Tag Archives: Thermal Mass

Thermal Comfort and Star Ratings

Thermal Comfort and Star Ratings

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As explained in our previous article: the perception of temperature is more important than the temperature itself, when it comes to comfort.

In Australia, energy rating assessments are done pre-construction, assuming competent application of all insulation and building materials as well as draught sealing all wall penetrations.

However, common construction practices often demonstrate misapplications and air leakages. Sadly, although there are regulations in place on how to install insulation and how to seal of wall penetrations, there is no one really responsible for checking all those details, neither the builder, nor the architect, nor the building surveyor. In fact, some tradies even take out insulation, so that they can work easier around cables, fixtures and fittings and don’t bother to put the insulation back in. For sure, as soon as the plasterboard sheets are one no one can even see the problem.

This means that although in theory the house should be energy efficient, the reality will be far from that. It will be draughty inside. Cold air can come in. The energy bills will be way higher than the energy rating did predict. And, as explained in our article about thermal comfort, it will be hard to feel comfortable inside your ‘well insulated’ home.

In Europe, energy efficiency is most often assessed or checked post construction, with special attention to the prevention of thermal bridges. Some countries require airtight buildings, and amongst other things, double glazing, solar energy for hot water and heating systems, the usage of storm water, greywater recycling, recycled materials and product life cycle considerations to minimise energy demand and carbon footprint.

Conclusion

A good star rating, well performing insulation and building materials are not a guarantee for well performing homes and for feeling comfortable inside the house. The building envelope needs to be treated as a delicate continuous shell. Each small gap and leakage will impair the energy efficiency and the well being of the occupants. It is essential to consider the end product in order to determine how energy efficient a building really is.

The Difference between Air-Leakage & Ventilation

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Ventilation
Ventilation is the active process of “changing” or replacing air to regulate temperature and moisture. It should always occur under controlled conditions, by opening windows or with ceiling or exhaust fans, NOT through gaps and air-leakage. Ventilation is important to support the ability of thermal mass to absorb and release heat in order to regulate the indoor temperature.

It is necessary to ascertain where natural breezes are to locate the windows accordingly. Landscaping and other buildings can influence and obstruct air flow; therefore it is necessary to visit and check the site before locating windows. Cool summer breezes in and around Melbourne usually come from south; detailed information can be found from the Bureau of Meteorology (BOM) web site.
The less gaps and air-leakage occur the air-tighter a building gets. Therefore regular ventilation is mandatory to renew oxygen and discharge odours, water vapour, carbon dioxide and other contaminations.

For instance, in Germany it’s recommended to cross-ventilate every day for a few minutes, even in winter. If the occupants forget to ventilate regularly, water vapour will be trapped inside and will lead to mildew and mould on the walls and the ceilings.

Cross-ventilation
Openable windows and external doors should be located on different sides of the home, with less than 8 metres distance between them to allow for adequate and effective air flow. Cooler air enters the building where the breeze is loctated, passes through the building and exits on the other side. The warm air inside gets replaced by fresh and cooler air.

Thermal Mass and Heating Choices

thermal massIn most European countries, thermal mass is used as a matter of course. Although it takes  longer to heat up a house which contains a lot of thermal mass, it also takes a long time to cool down again. The thermal mass releases constant heat to the rooms and therefore heaters only need to be on a low setting or turned off completely.

Unlike in Australia, split systems and ducted heating are rarely used overseas as they use only convective heat. The main focus lies on radiant heaters as they heat thermal mass. The main form of heating in Europe is hydronic heating, mostly in form of hydronic heating panels, but also as in slab heating. Other sources of radiant heat are wood or gas fire places. Hydronic heating is also way more allergy friendly than ducted heating or split systems. But this is more the subject for a separate blog post.

If thermal mass is combined with effective insulation and has good solar access, the interior is perceived to be comfortable, without the need for additional heating, even if the external temperature is well below 20°C. The combination of thermal mass and well performing insulation is a condition of passive solar design, as well as low and zero-energy housing.

Conclusion
Thermal mass is an effective way to reduce the need for mechanical heating and cooling and to increase the comfort and well-being of the occupants. In order to perform at its best, it needs to be located appropriately and sized adequately, with a careful eye on insulation and thermal bridges.

Thermal Mass: material and colour selection

Material and colour selection

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Generally speaking, the more thermal mass the better and the heavier a material, the better its ability to store heat. The optimum would be a masonry home with a reverse brick veneer construction and concrete floors. Or using something like concrete block walls and insulate at the outside, with isolation boards.

