Energy Efficient Solutions in Modern Buildings

  Introduction

The concept of “energy efficient” buildings has immediate implications on regulations, economics, energy demand, and the environment.  A definition is also needed to compare building energy performance or to assess absolute energy efficiency.  We propose three criteria for an energy efficient building,

1.  The building must be equipped with efficient equipment and materials appropriate for the location and conditions
2.  The building must provide amenities and services appropriate to the building’s intended use
3.   The building must be operated in such a manner as to have a low energy use compared to other, similar buildings.

 An efficient building must, at a minimum, be above average in all three aspects.  When setting minimum efficiency standards, a definition of energy efficiency based on minimum life cycle costs is likely to result in much stricter standards and greater energy savings than a strategy based on eliminating the least efficient units.   

The energy efficiency of buildings is significantly influenced by architectural design aspects, such as orientation, shape of the building structure, where the openings of windows are located, etc. Therefore design team focus is also on energy related design aspects. Especially in tendering procedures for architectural competitions public clients have to take strong notice on these energy related design aspects.

In general there are following strategies for the design of energy efficient buildings:

•   Minimization of losses   
• Minimization of electricity demand for artificial lighting
• Maximization of solar gains – Heating case
•  Minimization of solar gains – Cooling case

Minimization of losses – Compactness

Depending on the building type (housing, office, schools, etc.) transmission losses can have the highest ratio of all losses. Therefore the first design relevant measure should be the reduction of heating losses by minimization of the shape/volume ratio. Especially for an economical realization of passive houses or zero- and plus energy- houses compactness is of highest importance, as worse compactness means higher construction costs (improvement of u-values => more insulation materials => higher costs).

Minimization of electricity demand for artificial lighting

  Besides heating and cooling the energy demand for artificial lighting is of importance for the energetic performance of buildings. Buildings with huge overall width, like office buildings, tend to have substantial energy demand for artificial lighting. The development of innovative daylight concepts is the most important strategy to decrease the energy demand for lighting. Daylight concepts always have to be considered in combination with aspects for heating and cooling.  

Maximization of solar gains – Heating case

 In the heating period a maximization of passive solar gains should be the main target to reduce the heating energy demand. Optimized interaction of orientation, size of windows and disposable thermal mass are the key elements. Special design of windows and a special sunblind with reflector (reflecting sunlight to the ceilings) enables a maximization of solar energy. Massive floors, walls and special designed ceilings (ribbed concrete slabs with large surface area)  be used for the storage of solar energy.

Transparent building elements (windows)

Orientation and size of transparent building elements (windows) have important influence on the cooling demand. Intelligent shading elements with different orientation (e.g. south windows with horizontal elements, west and east windows with vertical elements) are further measures for the reduction of solar gains.

Natural cooling with passive night ventilation

In office buildings up to 2/3 of the total cooling load (around 200 – 250 Wh/m2/day) can be managed by passive cooling without mechanical energy. Night temperature in summer around 15°, adequate thermal building mass and the possibility of natural stack ventilation (e.g. in atriums, see figure below) are requirements for this kind of cooling. 

Natural ventilation by wind

For high rise buildings natural ventilation concepts by wind are innovative alternatives to conventional mechanical ventilation systems. The new office building of the European Central Bank in Frankfurt will be the first office building using only natural ventilation. The design of the building is based on wind and ascending forces around and in the building. 

Active use of solar energy

 Compared to other HVAC-systems active use of solar energy on one hand has strong input on the design of the building and on the other hand the use of solar energy also has strong influence on the environmental performance of the building. The intensive use of solar energy requires a comprehensive integration of solar panels in the architectural design concept and influences the design of buildings strongly. Solar panels can be mounted on walls and roofs, whereas in urban context roofs offer better conditions (less shading by other buildings, free choice of declination enabling higher degrees of efficiency).

Group members (Group 01)

v  Abeywickrama M.G.W.U -152401 T

v  Alahakoon A.M.M.S.B – 162602 U

v  Haafeel M.H.A. -162625 R

v  Liyanaarachchi R.N.H -162645 D

v  Senanayake S.M.A.H – 162668 B