**2. Incentive policies**

Substantial policies and regulations have been provided to support the installation of RES power plants and thus simulate the widespread of ZEB applications. Under the support of these policies, an increasing number of ZEB case studies have been conducted, and there are over 360 ZEB projects which had been identified in different countries till 2013, as shown in **Figure 3**.

The continued growth in ZEB projects is mainly driven by the progressive financial incentives on renewable energy promotion, which is summarized for several countries from different parts of the world, as shown in **Table 1**. The main support policies on RES in different countries are described as follows [6]:

• Investment subsidies: Based on a percentage of the renewable energy output or the specific investment upfront cost.

#### **Figure 3.**

*World map of more than 360 internationally known net-zero energy buildings [20].*


*O, existing national (may also include state/provincial);* •*, existing subregional (e.g., state/provincial); R, revised (\*indicates state/provincial).*

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*Definition and Design of Zero Energy Buildings DOI: http://dx.doi.org/10.5772/intechopen.80708*

ducer does not use back into the grid.

electricity fed into the grid.

**3. Design methodologies**

**3.1 Design step**

• Feed-in tariff: The producer receives total payments per kWh of generated elec-

• Net-metering schemes: Net-metering (NM) and self-consumption (SC) schemes. Billing agreement between utilities and their customers to feed electricity the pro-

• Tradable Green Certificates: Certificates that can be sold in the market, allowing RES generators to obtain revenue, in addition to the earnings from the sale of

Although no exact approach has been developed for the target of zero balance during the design phase of ZEB, there are still some consensus and several common design elements for designing ZEB. A thorough design approach was proposed which involves 12 steps containing four foundational procedures, that is, applied metrics (e.g., primary energy, the cost), passive design (e.g., building envelope, orientation), active design (e.g., HVAC, lighting), and renewable energy system design (e.g., photovoltaic panel, wind turbine) for the design of ZEB [22, 23], as shown in **Figure 4**. Theoretically, design optimization of ZEB should be conducted considering the three vital design steps, that is, steps 7, 8, and 9, simultaneously to obtain a comprehensive combined design option for ZEB. Therefore, design optimization

Passive design is an important procedure to reduce the building energy demand as much as possible. Then, high-efficiency active energy systems such as heating, cooling, and ventilation systems and lighting systems should be applied and improved together with high-performance control strategies; these could further reduce operational energy consumption in the building. Lastly, the feasibility of renewable energy technology should be assessed and selected as an on-site power supply system which works together with the power grid to reach the target of zero energy demand.

Various software tools have been developed to facilitate the selection of passive design, active design, and RES for buildings; several popular software are listed and compared in **Tables 2** and **3**. In ZEB design, the building energy demand can be firstly evaluated by using building energy simulation software such as EnergyPlus or TRNSYS. The selection of suitable renewable energy system for the building can then be conducted in software such as HOMER and TRNSYS. The design optimization software, HOMER, is developed by the US National Renewable Energy Laboratory (NREL) to assist in design optimization of hybrid energy systems for both grid-connected and autonomous building based on net present cost [24–27]. However, HOMER can only address a single-objective function for minimizing the

It is important to determine the evaluation criteria at the design stage. Various criteria have been proposed from a different perspective of users, which can be classified into four aspects covering technical and environmental issues, economic factors, and the interaction between building and grid, as shown in **Figure 5**.

for ZEB is usually solved by integration of two or more software.

net present cost, and it cannot solve multi-objective problems [28].

**3.2 Performance evaluation criteria**

tricity at a fixed price. It is guaranteed by the government.

#### **Table 1.**

*Promotion policies of renewable energy in several countries [21].*

