) database 39

International Energy Agency (IEA) database. The data are presented in detail in (SI-A).


38

and

Page 15 of 26

265


The four steps in LCA were followed.40,

41

The first step, Goal and Scope, involved

266

considering the entire life cycle of the energy used in the building. For this step, the functional

267

unit was the building annual electricity consumption. To complete the second step, Life Cycle

268

Inventory (LCI), data were drawn from US Life Cycle Inventory-based databases (USLCI);36

269

Ecoinvent;42 then other databases, respectively.43,

270

were collected for the US sites from the US Environmental Protection Agency, EGRID 2006

271

Data and 2004 Plant Level Data.37 For the international sites, data were obtained from the 2009

272

Carbon Monitoring for Action (CARMA) database

273

database.39 To complete the third step, Life Cycle Impact Assessment (LCIA), the inputs and

274

outputs of each process in the power generation were calculated using the Tool for the Reduction

275

and Assessment of Chemical and other environmental Impacts (TRACI) 2 V3.01. The fourth

276

step, Interpretation, where the significant findings or conclusions are discussed based on the

277

results of the LCIA, is discussed in the subsequent section in detail.

44

For the electric power plant source, data

38

and International Energy Agency (IEA)

278

RESULTS AND DISCUSSION

279

Our central question “How much energy will the buildings actually produce and what would

280

happen if green building rating systems like LEED demand that the energy produced on-site be a

281

proportion of what already exists (not a fixed percentage) and in response to each building’s

282

environmental impact?” was first broadly considered. The results from our sample size and

283

models elucidated key variations between sites, variation which was expected due to the variety

284

of energy sources (electricity grid mix), natural resources (i.e. solar radiation and wind speed)

285

and economic conditions (domestic energy prices) present for each. In the photovoltaic analysis,

286

around 20 of the 25 buildings were physically capable (i.e., based on building size, geometry and 15 ACS Paragon Plus Environment


Page 16 of 26

287

solar potential) of producing 20% to 40% of the buildings’ electricity requirements, leading to

288

economic savings of $20,000 to $100,000 (see Figure 3) and greenhouse gas emission reductions

289

of 635,000 to 1,347,000 kg CO2 equiv per building per year (see Figure 4). In the wind analysis,

290

2 buildings were able to produce 5% and 9% of their electric requirements with economic

291

savings ranging from $6,000 to $11,000, respectively. Eight other buildings were able to produce

292

only 1% or less of their electric requirements using wind power. The overall wind contribution in

293

the mitigation of equivalent CO2 emissions ranged from 8,500 to 86,000 kg. The next sections

294

summarize the main features garnered from the results regarding energy and economic

295

performance and overall environmental impacts (see Figure 3 and Figure 4).

296

Energy and Economic Performance

297

While the size and function of the building were identical in all of the locations, the

298

consumption of electricity varied based on the different climatic conditions in each context.24

299

These variations existed even though the building interacted with the climate by increasing

300

thermal insulation levels according to the energy code (ASHRAE 90.1), as described in Table 1.

301

The electricity consumption, as shown in Figure 3, ranged from 500 to 800 MWh/year while the

302

economic burden of this consumption varied significantly from $11,500 to $207,000 per year

303

depending on the local economic circumstances at each location. The total system payback

304

period for the 25 locations ranged from 19 to 48 years based on the potential renewable energy

305

availability on-site and the prices of domestic electricity.

306

The photovoltaic results also varied from one location to another, both in the amount of

307

electricity produced and in the area of roofs and walls covered by photovoltaic panels. Utility

308

rates often vary significantly by time of day and by season and are typically highest during

309

afternoon hours in the summer, when PV production is highest. However, because our 16 ACS Paragon Plus Environment

Page 17 of 26


310

calculations did not take into account daily or seasonably higher rates, but instead used a flat

311

rate, the calculated payback period is conservative (longer) than the actual payback period is

312

likely to be. Applied electric costs (utility rates) were based on average domestic prices, with the

313

assumption that energy prices would increase by 2% per year.

314 315 316 317 318 319 320

production on-site, referenced on the left in (MWh). The lines with red markers represent the annual electricity cost

321

The local economic circumstances play a major role in the development of renewable energy.

