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Passive House - Energy Efficient Buildings

How To Reduce Energy Consumption

How do we reduce the amount of energy we use for heating and cooling our buildings?

Here we look at the concept of Passive House and modified versions of this concept such as Green Building Principles. We also look at Passivhaus and the 5 strategies to reduce energy consumption.

We consider how these ideas are applied in tropical and sub tropical climates when compared to temperate Northern climates.


Passive House

Passive House is a design concept which is applied to house construction in order to dramatically reduce the amount of energy buildings need to keep them comfortable to live in.

The original idea of Passive House is to use natural means to regulate the temperature within a building. Natural means involved the use of a number of strategies including the following:

  • Careful selection of the site for altitude and aspect.
  • Study of the sun's position in the sky at different times of the year.
  • Orientation of the building in the most advantageous direction.
  • Making full use of sunshine to heat the building.
  • Making use of prevailing winds for natural ventilation.
  • Finding ways to expose or shield the building according to the time of year.
  • Use of insulation to prevent heat gain or loss.
  • Design of windows to capture or reflect heat.
  • The use of canopies and/or screens to manage exposure to sunshine and winds.

Passivhaus

The original Passive House concept lead to the development of a modified concept known as "Passivhaus" which is managed by the "Passivhaus Institut" based in Darmstadt, Germany. Passivhaus focusses on reducing energy consumption using five design and construction principles.

The "Passivhaus" and its certification processes have, in fact, become an industry in themselves with the creation of a worldwide network of consultants, architects and inspectors who pay to be trained and certified so they can charge fees to advise, design and certify buildings.

Environmentally Responsible Housing

Time is moving on and developments continue with broader based concepts emerging that take holistic approaches to the construction of buildings. These developments not only reduce the energy the building requires to function but also consider the environmental damage caused during building construction, they incorporate strategies that protect and enhance the world’s climate and environment. Such initiatives aim to address issues such as the considerable amount of energy needed to produce and transport cement, steel and other construction materials.

The Green Product Council of Indonesia is typical of a new generation of organisations across the world. It is a non government, non profit based organisation committed to environmental responsibility in building design and construction.

These initiatives are being widely applied across the world and have resulted in the creation of new industries manufacturing specialist products such as construction materials that are less damaging to the environment and energy saving building components such as heat and draft insulating materials for roofs, walls, floors, windows and doors.

Five basic Building Design Principles

Passivhaus principles incorporate five ways of saving energy. The aim is to reduce energy consumption by as much as 90%.

  1. Optimised Building Orientation.
  2. Insulated Envelope.
  3. Airtight Envelope.
  4. Elimination of Thermal Bridges.
  5. Mechanical Ventilation.

1. Optimised Orientation

By considering the track and elevation of the sun, the direction a building faces and the placement of windows and doors has a considerable impact on how much heat from the sun’s rays a building will absorb and how much cooling can be harnessed from prevailing winds. By carefully considering these factors in the building design major energy savings are made.

2. Insulated Envelope

Insulation prevents the passage of heat into or out of a building through roof, walls, floors, windows and doors. Insulation can be added to a building in the form of insulation materials or incorporated by carefully selecting the building materials themselves.

3. Airtight Envelope.

Anyone who has lived in a cold climate knows how even the warmest of rooms can be quickly chilled by drafts mostly through windows or under doors. Passive house design seeks to totally eliminate air leakage into or out of the building through the use of non air permeable construction materials and the use of sealing tape in joints. Pressure testing of buildings is used to find air leakages and to measure how airtight they are.

4. Elimination of Thermal Bridges.

Anything that directly connects between the exterior and interior surface of a building can transfer heat. This is especially the case with metal components such as copper or aluminium pipes, window frames and even door handles. Clever design and selection of materials can avoid thermal bridges and greatly reduce energy loss.

5. Mechanical Ventilation

Passivehaus principles include the use of energy driven mechanical ventilation systems that are designed to allow free airflow into and out of buildings while saving energy by transferring heat between the incoming and outgoing air.

Insulation "R Values"

R Values have become a key tool in Passive House design. They are used to allow designers and building certifiers to estimate the effectiveness of these five principles and allow certification to be carried out based on objectively calculated results.

R values can be determined for whole buildings as well as for the materials used to build them. You can find an explanation of Insulation R Values along with a list of typical R values for construction materials in our recent article https://www.mrfixitbali.com/insulation-and-r-values.html

The Passive House In Temperate Climates

The passive house concept was originally conceived in Northern Europe where the aim is to keep buildings warm by harnessing the suns rays and reducing heating costs.

The whole concept is to create a self contained space which is totally isolated from the external environment. In such climates the temperature difference between the interior and exterior of a building may be as much as 30 degrees C (in places such as Canada temperature difference can be much much higher) and especially between day and night. Humidity is not such an issue as it is dealt with by heating which dries out the air.

The Passive House In Tropical Climates

Tropical climates are quite different, temperatures don’t vary anywhere near as much and the challenge of dealing with humidity is not an easy problem to solve. Creating comfortable living spaces is often achieved through the use of open, ventilated building design that makes use of prevailing breezes and natural convection currents. Difficulties do arise on hot days when the air is still and temperatures build up.

The best solution for hot climates is to design buildings that combine the two approaches with airy open living areas that have high ceilings and other rooms, such as workrooms and bedrooms, that follow Passive House principles. Small spaces that are airtight and have high levels of insulation can use very small air conditioners to dry the air and cool the space.

A Small Effort Can Yield Big Gains

Do you need to go full Passive House?

In a word, no.

Going full Passive House is best with new building design and construction. Full Passive House retrofitting of existing buildings can be both expensive and technically challenging. In addition the certification process for buildings can be expensive is is not necessary.

It is not difficult to reduce energy consumption by using some straightforward techniquesand a bit of common sense.

If you are considering building or renovating a building you might not be able to achieve the 90% energy savings that Passive House can yield however, by considering the R values of the materials you select and incorporating some of the five principles above, it is not difficult to make some significant financial savings on your energy bills.


Copyright © Phil Wilson January 2022
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