EXHIBIT 99.1

WGL Holdings, Inc. Reports Fiscal Year 2011 Financial Results;

Issues Fiscal Year 2012 Guidance

Consolidated Results

WGL Holdings, Inc. (NYSE: WGL), the parent company of Washington Gas Light Company (Washington Gas) and other energy-related subsidiaries, today reported net income determined in accordance with generally accepted accounting principles in the United States of America (GAAP) for the fiscal year ended September 30, 2011 of $117.1 million, or $2.28 per share, compared to net income of $109.9 million, or $2.16 per share, reported for the fiscal year ended September 30, 2010.

For the quarter ended September 30, 2011, we reported a net loss determined in accordance with GAAP of $(30.6) million, or $(0.60) per share, compared to a net loss of $(26.1) million, or $(0.51) per share, reported for the same quarter of the prior fiscal year. Reporting a net loss for quarters ended September 30 is typical due to the seasonal nature of our utility operations and the corresponding reduced demand for natural gas during this period.

Financial performance is also evaluated based on non-GAAP operating earnings (loss). Non-GAAP operating earnings (loss) excludes the effects of: (i) unrealized mark-to-market gains (losses) on energy-related derivatives; (ii) certain gains and losses associated with optimizing the utility segment’s system capacity assets and (iii) certain unusual transactions. Refer to “Use of Non-GAAP Operating Earnings (Loss)” and supporting reconciliations attached to this news release for a detailed discussion of management’s use of this non-GAAP financial measure, as well as reconciliations of net income determined in accordance with GAAP to non-GAAP operating earnings (loss) for both our consolidated and segment results.

For the fiscal year ended September 30, 2011, non-GAAP operating earnings were $115.5 million, or $2.25 per share, compared to non-GAAP operating earnings of $115.0 million, or $2.27 per share, for the prior fiscal year. For the fourth quarter of fiscal year 2011, our non-GAAP operating loss was $(13.4) million, or $(0.26) per share, compared to a non-GAAP operating loss of $(14.8) million, or $(0.29) per share, for the same quarter of the prior fiscal year.

“Strong performance in our retail energy-marketing segment and our ongoing focus on cost control helped us to deliver annual earnings that exceeded our most recent guidance, recovering to 2010 levels,” said Terry D. McCallister, Chairman and Chief Executive Officer of WGL Holdings. “I am pleased with this achievement in light of the headwinds we’ve faced this year from increased pension and operating costs, and given the amount of time that has passed since our last rate adjustments. We have also continued to make investments to support our strategy of delivering clean and efficient energy solutions, recently announcing an investment of up to $30 million in an agreement with Skyline Innovations to install and own commercial-scale solar water heating systems. We now look forward to further earnings improvements in 2012 as we conclude rate cases in Maryland and Virginia and continue to benefit from the growth of our non-utility businesses.”

Fiscal Year and Fourth Quarter Results by Business Segment

Regulated Utility Segment

For the fiscal year ended September 30, 2011, our regulated utility segment reported net income of $69.2 million, or $1.35 per share, compared to net income of $101.7 million, or $2.00 per share, for the prior fiscal year. Net income for the 2011 fiscal year was impacted by one-time adjustments in the fourth quarter as a result of charges associated with regulatory proceedings. After adjustments, non-GAAP operating earnings for the regulated utility segment were $86.2 million, or $1.68 per share, for the fiscal year ended September 30, 2011, compared to non-GAAP operating earnings of $96.0 million, or $1.89 per share, for the prior fiscal year. The year-over-year comparisons of non-GAAP operating earnings reflect: (i) higher employee benefit expense due to changes in pension and retiree medical plan valuation assumptions; (ii) the impact of the reduction in the Maryland depreciation rates effective on June 1, 2010, creating a timing difference between the recognition and recovery of depreciation expense in 2010; (iii) higher depreciation expense due to the growth in, and mix of, our investment in utility plant; (iv) higher costs for weather protection products related to the District of Columbia; (v) a comparison to 2010 results which were favorably impacted by a one-time retroactive recovery of hexane costs and (vi) higher operating expenses primarily attributable to system software upgrades and workforce planning initiatives. Partially offsetting these unfavorable variances were: (i) higher revenues from an increase in average active customer meters of more than 9,800 over the same twelve month period of the prior fiscal year; (ii) a decrease in recurring business process outsourcing costs and (iii) a decrease in incentive plan benefit costs.

For the quarter ended September 30, 2011, our regulated utility segment reported a seasonal net loss of $(38.4) million, or $(0.75) per share, compared to a net loss of $(19.6) million, or $(0.38) per share, reported for the fourth quarter of the prior fiscal year. After adjustments, the non-GAAP operating loss for the regulated utility segment was $(24.2) million, or $(0.47) per share, for the quarter ended September 30, 2011, compared to a non-GAAP operating loss of $(19.1) million, or $(0.37) per share, for the same quarter of the prior fiscal year. This three month comparison of non-GAAP operating earnings reflects: (i) higher employee benefit expense due to changes in pension and retiree medical plan valuation assumptions; (ii) higher depreciation expense due to the growth in, and mix of, our investment in utility plant and (iii) a comparison to 2010 results which were favorably impacted by a one-time retroactive recovery of hexane costs. Partially offsetting these unfavorable variances was lower uncollectible accounts expense which was associated with a reserve adjustment recorded in the prior year.