322

In the results for the 25 locations, as shown in Figure 3, domestic energy prices dominated the

323

results of the renewable energy sources on-site. The 25 locations can be classified into 3 groups

324

according to the economic performance. First, locations like Hawaii and Italy show good

Figure 3. Annual electricity requirements, renewable production, payback, and cost for the 25 locations included in the study. The columns represent the annual electricity requirements at each site and the renewable potential

and the annual savings at each site, referenced on the right in thousands of US dollars. The blue circles indicate the ASHRAE climate zone. The yellow triangles indicate the PV system payback period in years and is associated with the electricity production from PV (yellow columns).



Page 18 of 26

325

performance compared to the others, due to the moderate availability of renewable energy

326

sources and high prices of conventional power from the grid. In Hawaii and Italy the building

327

can produce about 45% and 55% of its electricity needs, respectively, from solar only; the

328

payback period for both locations was 24 years. The buildings in these locations also can

329

produce about 5% and 1% of its required electricity, respectively, from wind power. The annual

330

savings were about $105,000 in Hawaii and $96,000 in Italy. Second, some locations, like Chile,

331

showed an excellent performance due to the high availability of renewable energy sources and

332

moderate energy local prices. The building in Chile can produce about 74% of its required

333

electricity using solar power and 1% from wind power. However, despite the high percentage of

334

production on-site in Chile, the payback period was still around 31 years and annual savings only

335

around $59,000. Third, locations like Iowa, Finland, South Africa and Russia show poor

336

performance as those locations are unlikely to take advantage of renewable energy due to the

337

cheap prices of conventional power from the grid, regardless of the availability of renewable

338

energy on-site. The location in Iowa, USA, for example, was not able to produce electricity from

339

renewable energy sources despite the higher levels of solar radiation and wind speed due to

340

cheaper electricity prices compared to the locations with similar access to renewable energy

341

sources like Alberta, Canada.

342

Environmental Impacts

343

Environmental impacts depend on the primary sources of the energy of a particular place. In

344

buildings, the use phase and associated energy use represent the greatest environmental

345

impacts,45 approximately seventy to ninety percent.46 The environmental impacts of energy use

346

in buildings can be significantly reduced by the use of renewable energy sources.47 The

347

environmental impacts of the 25 buildings modeled become more complicated to understand as 18 ACS Paragon Plus Environment

Page 19 of 26


348

we analyzed environmental loads for buildings around the world, which rely on different energy

349

sources. As shown in Figure 4, essential discrepancies were observed in the results among sites,

350

with differences clearly increasing with more diversified energy sources. Range of variation in

351

emissions was from 2,244 and 2,465 kg CO2 equiv in Brazil and Japan, respectively, which have

352

dominant energy sources of hydro and nuclear, respectively, to 851,427 and 759,588 kg CO2

353

equiv in India and China, respectively, which both have coal as the dominant energy source.

354 355 356 357 358 359 360 361

Figure 4. Annual Life Cycle CO2 equivalent emissions in the 25 locations included in the study – use phase. The stacked columns represent the potential CO2 equivalent emissions at each site, referenced on the left in metric tons. The blue portion denotes the impact from the systems on-site comprising the entire system cradle-to-grave life cycle. The orange portion denotes the impact from the annual grid electricity consumption. On the negative side, the yellow portion denotes how the impacts can be mitigated using a PV system while purple shows how the impact can be mitigated using wind turbines. The lines with green markers represent the annual net CO2 equivalent emissions, referenced on the right in kg per kWh.



Page 20 of 26

362

The mitigated environmental impacts were limited despite the significant economic burden of

363

renewable systems in locations such as Brazil, Chile and France. The limitation here was due to

364

the prior utilization in these sites of electricity that was generated from non-fossil fuel resources,

365

hydroelectric power in the case of Brazil and Chile, nuclear power in the case of France. For

366

example, the building in Chile was capable of producing about 74% of its electricity

367

requirements, yet its environmental footprint was minor compared to others because its initial

368

energy source was hydroelectric. On the other hand, the buildings in China and India, have

369

smaller savings percentages in electricity (23% and 29%); however, the carbon emissions

370

mitigation amount was around 50 times greater compared to that in Chile, as China and India are

371

more dependent on fossil fuels. The highest environmental benefits (minimal emissions) were in

372

Ethiopia, Mauritania and Colombia. The results for these locations present an optimistic outlook

373

of what renewable energy on-site can do, in developing countries particularly.

