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Assessing Renewable Energy Options

Preliminary Screening with an arrow pointing down to Screening.Square with the text planning in the center.
A graphic of an arrow pointing down to Feasibility Study. The word Screening appears on the arrow.A square graphic showing the text Programming: Planning Charette and it's aligned to the right of arrow pointing down which reads Screening.
An arrow pointing down which reads Feasibility Study. The arrow points to Size and Design Systems.A square graphic with the text Building Design: Schematic Design (35%) shown to the right of an arrow pointing down which reads Feasibility Study.
An arrow pointing down which reads Size and Design Systems. This is the last of 4 arrows which show the progression from Preliminary Screening to Screening to Feasibility Study to Size and Design Systems.A square graphic which reads Building Design: Design Development (65%). This is the last of 4 boxes.
Renewable energy can be used most effectively
in a construction project when technology
options are assessed in parallel with the planning
and design process.

Federal agencies should assess renewable energy options for each specific project when integrating renewable energy in new building construction or major renovations. This section covers the preliminary screening, screening, feasibility study, and sizing and designing systems phases.

This overview page describes the phases of the renewable energy assessment process that occurs in parallel with the normal development of a project. Links to deeper-level information are also provided to help agencies assess their renewable energy options.

Almost any location can use renewable energy technologies. However, not every form of renewable energy may be practical at a particular site. Determining which technology or combination of technologies is best suited to a specific construction project is done during the assessment process. This section describes the entire assessment process and details how this process fits into the overall construction project timeline. In general, the practicality of most renewable energy technologies increases when considered early in the planning stages of site and building design.

Narrowing the choices of renewable energy options involves several steps:

Aerial photo of a building with an area of the roof covered in PV panels, arranged tightly around other structures that from the air appear to be small sheds and access structures.
This downtown Boston building showcased
building-integrated PV featuring 372 panels.

Renewable energy technologies can be considered and incorporated at every stage in the design process. However, significant factors that enable cost-effective and technologically-feasible implementation of renewable technologies are often determined in the early design phases. It is prudent to consider and start analyzing the potential for these technologies in the very early, conceptual stages of design.

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Preliminary Screening

The first step in assessing renewable energy options is to conduct a preliminary screening to distinguish between technologies that are worth reviewing and those that should be eliminated without further analysis. This step should occur early in the planning of a construction project. Preliminary screening involves resource maps and other basic tools to choose technologies to pursue further. For additional information, see the preliminary screening section.

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The next step in assessing renewable energy options is a full screening. The screening is usually performed by an outside party or an independent renewable energy expert. It is a review of the possible technology options that identifies dead-ends and further narrows the list to probable technologies for the project. This is a more detailed look at the available resources and a high-level analysis of expected costs and savings, utility considerations, and potential incentives. This screening can also assess each technology's ability to contribute to energy goals and requirements. The agency can analyze specific sites or screen across properties to decide which areas have the greatest renewable energy potential.

Screening should be completed during the programming phase of the project, as it is needed to inform early design decisions and project requirements. It is also very helpful in establishing early budget life-cycle cost estimates for renewable energy.

For details on the screening process, see the screening section.

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Renewable Energy Feasibility Study

Photo of the wall of a building with a large portion covered with dark colored solar PV material.
A new "solar wall" and new HVAC equipment are
saving energy and money at the NASA Dryden
Flight Center, EAFB.

Once an agency has identified probable technologies, a detailed review of the feasibility and economic viability of each renewable energy technology, also called a renewable energy feasibility study, can determine which renewable energy technologies most effectively meet the agency's energy requirements and goals.

The renewable energy feasibility study takes a deeper look into the remaining technologies to quantify how much energy each technology could produce or offset; reviews details of utility interconnection, tariffs, and revenue; analyzes access to financial incentives as well as project funding models; and reviews National Environmental Policy Act (NEPA) requirements, permitting requirements, and operational costs. This assessment can be accurately conducted only after a potential location has been chosen for the project and initial estimates for energy loads and usage exist. Ideally, the feasibility study is conducted before the schematic design phase.

For details on the feasibility study, see the feasibility study section.

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Size and Design Systems

Following the renewable energy feasibility study, the technologies to be included in the new construction project will be defined and the design team will be ready to size and design the systems. At this point in the process, building energy loads and demands will largely be known. Utility requirements and all applicable codes and standards will also need to be considered and met at this stage. This is the last step in the process of assessing renewable energy options.

Integrating renewable energy into a construction project must be in the hands of renewable energy experts and closely coordinated with the overall project design team. For details on sizing and designing systems, see the design development section.

Assessment Factors
Assessing technology options involves examining several factors:

  • Available renewable resources: Renewable energy technologies rely on resources like sunlight, wind, biomass, or heat from the earth. Some technologies require a threshold level of a resource to be feasible or cost effective.

  • Available space: Many technologies require additional space, either on a roof or on land, to function properly.

  • Technology costs: The cost of any renewable energy technology system is calculated along with its potential energy output to estimate its economic feasibility.

  • Energy costs: Estimating the economic feasibility of technologies includes calculating the expected costs of energy to the project that will be offset.

  • Ability to connect to the grid: When incorporating an electric power technology system into a project, the system will typically need to be interconnected with the utility power grid. The rules vary by state and utility as to what size and type of technologies can be interconnected economically.

  • Agency goals: Agency energy goals are important in assessing various technologies. Federal agencies can set goals or mandates, or they could be required by legislation, to incorporate renewable energy into their energy use portfolio.

  • Available incentives: Any financial incentives, such as grants, favorable tariffs, or net metering, can affect the economic feasibility of various technologies.

  • Additional Factors: Other considerations that can affect renewable energy decisions include energy security requirements, zoning, permitting, and environmental review requirements.

The depth at which each factor is considered varies depending on whether the analysis is for a preliminary screening, a full screening, or a feasibility study. Project location solidifies a few variables—including renewable resources, land availability, conventional energy cost, available incentives, local net metering, and interconnection policies. In the early design phases, however, several factors are not yet defined and should be considered. These include orientation and siting of a building on a lot, design of a building to optimize access to the renewable resource, and sizing of a renewable energy system to offset an optimum amount of site energy load and to minimize usual energy purchases (while maximizing the applicability of financial incentives, if applicable).

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