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Retail Energy-Marketing Segment

For the fiscal year ended September 30, 2011, the retail energy-marketing segment reported net income of $48.8 million, or $0.95 per share, an increase of $37.7 million, or $0.73 per share, over net income of $11.1 million, or $0.22 per share, reported for the prior fiscal year. Non-GAAP operating earnings for the retail energy-marketing segment were $34.1 million, or $0.67 per share, for the fiscal year ended September 30, 2011, an increase of $11.3 million, or $0.22 per share, over non-GAAP operating earnings of $22.8 million, or $0.45 per share, for the prior fiscal year. For the quarter ended September 30, 2011, the retail energy-marketing segment reported net income of $6.0 million, or $0.12 per share, an increase of $11.7 million, or $0.23 per share, compared to a net loss of $(5.7) million, or $(0.11) per share, reported for the same quarter of the prior fiscal year. Non-GAAP operating earnings for the retail energy-marketing segment were $11.7 million, or $0.23 per share, for the quarter ended September 30, 2011, an increase of $5.8 million, or $0.11 per share, over non-GAAP operating earnings of $5.9 million, or $0.12 per share, for the same quarter of the prior fiscal year.

The differences between GAAP net income and non-GAAP operating earnings are due to adjustments to eliminate unrealized mark-to-market gains and losses attributable to certain wholesale energy supply and retail sales contracts. For both the fiscal year and quarter comparisons, the increase in non-GAAP operating earnings reflects higher realized natural gas and electricity margins, partially offset by higher general and administrative expenses. The increase in natural gas sales margins for the fiscal year is primarily attributed to higher gas sales volumes driven by customer growth and higher unit margins related to colder weather and higher wholesale deliveries. For the quarter, natural gas margin improvements were driven by customer growth and favorable timing on the recognition of margins compared to the prior year. Electric sales margins increased for the full year and fourth quarter primarily due to higher sales volumes driven by customer growth as well as favorable weather and pricing conditions in 2011.

Design-Build Energy Systems Segment

For the fiscal year and quarter ended September 30, 2011, the design-build energy systems segment reported modestly profitable results which contributed approximately $0.01 per share for both periods. This compares favorably to the minor loss of approximately $(0.01) per share, for both the prior fiscal year and the same quarter last year. The increase in earnings in fiscal year 2011 is primarily due to the commencement of project work for government agency customers that was delayed in the prior year. There were no non-GAAP adjustments for this segment for any of the periods presented.

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Other Activities

Other activities included unallocated net costs of the parent company and the operating results of Capitol Energy Ventures and other investments that were not considered operating segments. For the year ended September 30, 2011, other activities reported a net loss of $(1.4) million, or $(0.03) per share, compared to a net loss of $(2.3) million, or $(0.05) per share, for the prior fiscal year. For the quarter ended September 30, 2011, other activities reported net income of $1.5 million, or $0.02 per share, an increase of $2.1 million, or $0.03 per share, compared to a net loss of $(0.6) million, or $(0.01) per share, for the same period of the prior fiscal year. After adjustments to eliminate mark-to-market gains and losses, the non-GAAP operating loss for other activities was $(5.4) million, or $(0.11) per share, for the year ended September 30, 2011, compared to an operating loss of $(3.1) million, or $(0.06) per share, for the prior fiscal year. For the quarter ended September 30, 2011, other activities reported non-GAAP operating losses of $(1.3) million, or $(0.03) per share, compared to $(1.5) million, or $(0.03) per share, for the same period of the prior fiscal year. Non-GAAP operating losses for the year were higher than in the prior year principally due to higher initial expenses associated with activities of our non-utility wholesale energy company, Capitol Energy Ventures that are expected to contribute revenues in subsequent periods.

Earnings Outlook

Our GAAP earnings estimate for fiscal year 2012 is in a range of $2.63 per share to $2.75 per share. This estimate includes projected fiscal year 2012 earnings from our regulated utility segment in a range of $1.81 per share to $1.87 per share and projected fiscal year 2012 earnings from our unregulated business segments in a range of $0.82 per share to $0.88 per share.

We are also providing a consolidated earnings estimate for fiscal year 2012 based on non-GAAP operating earnings in a range of $2.46 per share to $2.58 per share. This estimate includes projected fiscal year 2012 non-GAAP operating earnings from our regulated utility segment in a range of $1.80 per share to $1.86 per share, and projected fiscal year 2012 non-GAAP operating earnings from our unregulated business segments in a range of $0.66 per share to $0.72 per share. Refer to the “Reconciliation of GAAP Earnings Guidance to Non-GAAP Earnings Guidance” attached to this press release for a reconciliation of our GAAP earnings per share estimate to our estimate based on non-GAAP operating earnings per share.

