With the advent of 21st century, the world faces serious interlinked energy and environmentally challenges. The problem with generation and excessive consumption of energy causes environmental issues included global warming, air pollution, deforestation, ozone depletion and radioactive waste .
The consumption of fossil fuels is the major causes of greenhouse gases which increased the percentage of CO2 emission , statistics suggest that over the last three decades, energy demand and CO2 emissions in the world have grown by 89.5% and by 79% respectively( Elkinton , 2009). The buildings sector is a major source of energy consumption , commercial and residential buildings consume about 40% of the primary energy consumption . ( D.Streimikiene , 2104 ).
Efforts are being made all around the world to develop energy efficient buildings by developing the term of net zero energy buildings.The climate in jordan is a combination between arid desert and mediterranean in north and west of jordan ,and mostly of climate is desert .Climate conditions are immensely important both in terms of energy consumption buildings and the potential for renewable energy.
Daytime temperatures during the summer months frequently exceed 36 °C (96.8 °F) and average about 32 °C (89.6 °F). In contrast, the winter months—November to April—bring moderately cool and sometimes cold weather, averaging about 13 °C (55.4 °F).
(UNFCCC ,2014)The high values of solar energy radiation illustrate that the solar energy exploitation in Jordan is possible and gives better results than that in other countries ( Al zou’bi , 2010) Concerning wind energy resources in Jordan, there are tens of places known by their high wind speed and long windy times . ( Al zou’bi , 2010 )Trends in Jordan and throughout the world have motivated builders to build low energy use, environmentally friendly and affordable, or at least more economical homes. A Goal of net zero energy to reduce consumption of energy by clean and renewable source for the energy after energy consumption has been reduced as much as is feasible.The main focus of this review was to find literature that expressed systems and designs need that reduce energy consumption in residential buildings.The study describes the general approach to design net zero energy houses and describe the specific strategies used in the architectural design of the NZEb that promote low energy use, good indoor air quality, durability, minimal environmental impact, and net-zero energy capability.
1.1 What is a net-zero energy houses? link between energy efficient technology and renewable energy utilization That energy generated on site use renewable energy. Builder, owner, architect engineer all around the world have to build homes with efficiency energy and clean renewable energy.The concept of net zero energy focus on performance of the building and achieving energy efficiency has centered on integrated technologies as well as ways to connect buildings to the natural environment.(Fanney , Healy , 2015) 2.
Aspects of Net-Zero energy building The study identifies aspects of ZEB design and construction that demand further investigation and research, such as life-cycle cost, environmental impact, social policy issues(user behavior) , Design principles and economic viability of zero energy buildings.2.1 Design Principles.Create a framework of development of net zero energy to clarify the conditions related to location ,microclimate energy sources to get needs and requirement of comfort and energy in all central aspect of design principles.According to (Bejder, Anne Kirkegaard; Knudstrup, Mary-Ann; Jensen, Rasmus Lund; Katic, Ivan; 2014; ” ): Through its building form, its functional layout and the proportioning of rooms, orientation, utilization of daylight and choice of materials, the building will communicate with its users and surroundings. At the same time, the overall building design is essential for the technical performance of the building, e.g.; how much energy is required to heat the building, what is the need for artificial lighting and the possibilities (and effect) of natural ventilation? It is, therefore, essential to perform calculations of the building’s performance throughout the design process, which can inform the design of the building.
2.1.1 SPACE AND FUNCTIONIt is important to include a certain degree of flexibility in the design of the house, taking into consideration the long lifespan of the house, changes in household composition and user needs.2.
1.2 DAYLIGHT SPACE AND FUNCTION it is important from the beginning of the design process to formulate a daylight strategy taking into account both qualitative and quantitative aspects of daylight2.1.
3 VENTILATIONThe primary objective of ventilation is to ensure a good indoor environment with high indoor air quality and pleasant temperatures. Choice of ventilation strategy is of great importance for the building design, for the comfort in the house and for the energy use. a distinction is made between two ventilation strategies; natural and mechanical ventilation.2.1.4 SOLAR SHADING, SPACE AND FUNCTIONExterior solar shading is an efficient way to prevent overheating. Direct solar radiation will be blocked before it enters the room, and the supply of passive solar heat will be reduced.
According to (Jensen & Petersen 2013), exterior solar shading is essential in order to meet the building class 2020 thermal indoor environment requirements and at the same time to ensure good daylight conditions in the house.2.1.