If this option is too expensive use as much thermal mass as possible, concrete slab is preferable. In warmer climates the ground is colder and can help to cool the concrete. Therefore the indoor air temperature will be reduced. In colder climates, however, the concrete slab needs to be insulated from the ground in order to minimise heat loss in winter.  When looking a the energy start rating,  insulating the slab on ground can add up to 1 star to your star rating.

If a timber subfloor is requested or required, the focus should be at least on internal brick walls to the north which need to be exposed to the winter sun and are therefore able to absorb and release heat. Other materials that have a good thermal conductivity are water, sandstone, rammed earth and earth blocks, mud brick etc.

Moreover, colours and coverings can influence the performance of thermal mass. For example carpets and timber floors will minimise the ability of thermal mass to absorb and release heat as they work as additional insulation. This can lower the required heating in winter, but it will increase the need of additional cooling in summer, as the thermal mass can absorb less heat. On the other hand, hard floor finishes such as tiles, stone or slate on concrete slab can increase the ability to store heat. Dark colours or dark materials also tend to absorb more heat, however, light-coloured walls are more desirable as they maximise natural daylight. Dark walls will increase the need of artificial lighting, as they absorb light and can make rooms appear smaller. In short, material and colour selection can promote or adversely affect the performance of thermal mass.

One alternative to adding thermal mass as a actual building material is to add something that acts as thermal mass, but is light weight. There is one product on the Australian market, calle BioPCM. This phase change material acts as thermal mass, without the weight actual thermal mass has, and hence standard light weight construction and footings are sufficient, which are usually significantly cheaper than if you are building with brick and or block work.

“BioPCM™ is a lightweight smart thermal mass, providing design flexibility and easy installation for a cost effective and simple approach to integrating sustainable technology into buildings.
BioPCM™ absorbs excess heat during the day and releases this energy back in the evening as buildings cool.”

 

We have used the BioPCM to line the walls of a pantry, to keep it cooler and create some sort of cool – room. And the result was really great. The room always stays much colder then the rest of the well insulated weatherboard home.

 

 

Optimal Use Of Thermal Mass

How to locate thermal mass

optimal thermal mass
Thermal mass needs to be situated correctly and needs to work in combination with passive solar design and good performing insulation, otherwise it can have negative effects and even increase the need for heating and cooling. Thermal mass should be situated on the interior face of the building envelope and must be thermally separated from the outside via insulative materials.

Thermal mass should be located throughout the building to maintain comfort in summer, but the main focus should be on north-facing rooms. Good solar access is obligatory as the low winter sun needs to be able to enter the building and to strike the thermal mass. The more glass area, the more thermal mass is required.
Thermal mass is extremely important for multi-storey buildings, as warm air rises and therefore the rooms tend to overheat easily. Unfortunately most upper storeys are usually built in lightweight construction, as this is cheaper and easier to build. It is important, however, to incorporate as much thermal mass as possible, for example concrete floors or internal brick walls.

When using thermal mass in upper storey buildings careful attention has to be paid on the details. For instance that there are no structural thermal bridges, which can lead to unwanted heat transfer between the outside and the upper level concrete floors. But also the floors itself need to be insulated, to avoid heat rising up and heating up the upper levels. Insulating concrete floors isn’t a legal requirements, but highly recommended, if you do want to enjoy the thermal benefits and not the negative side effects of thermal mass.

In our next article we will speak about material and colour selections.

How can thermal mass help in Winter or Summer to regulate room temperature?

summer and winter

 

When deciding on what materials to use for your house many only think about factors such as cost and aesthetics. But when it comes to creating an energy efficient home the performance of a material and its ability to store heat needs to be taken into consideration. Thermal mass will help regulate the indoor temperature in summer as well as in winter and will reduce the need of mechanical heating and cooling.

 

Winter benefits

In winter, thermal mass works like a heater: it absorbs radiant heat from the sun through north, east and west-facing windows, and also stores heat from mechanical heating. The thermal mass will slowly release the heat which reduces the need for heating. Even when the heaters are turned off, the house will stay warmer for longer. Furthermore, the air and the exposed surfaces have the same temperature (Mean Radiant Temperature), which means there are no unwanted draughts, and the Relative Air Velocity is low; these will increase the thermal comfort of the occupants.

