Friday, April 30, 2010



Orientation and layout

The most important aspect of energy–efficient design is the orientation of the home. The home ideally should be oriented so the living areas are facing north to take advantage of the winter sun, with eaves to shade out the summer sun. Bedrooms should be located on the southern side of the home to keep sleeping areas cool, and infrequently used rooms (such as the garage and laundry) are best located on the western side which is exposed to heat in the afternoon.


Ceiling and wall insulation is the single most effective item you can add to your home to improve its energy efficiency. Insulation helps to:

* increase comfort levels by keeping your home warmer in winter and cooler in summer
* reduce the amount of energy required to heat and cool your home, which saves you money on your
* heating and cooling bills and reduces the home’s greenhouse gas emission.

The effectiveness of insulation is rated using the thermal resistance value, or R–value. The higher the R–value, the more effective the product is at reducing heat flow into or out of a home. The thermal resistance value of insulation of your home's constructions will depend on location of your home.
Depending on the home’s design, insulation may trap heat in summer. Homes should be evaluated by a professional insulation installer to ensure:

* windows are adequately shaded
* high windows and skylight vents are able to open
* roof vents are operating.

Shop around and source quotes from reputable suppliers before making a decision regarding insulation.
When choosing insulation, consider using a product that reduces noise. This will help to block out traffic noise, neighborhood noise and noise transmission between rooms.

Consider using lighter colored materials and paints for the roof and exterior walls, as a dark exterior will increase the temperature in the home and decrease the usefulness of your insulation.More info at SOLAR SERDAR.

Heating and cooling

High ceilings provide for improved ventilation and the safe use of ceiling fans. Fans are a more energy–efficient form of cooling than air conditioners – the average air conditioner uses more energy than 12 ceiling fans. Before installing air conditioning, consider:

* have living areas been located near usable outdoor areas to enlarge useful space and encourage breezes?
* is there an opportunity to ventilate the home using breeze ways above doors and in door panels?
* is the home fitted with ceiling fans?

Wood-burning heaters and fireplaces cause indoor and outdoor air pollution and can attract fines if they cause a neighborhood smoke or odor nuisance. Wood–burning heaters are not recommended. If you like the look of wood heaters, consider a gas imitation heater or fireplace.

* If you have decided to install an air conditioning system, is it an energy-efficient model such as a reverse–cycle inverter system that can be used for winter heating?
* Is the air conditioning unit located away from neighbors to avoid causing a neighborhood noise nuisance?
* Is the thermostat set to ideal summer temperatures of between 25°C and 27°C and winter thermostat temperatures of 18°C to 20°C? For each extra degree of heating or cooling, energy consumption increases by about 5% to 10%.More info at SOLAR SERDAR.

Cross ventilation and roof ventilation

Allowing breezes to flow through your house is also an important way of keeping your home cool. Windows should be placed and designed to capture the prevailing breezes. Try to keep short, direct paths between windows. Choose windows with large open areas, such as louvres, casement, sliding or double-hung windows.

Roof ventilation is also important for allowing heat to escape from the roof in summer. Static or moving vents (eg. whirlybirds) can be installed for ventilation. If possible, roof vents should be closed in winter to stop the escape of heat from the roof space.

Windows and shading

The size and placement of windows is a very important consideration when designing your home. Windows can let in too much heat in summer and also allow significant heat loss in winter.

* North-facing windows can be large, but need to have wide eaves for shading in summer when the sun is higher in the sky.
* West-facing windows should be minimised to reduce summer heating.
* East-facing windows can provide early morning sun in winter, but can over heat the home in summer if not properly protected.
* South–facing windows receive no direct sun. Large south facing windows will allow heat loss in winter.

There are various options for improving insulation properties of windows.

* Shading with wide eaves or external shade fixtures is the most effective way to stop heat transfer through windows.
* Internal shade fixtures such as blinds or curtains are not as effective as external fixtures.
* Special glass types and window film treatments allow light to pass through the window but minimize the heat transfer. This may be more expensive than shading options, but may provide a good solution where external shading is not appropriate.
* Double-glazed windows (windows made with two sheets of glass with an air space between them) are a more expensive option for insulation, however they offer the best insulation properties.

Double–glazed windows have excellent noise reduction properties. Closed, double–glazed windows may improve the livability of any rooms that are exposed to excessive outdoor noise.

The energy efficiency of windows is rated using the Window Energy Rating Scheme (WERS). Under this scheme, the window’s cooling and heating performance is rated separately on a scale of 0 to 5 stars – the more stars, the better.