374

Outlook for GBRSs and Renewable Energy

375

GBRSs can play a significant role in increasing the efficiency of buildings and therefore in

376

reducing their economic and environmental burdens. GRBSs in the U.S. often lead the market,

377

codes, and regulations. GBRSs can encourage the use of on-site renewable energy in buildings,

378

often by requiring a fixed percentage of renewable on-site utilization, and award points/credits

379

incrementally based on this percentage.4, 11 However, according to the results presented, some of

380

the buildings can produce more energy than others with the same economic circumstances (i.e.,

381

payback period of any given surface not exceeding the building life span of 50 years), and some

382

other buildings cannot produce any energy on-site at all with this constraint. For example, the

383

buildings in Hawaii, California, Turkey, Chile, Italy and Ethiopia can produce more than 50% of

384

their electricity needs from on-site renewables. However, the buildings in Iowa, Finland, 20 ACS Paragon Plus Environment

Page 21 of 26


385

Indonesia, South Africa and Russia were not able to produce any energy on-site either due to the

386

lack of renewable energy sources or/and some economic factors. Environmental impacts of

387

renewable energy vary dramatically from one site to another, making the benefits from the

388

environmental point of view irregular; in some cases, as mentioned in this paper, the

389

environmental benefits may be very limited despite the significant economic burden of those

390

renewable systems on-site and vice versa.

391

From a policy viewpoint, we can see that the existing requirement of a fixed percentage of

392

renewable energy use in today’s GBRSs has deficiencies; further, different renewable energy

393

technologies have considerable variations in their environment impacts. Moreover, the wind

394

power (turbines) in this study shows very limited benefits for the case study building compared

395

to solar (PVs). These results highlight the need for today’s GBRSs to be more sophisticated in

396

dealing with renewable energy by implementing more detailed requirements that can maximize

397

the benefits of various renewable energy technologies.

398

While we used GBRSs to illustrate the importance of aligning on-site renewable energy targets

399

and potential reductions in environmental impacts, the findings may be considered in a broader

400

sense in terms of regulations, national targets, and codes. Arbitrary percentage reductions should

401

be reconsidered, and strategic holistic analyses can potentially offer even greater environmental

402

benefits. A reflection on how to consider on-site renewable energy is particularly crucial at this

403

point in time, since GBRSs are currently evolving and undergoing international expansion, with

404

a particular focus on the idea of targeted goals versus nominal percentages.

405

Our recommendation for GBRSs, and broader policies and regulations, is to require buildings

406

with higher environmental impacts to achieve higher levels of energy performance and on-site

407

renewable energy utilization, instead of on the current fixed percentage of improvement. The



408

results of this study reveal that location-specific results, when paired with life cycle assessment,

409

can be an effective means to achieve a better understanding and reduction of the adverse

410

environmental impacts resulting from energy consumption.

411

ASSOCIATED CONTENT

412

Supporting Information: Full modeling, calculation and original data related to this article can

413

be found in the supplementary data file attached (SI-A and SI-B). This material is available free

414

of charge via the Internet at http://pubs.acs.org

415

AUTHOR INFORMATION

416

*Corresponding author: Tel.: +1 (412) 648-8075; Fax: +1 (412) 624-0135. E-mail address:

417

Page 22 of 26

[email protected]

418

Notes: The authors declare no competing financial interests.

419

ACKNOWLEDGMENTS

420

We would like to acknowledge the University of Pittsburgh’s Mascaro Center for Sustainable

421

Innovation for their support. This material is based upon work supported by the National Science

422

Foundation under EFRI-SEED (1038139). Any opinions, findings, and conclusions or

423

recommendations expressed in this material are those of the author(s) and do not necessarily

424

reflect the views of the National Science Foundation.


