Design and operation of low energy consumption passive solutions – for human comfort

The focus of the world’s attention on environmental issues in recent years has stimulated a response in many countries, which has led to a closer examination of energy conservation strategies. The article explains that one way to reduce building energy consumption is to design buildings that are more economical in their use of energy for heating, lighting, cooling, ventilation, and hot water supply. However, exploiting renewable energy in buildings will contribute to ameliorating environmental conditions that produce no air pollution or greenhouse gases.

This study describes various designs of low-energy buildings. It also outlines the effect of dense urban building nature on energy consumption and its contribution to climate change. Measures which would help to save energy in buildings are also presented. The use of renewable energy sources will be a fundamental factor in energy policy in the future. Considering the sustainable character of most renewable energy technologies, they preserve resources and provide security and diversity of energy supply and services virtually without environmental impact. Sustainability has acquired great importance due to the negative influence of developments on the environment.

Natural resources may be renewable, non-renewable, or abstract. Non-renewable resources include fossil fuels, minerals, clear-felled tropical hardwoods that are not replaced, and rare animals or plants that are hunted or collected uncontrolled.

In many countries, global warming considerations have led to efforts to reduce fossil energy use and to promote renewable energies in the building sector. To keep the environmental impact of a building at sustainable levels – by greenhouse gas (GHG) neutral emissions – the residual energy demand needs to be covered with renewable energy. Integrative concepts for buildings with excellent indoor environment control and sustainable environmental impact are presented here. Special emphasis is put on ventilation concepts, utilising ambient energy from the air, the ground and other renewable energy sources, and the interaction with heating and cooling.

The heating or cooling of a space to maintain thermal comfort is a highly energy-intensive process accounting for as much as 60-70% of total energy use in non-industrial buildings. Approximately 30-50% is lost through ventilation and air infiltration. However, estimation of the energy impact of ventilation relies on detailed knowledge of air change rates and the difference in enthalpy between the incoming and outgoing air streams. The design and implementation of energy-efficient passive solutions for optimal human comfort with minimal power consumption and sustainable environmental integration include many parameters.

Comfort temperatures and climate

Nearly half the world’s energy use is associated with providing environmental conditioning in buildings, and about two-thirds of this is for heating, cooling and mechanical ventilation. While in cooler climates, the energy used for heating is minimised, with the application of conservation technologies, energy requirements for cooling are increasing. The passive cooling techniques applications to buildings in warm climates create the need for appropriate comfort criteria. The perceived need for mechanical cooling is to achieve accepted thermal comfort standards, usually defined (directly or indirectly) by temperature limits. There is, however, growing controversy as to what these standards are. For example, in a compilation of results from 47 field studies, predominantly in warm and hot climates, Humphrey (1978) found that the preferred comfort temperature in buildings was a function of the average monthly outdoor temperature:

 

Tn = 0.534 To + 11.9                                                                                                                      

Where,

Tn is the indoor comfort temperature, and To is the mean of the local daily maximum and daily minimum outdoor temperatures at the appropriate seasons.

Fanger’s theory [18] relates the sensation of hot or cold (Predicted Mean Vote, PMV) and, subsequently, the discomfort or dissatisfaction (Predicted Percentage Dissatisfied, PPD) to the imbalance between the heat produced by the body’s metabolism and the heat loss to the environment. This imbalance cannot exist indefinitely, and the sensation of discomfort signals the person to take some action to restore heat balance.

PMV = (0.303 exp-0.36M + 0.028) (M-H)                                                                                      

And

PPD = 100-95 exp- (0.0335PMV4 + 0.218 PMV2)                                                                       

Where,

M is the metabolic rate, and H is the heat loss to the environment.

Using Fanger’s equations seems to predict the need for more closely controlled conditions than one usually finds in free-running buildings, where people still seem comfortable. For example, ISO 7730, based upon Fanger’s equations, recommends an optimal operative temperature of 24.5oC ± 1.5oC for light sedentary work with light summer clothing.