 

Summer benefits


Materials such as concrete and brick are cooler in summer than the surrounding air temperature, so they are able to absorb heat, which consequently lowers the room temperature and the need for additional cooling. At night the thermal mass will slowly release stored heat. Natural ventilation, via open windows, ceiling or exhaust fans, are an effective way to let cool air in and to let heat – collected during the day – out. In extreme hot periods, when it doesn’t cool down at night, air conditioning may be required to regulate the room temperature. The greater the difference between day and night temperature, the more beneficial the thermal.

 

Please be aware, that a standard brick veneer home will not give you any benefits for your indoor temperature, as the thermal mass is located externally, and separated from the indoor climate via insulation

What is Thermal Mass and why should we use it in construction?

thermal mass

Although the term ‘thermal mass’ is not commonly used, there are many examples where we experience it and appreciate its benefits. The most impressive is the ocean: in winter, when there is less sunshine and the average air temperature is low, the water is chilly and only the tough ones might enjoy a swim! In spring, the sun will slowly heat up the water so that finally in summer it will have a comfortable warm temperature. Water has a great capacity of storing heat – it will stay constantly warm during day and night, and even in winter, it can be significantly warmer than its surrounding air temperature due to its ability to absorb solar energy. Water demonstrates the principle of thermal mass. How does it apply to construction?

 

Thermal Mass, Why Is It So Important for Construction?
Thermal mass is the ability of storing and releasing heat to help retain a constant indoor temperature. It is an effective way to improve thermal comfort in a building and plays an essential role in saving energy. Thermal mass inside a building will absorb heat when the surroundings are warmer than the mass, will store the heat and radiate it slowly when the surroundings are cooler. It can actively be used to regulate temperature, therefore, reducing the need for mechanical heating and cooling. Heavy materials, such as concrete and brick have great thermal storage capacity, whereas lightweight construction materials, such as timber and insulation cannot store heat. Generally speaking, the heavier a material the better its ability to store heat.

If you want to know more about thermal mass please also read our further articles about this subject.

What is Thermal Mass and why do we need it?

Although the term ‘thermal mass’ is not commonly used, there are many examples where we experience it and appreciate its benefits. The most impressive is the ocean: in winter, when there is less sunshine and the average air temperature is low, the water is chilly and only the tough ones might enjoy a swim! In spring, the sun will slowly heat up the water so that finally in summer it will have a comfortable warm temperature. Water has a great capacity of storing heat – it will stay constantly warm during day and night, and even in winter, it can be significantly warmer than its surrounding air temperature due to its ability to absorb solar energy. Water demonstrates the principle of thermal mass. How does it apply to construction?

Thermal Mass, Why Is It So Important?

Thermal mass is the ability of storing and releasing heat to help retain a constant indoor temperature. It is an effective way to improve thermal comfort in a building and plays an essential role in saving energy. Thermal mass inside a building will absorb heat when the surroundings are warmer than the mass, will store the heat and radiate it slowly when the surroundings are cooler. It can actively be used to regulate temperature, therefore, reducing the need for mechanical heating and cooling. Heavy materials, such as concrete and brick have great thermal storage capacity, whereas lightweight construction materials, such as timber and insulation cannot store heat. Generally speaking, the heavier a material the better its ability to store heat.

Summer benefits
Materials such as concrete and brick are cooler in summer than the surrounding air temperature, so they are able to absorb heat,  which consequently lowers the room temperature and the need for additional cooling. At night the thermal mass will slowly release stored heat. Natural ventilation, via open windows, ceiling or exhaust fans, are an effective way to let cool air in and to let heat – collected during the day – out. In extreme hot periods, when it doesn’t cool down at night, air conditioning may be required to regulate the room temperature. The greater the difference between day and night temperature, the more beneficial the thermal mass.

Winter benefits
In winter, thermal mass works like a heater: it absorbs radiant heat from the sun through north, east and west-facing windows, and also stores heat from mechanical heating. The thermal mass will slowly release the heat which reduces the need for heating. Even when the heaters are turned off, the house will stay warmer for longer. Furthermore, the air and the exposed surfaces have the same temperature (Mean Radiant Temperature), which means there are no unwanted draughts, and the Relative Air Velocity is low; these will increase the thermal comfort of the occupants.

Optimal Use Of Thermal Mass

How to locate thermal mass
Thermal mass needs to be situated correctly and needs to work in combination with passive solar design and good performing insulation, otherwise it can have negative effects and even increase the need for heating and cooling. Thermal mass should be situated on the interior face of the building envelope and must be thermally separated from the outside via insulative materials.