Thursday, April 29, 2010


Solar absorber layers for collectors on the test stand

Since the beginning of 2008 the Thermal materials group has provided the ISFH together with its collector testing station certified by the DIN CERTCO GmbH, with the ability to test the quality of selective absorber layers in respect of their durability during ageing.

Selective layers absorb about 95% of the energy in the sun’s spectral range up to 2500 nm. In the wavelength range above 2500 nm, however, they largely reflect irradiance (Fig. 49). This characteristic leads to the absorber only suffering slight losses during heating due to thermal irradiation. Solar absorption should be as high as possible, thermal emissions as low as possible and they should preferably remain unchanged for the collector’s lifetime of 25 years. Optical parameters calculated from the reflection spectrum therefore form the evaluation criteria for all reliability tests for solar absorbers. These are also supplemented by tests of the bonding strength of these layers.

In 1994 three European research establishments developed accelerated ageing tests for single-glazed flat collectors in the ‘Task 10, Solar Heating and Cooling’ programme. In 2004 they modified the temperature endurance test in the Task-10-procedure because the advent of high-quality absorber layers created with PE-CVD and PVD techniques as well as the use of anti-reflection coatings for collector glass covers had led to higher temperatures and therefore greater stress on the materials. The ISFH provides not only the so-called Task 10 test in its latest version, but also makes use of chemical reliability tests for newly-developed products in order to ensure their suitability for particular environmental conditions.

In addition to this minimum requirement for a practically applicable absorber for flat collectors, the question of the continued reliability of the coating with age again arises for newly-developed collectors or – in an age of global marketing – for use in areas with particular climatic and environmental problems. Collectors in coastal locations are prone to greater problems with salts, while those near conurbations may be prone to increased levels of nitrogen oxides and sulphur oxides. For unglazed façade collectors, these demands on the materials can be particularly high due to humidity and spray. The development of double-glazed collectors as well as the trend towards solar-assisted heating and therefore larger-scale solar installations will further increase the demands on materials, especially as stagnation occurs more frequently and more severely than the current Task 10 test could take into account. Stagnation is the name given to the situation frequently occurring in summer when the solar energy generated by intense irradiance is not used and therefore the absorber area is subjected to temperatures of up to 230°C following the evaporation of the cooling fluid.More info at SOLAR SERDAR.

In order to be able to provide suitable tests for selective coatings and new collector concepts, chemical endurance tests have been introduced at ISFH going beyond the conventional temperature and condensation endurance test (Task 10). Our aim was both to be able in the testing procedure to depict chemical pressures of various types and to be able to meet the industry’s justified demand for an economical testing procedure which could be converted into a norm. We therefore followed the normative testing procedure used in the construction industry for corrosion prevention and testing coated glass and modified this in such a way as to be able economically to carry out the salt spray test in accordance with DIN 50021, the acid spray test in accordance with DIN 50021SS and SO2 and NOx endurance tests with condensing humidity – in a form equivalent to EN 1096-2 – in one piece of equipment (Fig. 50 and Fig. 51).

The ability to perform SO2 and NOx endurance tests in a humid atmosphere using a spray chamber is based on the fact that these gases dissolve very quickly in water as sulfurous or nitrous acids and are oxidized with the ambient oxygen to form sulfuric or nitric acid. Instead of using climate simulators with costly gas injection and safety equipment, we spray the acids at a concentration equivalent to the quantities of gases in the norm.

The test methods have been used for a project supported by the Arbeitsgemeinschaft industrieller Forschung (AiF), in which the Fraunhofer Institutes for Electron Beam and Plasma Technology (FEP), for Surface Engineering and Thin Films (IST) and BlueTec GmbH & Co KG have developed corrosion protection layers for blue absorbers. Extensive tests have proved that the protective layers markedly improve the corrosion resistance of blue absorber layers even in extremely adverse conditions (Fig. 52 and Fig. 53). However, the classic Task 10 test is passed irrespective of the protective coating and, in contrast to our corrosion test, it cannot highlight the difference in quality.