Energy savings

The admission of daylight into buildings alone does not guarantee that the design will be energy efficient in terms of lighting. The design for increased daylight can often raise concerns about visual comfort (glare) and thermal comfort (increased solar gain in the summer and heat losses in the winter from larger apertures). Such issues should be addressed in the design of window openings, blinds, shading devices, heating systems, etc.  Simple techniques can be implemented to increase the probability that lights are switched off.

These include – making switches conspicuous, locating switches appropriately about the lights, switching banks of lights independently, and switching banks of lights parallel to the main window wall.

Big energy savings involve addressing a broad spectrum of considerations. Implementing guidelines for low-energy design ensures that buildings operate efficiently while reducing environmental impact. A well-balanced approach to natural and artificial lighting enhances energy conservation without compromising comfort. Managing solar gain through shading techniques helps regulate indoor temperatures, reducing the reliance on mechanical cooling. The fenestration design maximises daylight utilisation, reducing heat loss or gain. Energy-efficient plant systems and advanced control mechanisms further optimise energy use. However, assessing the necessity of air conditioning allows for alternative cooling strategies that contribute to overall energy efficiency.

The strategy

• Integration of shading and daylighting: an integral strategy is essential and feasible where daylighting and shading can be improved simultaneously.
• Effect of shading on summer comfort conditions: Solar shading plays a central role in reducing overheating risks and offers the potential for individual control. It should be complemented with other passive design strategies.
• Effect of devices on daylighting conditions: The devices can be designed to provide shading while improving daylight conditions, notably glare and the distribution of light in a space, thus improving the visual quality.
• Energy savings: Energy savings from avoiding air conditioning can be very substantial, while daylighting strategies need to be integrated with artificial lighting systems to be beneficial in terms of energy use.

In summary, achieving low-energy buildings requires a comprehensive strategy that covers building designs and integrally considers the environment around them.

Efficient use of energy

Achieving sustainable development requires a holistic approach that integrates various essential parameters. Buildings should be designed to be climate-responsive, ensuring they adapt to environmental conditions. Good urban planning and architectural design create sustainable and livable spaces. Incorporating sound housekeeping and design practices improves sustainability efforts.

Passive design strategies, including natural ventilation, contribute to reducing energy consumption, while landscaping can serve as a tool for thermal control. Energy-efficient solutions, such as advanced lighting systems, air conditioning, and household and office appliances, significantly minimise energy wastage. Integrating heat pumps, energy recovery equipment, and combined cooling systems optimises energy use. Additionally, the development of fuel cells offers advancements in sustainable energy solutions.

Conclusion

With environmental protection posing the number one global problem, man has no choice but to reduce energy consumption. One way to accomplish this is to resort to passive and low-energy systems to maintain thermal comfort in buildings. The conventional and modern designs of wind towers can successfully be used in hot, arid regions to maintain thermal comfort (with or without ceiling fans) during all hours of the cooling season or a fraction of it. Climatic design is one of the best approaches to reduce building energy costs.

Proper design is the first step in defence against the stress of the climate. Buildings should be designed according to the climate prevailing on the site, reducing the need for mechanical heating or cooling. The maximum natural energy can create a pleasant environment inside the built envelope. Technology and industry progress in the last decade have diffused electronic and informatics devices in many human activities and in building construction.

The utilisation and operating opportunities components increase the reduction of heat losses by varying the thermal insulation, optimising the lighting distribution with louvre screens and operating mechanical ventilation for coolness in indoor spaces. In addition to these parameters, the intelligent envelope can act for security control and has become a part of the building revolution. Applying simple passive cooling measures effectively reduces the cooling load of buildings in hot and humid climates. 43 percent reductions can be held using well-established technologies such as glazing, shading, insulation, and natural ventilation. The building sector is a major consumer of both energy and materials worldwide, and that consumption is increasing.

It is necessary to change and develop the industry’s processes to achieve the major changes needed to alleviate the building sector’s environmental impacts and build a favourable framework to overcome the present economic, regulatory, and institutional barriers.