Thermal mass should be located throughout the building to maintain comfort in summer, but the main focus should be on north-facing rooms. Good solar access is obligatory as the low winter sun needs to be able to enter the building and to strike the thermal mass. The more glass area, the more thermal mass is required.
Thermal mass is extremely important for multi-storey buildings, as warm air rises and therefore the rooms tend to overheat easily. Unfortunately most upper storeys are usually built in lightweight construction, as this is cheaper and easier to build. It is important, however, to incorporate as much thermal mass as possible, for example concrete floors or internal brick walls.

Material and colour selection
Generally speaking, the more thermal mass the better and the heavier a material, the better its ability to store heat. The optimum would be a masonry home with a reverse brick veneer construction and concrete floors. If this option is too expensive use as much thermal mass as possible, concrete slab is preferable. In warmer climates the ground is colder and can help to cool the concrete. Therefore the indoor air temperature will be reduced. In colder climates, however, the concrete slab needs to be insulated from the ground in order to minimise heat loss in winter.
If a timber subfloor is requested, the focus should be at least on internal brick walls to the north which need to be exposed to the winter sun and are therefore able to absorb and release heat. Other materials that have a good thermal conductivity are water, sandstone, rammed earth and earth blocks, mud brick etc.
Moreover, colours and coverings can influence the performance of thermal mass. For example carpets and timber floors will minimise the ability of thermal mass to absorb and release heat as they work as additional insulation. This can lower the required heating in winter, but it will increase the need of additional cooling in summer, as the thermal mass can absorb less heat. On the other hand, hard floor finishes such as tiles, stone or slate on concrete slab can increase the ability to store heat. Dark colours or dark materials also tend to absorb more heat, however, light-coloured walls are more desirable as they maximise natural daylight. Dark walls will increase the need of artificial lighting, as they absorb light and can make rooms appear smaller. In short, material and colour selection can promote or adversely affect the performance of thermal mass.

Examples for wrong location of thermal mass
Brick veneer wall construction has brick to the exterior, studs to the interior with insulation between the studs. In this scenario, brick can’t act as a thermal mass as it can’t store or release heat to the interior space.  Conversely, double brick walls can absorb heat, but due to the fact that there is no thermal separation to the outside, they act as a thermal bridge and release heat to the exterior which will increase the heating needs in winter.

Heating And Thermal Mass
Split systems and ducted heating are the most common heating systems in Australia – they function by pumping hot air into the room. When fan or ducted heaters are turned on, a room will be warm, however, immediately after they are switched off, it is cold again. This is because they use convective heat which warms the air, not the materials in the room. Open fire, gas or hydronic heaters eject radiant heat from their hot surfaces. It takes longer to warm a room as it also warms up the objects and materials, the occupants in turn feel more comfortable, as the Mean Radiant Temperature is well balanced. Even when the heaters are turned off, the thermal mass will release its stored heat slowly and therefore keep the room warm for a longer time, depending on the performance of the insulation.

How Thermal Mass is Used Overseas
In most European countries, thermal mass is used as a matter of course. Although it takes a longer to heat up a house which contains a lot of thermal mass, it also takes a long time to cool down again. The thermal mass releases constant heat to the rooms and therefore heaters only need to be on a low setting or turned off completely. Unlike in Australia, split systems and ducted heating are rarely used overseas as they use convective heat. The main focus lies on radiant heaters as they heat thermal mass.
If thermal mass is combined with effective insulation and has good solar access, the interior is perceived to be comfortable, without the need for additional heating, even if the external temperature is well below 20°C. The combination of thermal mass and well performing insulation is a condition of passive solar design, as well as low and zero-energy housing.

Conclusion
Thermal mass is an effective way to reduce the need for mechanical heating and cooling and to increase the comfort and well-being of the occupants. In order to perform at its best, it needs to be located appropriately and sized adequately, with a careful eye on insulation and thermal bridges.

Sustainable Design Features 101

HAIG55-WATER TANK1-LOW RES

Nowadays everyone claims to design sustainable buildings and offer green design solutions. But what does it actually mean?  Is a so-called sustainable home automatically environmentally friendly?  How do you distinguish between real sustainable design and one that claims to be?

The following article is an introduction to a step-by-step series that brings together all the elements that make up sustainable design into one simple overview.

Sustainability

The word first appeared in the Brundland Report (1987). Sustainability is defined as “a concept which deals with mankind’s impact, through development, on the environment. Sustainable Development is “development which meets the needs of the present without compromising the ability of future generations to meet their own needs.” Today’s environmental problems, like air pollution, are largely a consequence of the unsustainable consumption of natural resources and the mismanagement of waste products. Sustainability is about environmental protection, sustained economic growth and social equity”.