Tuesday, April 27, 2010


Key Elements of a Passive House

From what I can find, there seem to be four main aspects to the average Passive House although each one will vary slightly. I have included two things we all like below before going into further detail – a numbered list and a lovely diagram:

1. Super Insulation that is airtight and minimizes thermal bridging
2. Highly Efficient Windows
3. Mechanical Ventilation with Heat Recovery
4. Innovative & Efficient Heating Technology

Passive House Diagram
Super Insulation

There are a few key elements of super insulating a passive house:

* High R-Value or Low Thermal Heat Loss Coefficient – For the climate in central Europe which is a tad colder than the northeast US here, they will achieve R-Values of 38 – 52 on all external walls, slab foundation and roofs. This level of insulation reduces the heat lost during the winter and the heat gained during the summer to extremely low levels. It then becomes very easy to keep the home at a comfortable temperature with very little energy. Surfaces in the home will also remain at a constant temperature and enable the home to be kept within safe humidity levels for occupants, furnishings and electronics.
* Construction Reducing Thermal Bridging – Heat will flow through the path of least resistance such as wood, metal or certain foundation materials. Therefore it is important to not only have high insulation values, but to eliminate thermal bridges from the inside of the home to the exterior that are common in typical construction. Thermal bridging will waste the time and money spent on extra insulation if left unchecked.
* Airtight Construction – Building an airtight thermal envelope is important for energy savings, humidity control and ensuring the longevity of the building structure. Gaps in the building envelope will allow moisture to seep in, raising humidity to unsafe levels in the home and damaging the structure of the home over time.

High Efficiency Windows

Windows in a Passive House must be extremely efficient as well to complement the super insulation. In Europe they seek an R-Value of just over 7 which is no easy feat. They use triple pane windows with low-e coatings and Argon gas to reach this goal. They also seek a low U-value of less than 0.20 where a very good Energy Star window in the US will be closer to the 0.30 mark. Below are the three main requirements of windows for a Passive House according to the Germans:

* Triple glazing with two low-e coatings
* “Warm Edge” spacers between the panes of glass
* Super-insulated frames

Mechanical Ventilation with Heat Recovery

Proper ventilation of a Passive House is critical especially due to the air tightness in the home that does not exchange the stale air with fresh outdoor air very much at all. Opening the windows is not a convenient strategy, nor one that can be performed year round. For these reasons a mechanical ventilation system in the form of an HRV or ERV is used to exchange stale air from the most polluted rooms (kitchen, bath, utility) and fresh air is vented into the living quarters (living room & bedrooms).More info at

A Heat Recovery Ventilator (HRV) or Energy Recover Ventilator (ERV) is used in order to recover 75% to 95% of the heat by passing the warm exhaust air past the incoming cold air in a method that does not mix the two streams in order to make sure only fresh air is being vented into the home and no air is being recirculated.
Innovative & Efficient Heating Technology

The heating requirement is so low in a Passive Home due to all of the other factors that usually the home can be heated by simply heating the fresh air that is being brought into the home via the mechanical ventilation system. Various methods can be used to heat the incoming air inline which eliminates the need for additional ducting in the home. Some of the common methods to heat the air in a Passive House include the following:

* Small heat pump
* Small condensing gas burner
* Small combustion unit for biomass fuel
* Compact unit for all in one heating, ventilation and domestic hot water

Finally we’ll end with one of the charts I found from a case study (linked below) on a passive house built in Europe. It shows the effect on the heat requirements of a typical new home in Germany that each measure implemented has on the home.


Saturday, April 24, 2010



Our comprehensive range of advanced condensing boilers for retrofit installations and new homes deliver up to 35% energy savings. In combination with intelligent controls an additional 10% energy savings is achievable.
Heat pumps

In addition to a complete range of electric heat pumps we are developing gas absorption heat pumps. Heat pumps transfer energy from the environment at zero cost and with zero emissions, resulting in up to 55% energy and CO2 savings.
Micro co-generation systems (CHP)

At the forefront of our R&D activities are micro co-generation systems using solid oxide fuel cells or Stirling engines. They produce electric energy and heat at the same time in the exact locations where they are needed.

Friday, April 23, 2010


Dear Homeowner,

Are you tired of paying $200 or more for electricity? Do you hate your electric bill? With a solar home, you can reduce your electric bill without turning off your air conditioning and suffering through the hot summer months.
A SOLAR SERDAR residential solar power system produces free, clean, renewable energy. As a utility customer, you may qualify for a rebate. And with the eight year extension of the 30% Solar Investment Tax Credit (ITC), you may also qualify to have the government pay you $20,000 or more for installing a medium-sized solar panel system on your home.

Last year our clients enjoyed record low electric bills, as low as $29.50, $0 and even -$67 (you read correctly, the electric company owes them money!). Some received an astonishing $100,000 from the government for their solar panel installation.

Thursday, April 22, 2010


Introduction to ecological heating and ventilation

This section presents various systems, which may be used for the heating and ventilation of an ecological house. Some systems can be used successfully in regular older houses as well; in particular the systems for “green” domestic water heating and ventilation, which could be installed in virtually any older building. We distinguish between space heating, i.e. heating of the rooms in the house, and tap-water heating, i.e. domestic hot water. (Solar collectors should heat the tap water in any house).More info at SOLAR SERDAR.