We assume no obligation to update this guidance. The absence of any statement by us in the future should not be presumed to represent an affirmation of this earnings guidance. For the assumptions underlying this guidance, please refer to the slides accompanying our webcast that will be posted to the WGL Holdings website, www.wglholdings.com.

Other Information

We will hold a conference call at 2 p.m. Eastern time on November 21, 2011, to discuss our fourth quarter and fiscal year 2011 financial results. The live conference call will be available to the public via a link located on the WGL Holdings website, www.wglholdings.com. To hear the live webcast, click on the “Webcast” link located on the home page of the referenced site. The webcast and related slides will be archived on the WGL Holdings website through December 21, 2011.

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Headquartered in Washington, D.C., WGL Holdings, Inc. has three operating segments: (i) the regulated utility segment which primarily consists of Washington Gas, a natural gas utility that serves over one million customers throughout metropolitan Washington, D.C., and the surrounding region; (ii) the retail-energy marketing segment which consists of Washington Gas Energy Services, Inc., a third-party marketer that competitively sells natural gas and electricity and (iii) the design-build energy systems segment, which consists of Washington Gas Energy Systems, Inc., a provider of design-build energy efficiency solutions to government and commercial clients. Additional information about WGL Holdings, Inc. is available on our website, www.wglholdings.com.

Unless otherwise noted, earnings per share amounts are presented on a diluted basis, and are based on weighted average common and common equivalent shares outstanding.

Please see the attached comparative statements for additional information on our operating results. Also attached to this news release are reconciliations of net income determined in accordance with GAAP to non-GAAP operating earnings (loss) for both our consolidated and segment results as well as reconciliations of our GAAP earnings guidance to our non-GAAP earnings guidance.

Forward-Looking Statements

This news release and other statements by us include forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 with respect to the outlook for earnings, revenues and other future financial business performance or strategies and expectations. Forward-looking statements are typically identified by words such as, but not limited to, “estimates,” “expects,” “anticipates,” “intends,” “believes,” “plans,” and similar expressions, or future or conditional verbs such as “will,” “should,” “would,” and “could.” Although we believe such forward-looking statements are based on reasonable assumptions, we cannot give assurance that every objective will be achieved. Forward-looking statements speak only as of today, and we assume no duty to update them. Factors that could cause actual results to differ materially from those expressed or implied include, but are not limited to, general economic conditions and the factors discussed under the “Risk Factors” heading in our most recent annual report on Form 10-K and other documents we have filed with, or furnished to, the U.S. Securities and Exchange Commission.

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WGL Holdings, Inc.

Consolidated Balance Sheets

(Unaudited)

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WGL Holdings, Inc.

Consolidated Statements of Income

(Unaudited)

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WGL Holdings, Inc.

Consolidated Financial and Operating Statistics

(Unaudited)

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WGL HOLDINGS, INC.

USE OF NON-GAAP OPERATING EARNINGS (LOSS)

(Unaudited)

The attached reconciliations are provided to clearly identify adjustments made to net income calculated in accordance with GAAP to derive non-GAAP operating earnings (loss). Management believes non-GAAP operating earnings (loss) provides a more meaningful representation of our earnings from ongoing operations by adjusting for the effects of: (i) unrealized mark-to-market gains and losses from energy-related derivatives; (ii) certain gains and losses associated with optimizing the utility segment’s capacity assets and (iii) certain unusual transactions. This presentation facilitates analysis by providing a consistent and comparable measure to help management, investors and analysts better understand and evaluate our operating results and performance trends, and assist in analyzing period-to-period comparisons. Additionally, we use this non-GAAP measure to report to the board of directors and to evaluate management’s performance.

The economic substance underlying our adjustments to calculate non-GAAP operating earnings (loss) is as follows:

We also exclude valuation adjustments to the carrying value of non-system natural gas storage inventory. This inventory is held solely to support asset optimization transactions. Valuation adjustments to reflect lower-of-cost or market under current accounting standards may not be representative of the margins that will be realized and shared with our utility ratepayers. Non-GAAP earnings reflect actual margins realized based on the unadjusted historical cost in storage when inventory is withdrawn and sold.

There are limits in using non-GAAP operating earnings (loss) to analyze our results, as they are not prepared in accordance with GAAP and may be different from non-GAAP financial measures used by other companies. In addition, using non-GAAP operating earnings (loss) per share to analyze our earnings may have limited value as it excludes certain items that may have a material impact on our reported financial results. We compensate for these limitations by providing investors with the attached reconciliations to net income, the most directly comparable GAAP financial measure.

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WGL HOLDINGS, INC. (Consolidating by Segment)

RECONCILIATION OF GAAP NET INCOME (LOSS) TO

NON-GAAP OPERATING EARNINGS (LOSS)

(Unaudited)

(Footnote references are described on the following page.)

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WGL HOLDINGS, INC. (Consolidated by Quarter)

RECONCILIATION OF GAAP NET INCOME (LOSS) TO

NON-GAAP OPERATING EARNINGS (LOSS)

(Unaudited)