Sustainability and Gruen Eco Design

We at Gruen Eco Design are passionate about sustainable design and committed to finding the best solutions for our clients and the environment. We believe sustainable design can and must be affordable and as a matter of course should be integrated naturally throughout the whole design process, rather than designing something and trying to make it sustainable later.  My name is Simone Schenkel and I’m a designer and sustainability consultant at Gruen Eco Design. Thanks to my architectural studies in Germany, an essential part of my education was based on sustainability as well as passive house design. Due to its strict regulations and building requirements, Germany was able to achieve its Kyoto targets three years early and is currently the “world’s leader in climate protection”. I trust that, as Australians we will adopt stricter requirements, as we all play our part in saving energy and protecting our environment. In the meantime I see it as my mission to talk about sustainability and how to save energy passively as well as actively.

The basics of sustainable design

Passive Solar Design aims to maintain interior thermal comfort and to reduce the need of mechanical heating or cooling by allowing the structure of the home itself to collect, store and redistribute heat.

It’s important to note that all sites are different and that there will never be a final or the best design solution. However, there are common features and approaches that need to be applied to every job and it doesn’t matter if you build a townhouse in Melbourne or an apartment block in Alaska. Things like:

  • Optimal House Siting
  • Good Solar Access
  • Thermal Comfort
  • Adequate Insulation
  • Good Windows
  • Thermal Mass
  • Minimising Thermal Bridges + Air Leakage
  • Specifying Sustainable Materials

Each of the above points is important for the energy efficiency of a building. Yet they all need to work together, if one of the elements is misapplied it can jeopardize the performance of a building.

Here is a brief description of the most important things you have to consider when thinking about sustainable architecture.

House Siting  and Solar Access

The siting and orientation of a building is essential to achieve good solar access and hence good energy efficiency. The house needs to be designed according to the site and must respond to specific site conditions to maximize free solar energy. Moreover, it’s important how the rooms are arranged; the right zoning can significantly help save energy otherwise needed for heating and cooling.

More details about how to locate a house on the site and solar access are coming soon.

Thermal Comfort

Why are some houses always uncomfortable and freezing even when the heater is on? Human thermal comfort describes the state of mind that expresses satisfaction with the surrounding environment and refers to several conditions in which the majority of people feel comfortable. Thermal comfort is affected by a range of factors such as convection, conduction, radiation and evaporative heat loss, so even if a heater is on, cold air coming from the window will leave an uncomfortable sensation.

More details about thermal comfort and why it is so important are coming soon.

 

Adequate Insulation

Thermal insulation is a fundamental factor to achieve thermal comfort for occupants. Insulation reduces undesirable heat loss or gain and can lower the energy demand of heating and cooling systems. The ability of insulation is evaluated by its R-value. Nevertheless, an R-value does not consider the quality of the construction, the application of the insulation or local environmental factors for a building. The building codes specify requirements for every climate zone, but keep in mind these are bare minimums only and not best practice.

More details about insulation and which insulation you should chose for your project are coming soon.

Good Windows

Is double glazing worth its money? The answer is YES, but ONLY if it is installed correctly without a cold bridge (thermal bridge). A window or a door is essentially a hole in the wall and responsible for most of the unwanted heat loss or gain.

More details about windows and what makes windows energy efficient is coming soon.

Thermal Mass

Thermal mass is the capacity of an object to store heat. It is an effective way to improve thermal comfort in a building, since it will absorb heat when the surroundings are hotter than the mass, and give heat back when the surroundings are cooler. When situated well and in combination with passive solar design, thermal mass can play an essential role in saving energy and be used actively for heating and cooling.

More details about thermal mass and how you should install it are coming soon.

Minimising Thermal Bridges and Air Leakage

Ventilation is the process of “changing” or replacing air to regulate temperature and moisture control amongst other things. By applying the right design features, natural ventilation and cross ventilation can be used to control indoor temperature and therefore reduce the energy bill significantly. For these reasons, controlling the air movement is essential. Thermal bridges and air leakages will increase the need of supplementary mechanical cooling and heating.

More on how to avoid thermal bridges and air leakage are coming soon.

Specifying Sustainable Materials

What makes a material environmentally friendly and what makes it green? Choosing materials for a building requires careful consideration of products and materials that have a reduced impact not just on the environment but also on the health of the occupants.  Origin, manufacturing process and the life cycle of a product are just some of the properties that play a decisive role in the selection of materials.

More details about which materials you should use for your building are coming soon.