All houses need ventilation. In a super-insulated passive house, a ventilation system with heatrecovery is nessesary, as well as some means of heating tap water. We consider good ventilation essential in any type of house, however, it is difficult to achieve good energy performance without some form of reduction of the ventilation heat losses. This is why we recommend a minimum of three systems in any type of house:

* Ventilation with heat-recovery
* Space-heating
* Tap-water heating

Reduce the heat losses first. Please keep in mind that the amount of energy needed should be reduced as far as possible in the construction of the house. Secondly, the location and orientation of the house and the amount of hot-water usage will dictate which system to choose. The initial investment cost, the life-length and the complexity of the system must be considered both for economical reasons but also for ecological reasons.

KISS (keep it simple). Ideally the inhabitants of the house should be able to understand and maintain the system - otherwise it might not work at all - and that would not be very ecological!

Air-air heat pumps. For some strange reason these economical heat pumps are practically unheard of in Ireland and Britain. They give off 3-5 times the amount of energy used and they are cheap and quick to install. One drawback is that they only heat a local area, much the same as a stove. Works best with open plan.

Geothermal heatpumps. We are not covering the large type of heat-pump that connects to pipes in the ground. The electrical power consumption of such a geothermal heatpump is usually 2-3kW with an output of 6-12kW. We consider that to be oversized for most low-energy and all passive houses.

Wood pellets and wood chips. On these pages we are not covering this type of environmentally sound source of heat. The reason is that there is an abundance of information about wood-pellets, wood-chips and pellet-boilers from many other sources.

Wednesday, April 21, 2010


How to prevent water damaging buildings and health

The term ‘breathability’ is becoming ever more widespread and, although a useful concept, it’s often misunderstood. It sounds as if it is about air but in the context of building performance it’s about water. Breathability describes how a structure reacts to water as a liquid or vapour, primarily through:

* Vapour permeability (how materials allow water vapour to pass through)
* Hygroscopicity (how materials absorb/release water vapour)
* Capillarity (the transmission of liquid water)

Breathability should be central to the design and renovation processes. It affects the health of the building and the occupants, especially as we try to improve the thermal performance of our homes. It also effects the environment, as the materials that provide the best breathability are often the natural, more traditional ones, although only recently have we begun to understand why.More info at SOLAR SERDAR.

An estimated 75% of building failures are due to water - either rainwater penetration, interstitial condensation or inner surface condensation. This starts with the outside of the building where vapour closed finishes (such as hard cement renders or high resin paints) can cause considerable damage by trapping moisture. It’s possible, often desirable, to have a capillary closed external finish but it should usually be vapour open. Research into modern timber frame constructions shows that drying is more effective through vapour open materials than through “vented” cavities, which often have no air movement.

Moisture effects performance. If the moisture in mineral wool increases by 1 or 2% its thermal resistance halves. Water molecules effectively form a cold ‘bridge’ and fill up the insulating air voids. Insulation gets wet in a number of ways and with non-breathing materials it takes a significant period to dry out, resulting in longterm loss of thermal resistance and allowing moulds the opportunity to develop. Completely water impermeable materials are not effective either, as the moisture content of walls can increase or remain damp, lowering thermal resistance.

It is Irish practice to use non-breathable materials and vapour closed designs in standard timber frame constructions. While this works in theory, if the timber or insulation gets wet while building or if vapour barriers are ‘punctured’ by alterations, water will be trapped, the timber can start to decay and moulds can develop. In breathable structures the moisture is drawn harmlessly outwards. As German regulations make clear, no timber treatment is necessary in timber frames with breathable construction. Only vapour closed constructions require preservative chemicals. Similarly in roofs, rot can result with vapour closed constructions or vapour resistant insulation. If the roof gets wet in construction or the vapour barrier is breached, as it usually is, the timber will collect water as it is the only vapour permeable and hygroscopic material present (it may retain it for a significant time).

The standard methods of internal wall insulation (battening out plus a vapour barrier behind plasterboard) can also lead to problems. Joists and floor junctions are in the most danger as moisture can collect here, so rising damp and even structural failure can occur. If a vapour permeable hygroscopic woodfibre board is used, these problems are usually avoided.

Breathable paints and plasters can be used internally to halt surface condensation as they absorb and disperse water droplets. This is especially helpful in renovated buildings, where installing ventilation is difficult.

Consequently, a knowledge and use of breathable materials will ensure that buildings have a good thermal performance, and are safe from moulds and rot.