Page 23 of 26

425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468


REFERENCES 1. IEA, World energy outlook International Energy Agency (IEA), Organisation for Economic Co-operation Development (OECD): Paris, France, 2010. 2. IEA, World energy outlook International Energy Agency (IEA), Organisation for Economic Co-operation Development (OECD): Paris, France, 2013. 3. IRENA, Renewable Energy Target Setting. International Renewable Energy Agency (IRENA): Abu Dhabi, UAE, 2015. 4. BREEAM, BREEAM New Construction Technical Manual. BRE Global Limited: Herforshire, 2011; Vol. 1. 5. CBSC, California green building standards code: California code of regulations. International Code Council; California Building Standards Commission: Sacramento, CA, 2013. 6. DGNB, DGNB Certification System. In German Sustainable Building Association: Germany 2011. 7. Estidama, Pearl Building Rating System: Design and Cosutrction, Version 1.0. In Abu Dhabi Urban Planning Council: Abu Dhabi UAE, 2012; p 233. 8. GBCA, Green Star Rating Tool. In Green Building Council Australia Austrailia 2010. 9. GBI, Green Globes For New Construction - Technical Reference Manual - Version 1.3. Green Building Initiative Portland, OR, 2014. 10. IBEC, Comprehensive Assessment System for Built Environment Efficiency (CASBEE) CASBEE for New Construction - Technical Manual. Institute for Building Environment and Energy Conservation: Tokyo, Japan, 2010. 11. USGBC, LEED reference guide for building design and construction, LEED v4.0. U. S. Green Building Council: Washington, DC, 2013. 12. Reed, R.; Bilos, A.; Wilkinson, S.; Schulte, K.-W., International Comparison of Sustainable Rating Tools. The Journal of Sustainable Real Estate 2009, 1, (1), 1-20. 13. USGBC, LEED Existing Buildings Version 2.0 Reference Guide. 2006. 14. USGBC, About USGBC. http://www.usgbc.org/about (2/7/2014), 15. Scheuer, C.; Keoleian, G. A.; Reppe, P., Life cycle energy and environmental performance of a new university building: modeling challenges and design implications. Energy and Buildings Energy and Buildings 2003, 35, (10), 1049-1064. 16. Blengini, G. A.; Di Carlo, T., The changing role of life cycle phases, subsystems and materials in the LCA of low energy buildings. Energy & Buildings 2010, 42, (6), 869-880. 17. Bare, J.; Norris, G.; Pennington, D.; McKone, T., TRACI - The Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts. Journal of Industrial Ecology 2002, 6, (3/4), 49-78. 18. Gloria, T. P.; Lippiatt, B. C.; Cooper, J., Life Cycle Impact Assessment Weights to Support Environmentally Preferable Purchasing in the United States. Environmental Science & Technology 2007, 41, (21), 7551-7557. 19. USGBC, LEED 2009 Weightings Background; Washington, DC, 2008. 20. USGBC, LEED reference package, version 2.0. U.S. Green Building Council: Washington, D.C., 2001. 21. USGBC, LEED reference guide for new construction & major renovations (LEED-NC), version 2.1. U.S. Green Building Council: Washington, D.C., 2003. 23 ACS Paragon Plus Environment


469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514

22. USGBC, LEED-NC for new construction : reference guide, version 2.2. U.S. Green Building Council: Washington, DC, 2005. 23. USGBC, LEED Reference Guide for Green Building Design and Construction. U.S. Green Building Council: Washington, DC, 2009. 24. Al-Ghamdi, S. G.; Bilec, M. M., Life-Cycle Thinking and the LEED Rating System: Global Perspective on Building Energy Use and Environmental Impacts. Environmental Science & Technology 2015, 49, (7), 4048–4056. 25. ASHRAE; ANSI; IESNA, Standard 90.1-2007: Energy Standard For Buildings Except LowRise Residential Buildings. ASHRAE (American Society of Heating and Refrigerating and Air-Conditioning Engineers), ANSI (American National Standards Institute) and IESNA (Illuminating Engineering Society of North America): Atlanta, GA, 2007. 26. California Building Standards Commission, 2005 California Energy Code: California Code of Regulations, Title 24, Part 6. California Building Standards Commission: Sacramento, CA, 2005. 27. ASHRAE; ANSI; IESNA, Standard 62.1-2007: Ventilation for Acceptable Indoor Air Quality. ASHRAE (American Society of Heating and Refrigerating and Air-Conditioning Engineers), ANSI (American National Standards Institute) and IESNA (Illuminating Engineering Society of North America): Atlanta, GA, 2007. 28. US EIA, Commercial buildings energy consumption survey (CBECS). In US Energy Information Administration (EIA), Office of Integrated Analysis and Forecasting, U.S. Dept. of Energy: Washington, DC, 2003. 29. Arvizu, D.; Balaya, P.; Cabeza, L.; Hollands, T.; Jäger-Waldau, A.; Kondo, M.; Konseibo, C.; Meleshko, V.; Stein, W.; Tamaura, Y.; Xu, H.; Zilles, R., Direct Solar Energy. In Renewable energy sources and climate change mitigation: special report of the Intergovernmental Panel on Climate Change, Edenhofer, O.; Madruga, R. P.; Sokona, Y.; Seyboth, K.; Eickemeier, P.; Matschoss, P.; Hansen, G.; Kadner, S.; Schlömer, S.; Zwickel, T.; Stechow, C. V., Eds. Cambridge University Press: New York, NY, 2012. 30. IEA, Technology Roadmap: Solar Photovoltaic Energy. International Energy Agency (IEA), Renewable Energy Division. Organisation for Economic Co-operation Development (OECD): Paris, France, 2010. 31. Barbose, G.; Darghouth, N. Tracking the Sun VIII: The Installed Price of Residential and Non-Residential Photovoltaic Systems in the United States; Lawrence Berkeley National Laboratory (LBNL): Berkeley, CA, USA, 2015. 32. Zuboy, J.; National Renewable Energy Laboratory, G. C. O., Benchmarking Non-Hardware Balance-of-System (Soft) Costs for U.S. Photovoltaic Systems, Using a Bottom-Up Approach and Installer Survey - Second Edition. United States, 2013. 33. Wiser, R.; Galen, B.; Carla, P. Tracking the sun: the installed cost of photovoltaics in the U.S. from 1998-2007; Lawrence Berkeley National Laboratory (LBNL): Berkeley, CA, USA, 2009. 34. Sathaye, J.; Lucon, O.; Rahman, A.; Christensen, J.; Denton, F.; Fujino, J.; Heath, G.; Kadner, S.; Mirza, M.; Rudnick, H.; Schlaepfer, A.; Shmakin, A., Renewable Energy in the Context of Sustainable Development. In Renewable energy sources and climate change mitigation: special report of the Intergovernmental Panel on Climate Change, Edenhofer, O.; Madruga, R. P.; Sokona, Y.; Seyboth, K.; Eickemeier, P.; Matschoss, P.; Hansen, G.; Kadner, S.; Schlömer, S.; Zwickel, T.; Stechow, C. V., Eds. Cambridge University Press: New York, NY, 2012. 24 ACS Paragon Plus Environment