5 HEATINGDesigning the heating system of a zero energy building requires selecting a heat distribution method and a method of supplying each room.2.1.6 MATERIALS AND ACOUSTICSIn order to achieve a sustainable building design, it is important to consider the impact of the building materials on the environment and the surroundings, including the indoor environment and acoustics as well as the user’s sensuous perception of the house.2.1.7 BUILDING ENVELOPE THERMAL MASSThe effect of thermal mass on energy savings and thermal comfort needs extensive investigation, with the coupling of different levels of thermal mass with several night ventilation schedule2.1.
8 BUILDING ENVELOPE, WINDOWS, LIGHT AND HEATOpenings in the building envelope will determine the amount of heat exiting the house as well as heat and light that enter the house; they also provide a view and contact to the surroundings. Low energy windows may vary greatly, and thermal bridges (li- near thermal transmittance) and leakages around windows and doors are relatively important in a highly insulated building envelope (Brunsgaard 2010).3.
Social Issues.social policy issues( user behavior ) according to (KS Judd, 2013;) occupant behavior is one of the aspects that affect on the reduce consumption of energy there are large differences of performance in residential building in spite of same properties and similar conditions . comfort criteria for occupant and their interaction with building envelope affect on related energy uses.The occupant behavior lifestyles and different household have impact on energy use and thermal comfort conditions in a residential nearly zero energy building under-construction. So Designing a house with optimal functionality is one thing, to accommodate requirements of comfort, energy use reduction is promoted as the most important element in moving toward net zero consumption. 4.
CostIn order to activate NZBs cost control to accomplish high efficiency energy performance it is important to assure decision making during the early design phases for NZEBs . Creative designers can integrate simple, passive energy-efficiency strategies into the building architecture without any additional cost, building orientation, massing, and layout can be designed without increasing construction and material cost to reduce building energy loads. Also other passive strategies including thermal massing, natural ventilation, solar shading and daylight redirection could be integrated to the building design to reduce energy consumption with no additional cost. the south-facing daylight redirection is an optimal strategy in architecture building design to accomplish cost-effective, passive efficiency strategies, rather than using adjustable blinds or automatic roller shades to control solar glare using passive fixed light – redirecting device that maximize daylight penetration to reduce solar glare without needing any mechanical component that increase cost of long term maintenance. ( Matt , shanti , paul , 2014 )There are many strategies should implement with following principles to get the most opportunities to control the cost 1- Select a method that increase the importance of energy performance to be on par with other project objectives , including energy efficiency as a minimum requirement in process enhances the invention in the design and construction that is necessary to meet an owner’s goals on a budget.
2- To get cost less and perform better should be emphasize integrated design and team communication, integrated design results in design and construction solutions c. The decisions of construction and Making design as a team limits misunderstandings during construction and ensures that individual expertise is effectively utilized. This level of communication and collaboration is critical to leveraging integrated design principles and implementing cost control strategies.3- Emphasize integrated design and team communication, integrated design results in design and construction solutions that cost less and perform better. Making design and construction decisions as a team limits misunderstandings during construction and ensures that individual expertise is effectively utilized.
This level of communication and collaboration is critical to leveraging integrated design principles and implementing cost control strategies.(NREL , 2014 )5. Renewable energy:Solar energy, most of renewable energy come from sun directly or indirectly..can be used for heating and lighting and generating electricity.
Geothermal energy is the internal heat from earth can be used.Wind Energy. Bioenergy.5.1 Renewable energy technologies.Various supply-side renewable energy technologies are available for ZEBs. there are many technologies available today include PV, wind,solar hot water,biofuels, and hydroelectric. All these renewable sources are appropriate over conventional energy sources such as coal and natural gas , Principles should be taken to develop ranking of renewable energy based it technologies that , 1-By encouraging energy-efficient building designs and reducing transportation and conversion losses that can minimize the environmental impact.
2- Will be available over the lifetime of the building.3- Are widely available and have high replication potential for future ZEBs. ( Torcellini , Pless , Dern , 2006)According to (M. Al zou’bi: 2010; “Renewable Energy Potential and Characteristics in Jordan ,Hijjawi Faculty for Engineering Technology”. A success ZEB definition should first accomplish energy efficiency, and then use renewable energy sources which available on site. A building that has little incentive to reduce building loads because it buys all energy from a wind farm or other location, which is why we refer to this as an off-site ZEB.
Efficiency measures or energy conversion devices such as day lighting or combined heat and power devices cannot be considered on-site production in the ZEB context. ( Torcellini , Pless , Dern , 2006)6. Conclusion:This paper discussed that Net zero energy have many aspect which affect on the reduce of energy consumption.
Getting to zero energy need many design principles. These principles are integrated with renewable energy(solar energy ,wind ,geothermal ) and user behavior .this integration get the framework to reduce emission that change the climate, create comfort healthy environment, minimize the cost and maximize the efficiency.