In improving energy efficiency, we strive to make buildings more airtight. This affects indoor air quality, which affects human health. Large amounts of trapped moisture have been directly linked to allergic reactions (particularly asthma) and other autoimmune diseases, as both moulds and dust mites thrive in high humidity conditions. We should pay particular attention to this in the UK and Ireland, which has the largest incidence of asthma worldwide. Low humidities also have an adverse effect, as certain bacteria can flourish and mucous membranes become dried and vulnerable to dust and toxins. A healthy environment has a relative humidity of between 40 and 60%. This is also the most comfortable.

Current solutions use mechanical ventilation to maintain humidity. Many people feel that this is not enough and that we need the design and materials of the building to control moisture as well. This would stop us relying on ‘external’ systems, which need maintenance, repair and have a limited life. Achieving a healthy, robust and breathable building is not difficult. It involves simple safe designs and fully breathable materials which are already in common use across much of the continent and in historic buildings world-wide. Natural materials and systems have a proven track record and are also best from an embodied energy and resource view point.

For the health of both our buildings and ourselves, a proper understanding of breathability is essential. Only in this way can we improve energy efficiency, reduce building failure, and attack the root causes of many health problems. And, as an added bonus, it’s good for the environment too!


Tuesday, April 20, 2010


Passive House Retrofit

Improving the overall efficiency of a nation's housing stock by insisting new buildings reach the impressive passive house standard can mean a 90% energy saving and a high level of thermal
comfort. Serdar Željko from SOLAR SERDAR explains how it also makes
for an increasing role for renewables in the built environment.

In many central European countries energy consumption for heating and domestic hot water causes around one third of national CO2 emissions. For this reason the reduction of energy demand from
buildings plays an important role in efforts to control anthropogenic
greenhouse gas emissions.

As measurements in several hundred different types of accommodation show, energy consumption in new houses can be reduced drastically. For instance, while a typical new single family house in
Austria has an specific space heat demand of 75 kWh/m2 of treated floor
area (TFA), the demand of a so called ‘passive house’ is 15 kWh/m2TFA or

Furthermore, in recent years the market share of new passive houses in Austria has grown significally. More than 2000 passive houses have been erected in the last decade. In Vienna, large
settlements are to be developed to passive house standard, and in the
region of Vorarlberg in western Austria, social housing companies have
been obliged to build to passive house standard since 2007. More
recently, a broader spread of building types has been realized in
passive house-standard, including office buildings, schools,
kindergartens, super-markets and others. Both the German and Swiss
markets are seeing similar developments too, and while passive house was
a standard mainly limited to the German-speaking countries initially,
the past five years have seen it begin to spread across Europe. This was
partly due to European research and development (R&D) projects such
as the Promotion of European Passive houses (PEP) programme or the
Passive On programme.

Today, ‘passive house’ is a clearly defined standard across most of Europe for buildings of a very high energetic performance. Experience has shown that a single definition of the
passive house can be used at least from 40°–60° latitude, and passive
house definition has been tested in both Scandinavia and southern
Europe. Key parameters are a specific space heat demand maximum of 15
kWh/m2 TFA, a specific primary energy demand for space heating, cooling,
domestic hot water, electricity for pumps and ventilation and household
appliances at a maximum of 120 kWh/m2 TFA, a maximum heat load of 10
W/m2 TFA, and an airtightness of n50 0.6/h maximum.

Retrofitting passive house components

Although the successful implementation of passive houses in new buildings plays an important role in the overall strategy to reduce greenhouse gas
emissions, the improvement of the energetic quality of the existing
building stock is of even bigger importance. In Austria, the yearly rate
of new built apartments is about 1% of the existing building stock.
Depending on age and building type, the specific space heat demand is
130–280 kWh/m2. As only about 1%–1.5% of the building stock is
retrofitted per year and this rate cannot be increased to much more than
2.5%, the improvement of the energetic quality of retrofits is
essential in order to reach the national, European and international
targets for the reduction of greenhouse gases.

However, since 2001, more and more renovations in Austria, Germany and Switzerland have been carried out using components that had previously been tested in new passive houses. Different names
are used for these houses, sometimes called ‘factor 10-houses’ as the
energy demand after renovation is only a tenth of the original demand.

In these projects, a specific heat demand after renovation of 15 kWh/m2 TFA, was achieved.

The main elements of the energy concept are typical passive house components:

* Excellent insulation level of opaque building elements: u-values range from 0.10 W/m2K for walls and roof to 0.18 W/m2K for basement ceilings.
* Triple glazed windows with adequate frames and an optimized installation.
* Thermal bridges reduced to a minimum.
* The airtightness was improved by a factor of 6–10, the limiting value for new passive houses was achieved.
* A ventilation system with highly efficient heat recovery installed.
* Thermal solar collectors installed covering up 60% of the annual energy demand for domestic hot water.
* Highly efficient condensing gas boilers were installed; where possible, ducts have been insulated to a very good level; in other projects biomass boilers have been successfully tested.