Page 24 of 26

Page 25 of 26

515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543


35. IEA, Statistics - International Energy Agency. In International Energy Agency (IEA), Organisation for Economic Co-operation Development (OECD): Paris, France, 2014. 36. NREL, US Life-Cycle Inventory Database (USLCI). In National Renewable Energy Laboratory (NREL),: Golden, CO, 2010. 37. US EPA, Plant Level Data. In eGRID 2012 V 1.0 - with year 2009 data May 2011 ed.; US Environmental Protection Agency Washington, DC, 2012. 38. CARMA, Power Plant Data. In Carbon Monitoring for Action (CARMA) V 3.0 - with year 2009 data 2009 ed.; Center For Global Development: Washington, DC, 2009. 39. IEA, Electricity Generation by Fuel. In IEA Statistics - with year 2009 data, 2009 ed.; International Energy Agency (IEA): Paris, France, 2009. 40. ISO, Environmental management - Life cycle assessment: Principles and framework. International Organization for Standardization (ISO): Switzerland, Geneva, 1997. 41. ISO, Environmental management - life cycle assessment: requirements and guidelines. International Organization for Standardization (ISO): Switzerland, Geneva, 2006. 42. Frischknecht, R.; Jungbluth, N.; Althaus, H.-J.; Doka, G.; Dones, R.; Heck, T.; Hellweg, S.; Hischier, R.; Nemecek, T.; Rebitzer, G.; Spielmann, M., The ecoinvent Database: Overview and Methodological Framework. The international journal of life cycle assessment. 2005, 10, (1), 3. 43. Franklin Associates Ltd., Franklin LCI US 98. In Franklin Associates Ltd 1998. 44. ESU Services Ltd., ETH-ESU LCI 96. In ESU Services Ltd., 1996. 45. Aktas, C.; Bilec, M., Impact of lifetime on US residential building LCA results. The International Journal of Life Cycle Assessment 2012, 17, (3), 337-349. 46. Ortiz, O.; Castells, F.; Sonnemann, G., Sustainability in the construction industry: A review of recent developments based on LCA. Constr Build Mater Construction and Building Materials 2009, 23, (1), 28-39. 47. Citherlet, S. D. T., Energy and environmental comparison of three variants of a family house during its whole life span. Building and Environment 2007, 42, (2), 591-598.



544

TOC/Abstract Art

545


Page 26 of 26

On-Site Renewable Energy and Green Buildings: A System-Level

Recommend Documents