Benefits of the retrofit programme

Experience with the renovations up to passive house standard is so far very good in the Vorarlberg projects, as well as in projects in other regions of Austria, Germany and Switzerland.

Thermal comfort has been improved to a level superior to that of a conventional new house; due to the ventilation system the air quality is improved, and energy bills are reduced drastically. As
thermal bridges are minimized, the airtightness is significantly
improved and the air exchange is always up to hygienic standards due to
the ventilation system; the main causes for structural damage and mould
problems are also eliminated.

Furthermore, the measured energy consumption shows good congruence to the demand that was calculated in advance using the passive house planning package (PHPP).

Austrian and German research has shown that for bigger apartment buildings renovations to passive house standard or very close to it cost about E450–600/m2 TFA. The extra cost compared to a
renovation up to national building code is in the range E80–150/m2 TFA.

For comparison a new apartment building costs about E1600/m2 TFA in western Austria.

Nontheless, detailed analyses show that most of the measures used in passive house retrofit are economically feasible, for example, the overall lifecycle cost for investment and energy is lower
using the passive house insulation of 26 cm compared to the building
code insulation of 12 cm. As for most renovations lifecycle costs are
not calculated, home owners and housing companies tend to realize
suboptimal insulation thicknesses, for example.More info at SOLAR SERDAR.

In some regions of Austria, the regional funding system therefore differenciates the rate of funding according to the energetic quality of the house after renovation – the lower the energy
demand, the higher the funding. The experience in Austria, with nine
different funding systems in its nine regions, shows that this funding
rate differenciation is an effective way of encouraging very high
quality standards.

Rolling out retrofitting tools

After demonstrating the technical and economic feasibility of renovations with passive house components in several R&D projects, the next step is to establish high quality renovations
as a standard in all European countries.

The e-retrofit tool project, co-financed by the EC’s Intelligent Energy Europe programme, aims to inform social housing companies across Europe of the principles, advantages and technical
approaches of high quality renovations. Six institutions from five
countries are involved in the project, including the Faellesbo social
housing company and COWI A/S, both of Denmark, the Energieinstitut
Vorarlberg research institute of Austria, the ECN Energy Research Centre
of the Netherlands, Asociación de Investigación Industrial de
Andalucia, of Spain, and Lithuania’s Housing Agency.

The main element of the project is an internet-based tool giving basic information to social housing companies that enables them to find out whether they have apartment buildings in their building
stock that are suitable for high quality renovation. Social housing
groups have, in particular, been selected as a target group as they are
frequently responsible for a very high number of large, identical

Initially, a common definition of ‘passive house renovation’ or ‘high quality renovation’ is required. After a detailed analysis, the following definition was found: ‘A passive house retrofit
(PHR) is a renovation that improves the specific demand for heating, and
cooling in southern countries to a maximum of 30 kWh/m2 TFA.’

The calculation of the demand is made using the passive house planning package (PHPP). In a second step, a maximum value for the overall primary energy demand shall be added to this
definition, the value of 30 kWh/m2 TFA was fixed. This value was chosen
as in some cases it was shown to be prohivitively expensive to reach 15
kWh/m2 TFA. Even so, many of the projects realised so far have aimed at a
specific heating demand of about 25 kWh/m2 TFA.More info at SOLAR SERDAR.

For the internet tool, a structure that combines common information for all European countries with country-specific information was developed. Common parts of the tool are an explanation
of the different energy standards for passive house and passive house
retrofit, a description of the principles of passive house retrofit, its
advantages, and about 35 measures feasible under a passive house
retrofit programme.

While these measures may differ from country to country due to climatic differences or differences in construction traditions, the main elements are identical.

In a second part of the tool, the implementation of passive house retrofit is demonstrated in building typologies for each of the countries involved in the projects.

For each country, between three and nine building types typical to the building stock of social housing companies were identified, and for each type calculations made to find out the most
promising approach to reaching the energetic aim of a maximum of 30
kWh/m2 TFA. In most cases, buildings of different ages were analysed and
calculations made using PHPP togther with regional weather data. For
each building type, a proposal for a passive house retrofit (PHR) is
given, the measures selected from the list of 35 measures are specified,
the specific energy demand for space heating and cooling calculated for
three standards: actual state, after renovation according to national
building standard, and after PHR. From these figures, the final energy
demand for heating, cooling, ventilation and pumps is calculated, as
well as the energy costs.

In another table, the energy demands for incomplete passive house retrofits are specified, showing the impact of individual measures on energy demand.

Topics, including costs and economic feasibility, are described in separate chapters. Best practices from 10 European countries are also integrated into the tool, which, in addition to the
five participating countries, has been transposed into nine more
national versions of the tool. For these countries, such as Croatia, Italy,
France, Portugal, Slovenia, and the Czech Republic among others, the
building typologies of the participating countries were used.

Following testing and optimization with social housing companies, architects and engineers, as a final step of the project development, 60 social housing companies in more than 10
European countries were approached and guidance was given at three
levels from initial guidance to sketch proposals for some of the

The social housing companies showed great interest in both the tool and in the concept of passive house retrofit. In many cases, the integration of a ventilation system into an existing building
was the measure that needed most explanation.

For those countries with no experience in passive house retrofit it would be initially helpful to develop research projects with a detailed planning, an analysis of costs, extra costs and
economic feasibility. These projects may be used to define the most
efficient funding systems and, as the experiences in the implementation
of new passive houses show, the further education of architects,
engineers and craftsmen is an important accompanying measure for


Monday, April 19, 2010


1. When calculating the heatloss through insulation the Density of the insulation is as important as the U-value . The best insulating materials have a good U-value and density like Softboard, Cellulose, Poroton and heavy Rockwool.
2. When Cold wind blows directly onto insulation the Cold jumps through lightweight insulation a lot quicker than Dense insulation reducing the U-value and the effect of the insulation. This is called the "Wind Chill" factor.
3. When Swedish builders put 3 x 10cm layers of insulation in an attic floor they always put a layer of building paper between each layer of insulation. This improves the effect of the insulation by 60% because it stabilises the trapped insulating air in the insulation and stops the wind blowing it away.
4. Lightweight insulation like the stuff insulating most caravans allows the caravan to heat up like an oven an hour after the sun comes out, this is known as the "Caravan Effect". Dense insulation like the stuff around your dishwasher holds in heat for up to 12 hours.
5. If the moisture level in your insulation increases by 10% the U-value is reduced by 30%, so natural hydroscopic insulation that can dry itself out like Cellulose, Sheepswool, Hemp etc,. works much better in the long-term by allowing your timbers to breath/sweat and by maintaining the U-value of the insulation.
6. A lot of air that should be trapped in your insulation is blown out by external wind so it's important to put a windtight layer of dense breathable insulation outside the soft insulation to maintain the U-value of your insulation.
7. Polyeurethene Insulation (the yellow stuff with the foil on both sides) is not suitable for use under concrete floors because it loses its U-value when it gets wet. When you put plastic on both sides of this insulation to prevent it getting wet you trap condensation between the plastic layers making and keeping the insulation wet. In the middle of every floor and wall you have a "Dew Point" or Condensation point and you are not suppose to put plastic foil on the Cold side of insulation because it traps moisture. If you leave out the top layer of plastic, which is often the case, the Aluminium foil dissapears due to a chemical reaction between the foil and the cement allowing water into the insulation which messes up the U-value. Better to use water proof Polysterene for your foundations.
8. The effect of rigid insulation sheets in a cavity wall is reduced by between 35% and 197% due to "Thermal Looping" which is the unavoidable airflow between the insulation and the wall. With a 5mm airgap the U-value is reduced by 35% and with a 10mm gap the U-value is reduced by 197%. Concrete blocks are made to a tolerance of + or - 2mm so 2 blocks beside each other in a wall can have a 4mm thickness differential. In most walls we see snots of mortar between the blocks keeping the insulation even further away from the inner wall, mortar also falls onto the insulation preventing a tight fit between insulation sheets.
9. 35% of the heatloss from your house is from leakage so Airtightness goes hand and hand with a good insulation job. To achieve good airtightness use a vapour barrier on the warm side of your insulation. OSB board with the joints taped can also be used on the warm side of your insulation as a Vapour barrier and as an Airtightness layer. This prevents warm air from escaping and keeps your insulation dry.
10. 25% of the fabric heatloss from a standard house is lost through "Cold Bridging". These are the uninsulated areas of your house and are mainly around wall/floor junctions, wall/roof junctions and around windows and doors. So "Cold Bridge" elimination is an important exercise when building or renovating your house.
11. Using non breathable rigid sheet insulation in a roof or in a timber frame house is not a good idea because of the 50% rule in Germany which states that structural timbers may not be covered by more than 50% with non breathable materials. In such a structure the only escape route for moisture is through the timbers which quickly become saturated leading to rot. A breathable roof using a combination of Cellulose and Softboard allows the complete roof to breathe and sweat leading to healthy roof timbers and a roof with a long life. Lightweight insulation materials are anyhow not suitable for roofs because of the "Caravan Effect" explained above.
12. The Finnish guy who patented Insulated Concrete Forms over 40 years ago designed a series of air channels in the inside layer of the insulation to help overcome the problem he discovered with fungus/mould growth in the walls when unavoidable water vapour gets into the insulation. The systems that are being erected now in Ireland do not have these air channels in place so the risk of fungus and mould growth in this construction method is quite high. When you put a Tupperware box into your fridge water starts flowing down the inside of the box!
13. An uninsulated wall usually has the Dew Point at the centre and the inner wall face is warmer than the external face. If you dryline you move the Dew Point to where the insulation and the wall meet and the wall now becomes a cold wall. With the new Airtightness regulations there will now be less airchanges so the air is your house will have higher water vapour levels. The joints between insulation backed plasterboard are never sealed and with high air pressure inside the house, water vapour will get in behind the insulated plasterboards and condense on the Cold Wall causing fungus and mould growth. The only way to avoid this is to leave an airflow between the insulation and the drylining. This means that the combination of a partial fill cavity wall with drylining isn't possible as the ventilated cavity behind the drylining messes up the U-values. External Insulation moves the Dew Point to the outside which is much safer.More info on SOLAR SERDAR.
14. Durability: Natural fibres are on the whole much stronger than glass and rock fibres. Much conventional fibre insulation collapses and degrades over a few years (note the loft insulation which is now a damp blob). If buildings are to last over 100 years then we need insulation to last at least as long, particularly in areas where it is difficult to replace or renew. Natural fibres are known to last this long in the correct environments. As regards gas blown insulations, there remains a significant question as to whether these gases will remain for the life of the building. In many peoples opinion only air based insulation is guaranteed. And as regards multi-foil insulation, there are major concerns about the claims made by the manufacturers.
15. Thermal performance with moisture: Natural fibres absorb and desorb moisture hygroscopically, unlike synthetic fibres. Far from reducing their overall thermal resistance this has been shown to improve performance in comparison with conventional materials. In one study comparing flax insulation with mineral wool insulation with a similar designed thermal performance over a bathroom, the thermal resistance of the flax insulation fluctuated more than the mineral wool, but overall had about 10% better resistance.
16. Specific heat capacity : Most natural fibres have a specific heat capacity of about 2000J/kgK, compared with 800J/kgK for mineral wool, and 1400J/kgK for plastic insulations. When combined with the higher density of most natural insulations this means that the thermal mass of natural insulations is considerably higher than conventional insulations for the same thermal resistance. This means that they give far better thermal storage and overheating protection both of which are increasingly important in energy efficiency strategies, particularly in light weight structures.
17. Acoustics: The multi-functionality of natural insulation products extends also to their acoustic performance, which again is far superior to synthetic fibres and plastic insulants, thus making them highly cost effective in designs where thermal resistance, overheating control and acoustic insulation are all required. Add in their breathable qualities and the products become cheap.

Thursday, April 8, 2010


Getting ready for renewables: how to reduce energy consumption at home

Before even considering installing renewable energy technologies at home, you must first reduce the amount of energy you use. But the good news is that this can often be done simply and cheaply ­by making a few minor changes around the house. Read on to find out how …
Turning down domestic heating thermostat

Heating and hot water accounts for around 83% of the total energy used in the home. So team a more efficient boiler with a full set of heating controls and you'll spend less heating your hot water. Photograph: Alamy

It's easy to get bamboozled by technology when it comes to making your home more energy efficient. You want to reduce your carbon footprint but is a wind turbine on your roof the answer? Perhaps solar panels? Or will loft insulation and changing the lightbulbs be enough?

Energy use in homes accounts for over a quarter of the UK's carbon footprint. If you want to reduce your carbon footprint it's important to make sure you are using energy as efficiently as possible. Then you can begin to think about getting your energy from cleaner sources.

Fortunately, the first bit is the easiest and cheapest. Britons top the league in Europe when it comes to wasting energy – largely due to insufficient levels of insulation in the walls and roofs of our homes. All that extra energy use sends millions of tonnes of carbon dioxide (CO2 ) into the atmosphere. But tackling this problem requires no new technology, just modest DIY and some changes in habit.

Loft insulation

First things first, poke your head up into your loft. Is there at least 270mm of insulation up there? Installing loft insulation is by far one of the easiest way to chop your heating bills, saving around £150 a year in an un-insulated loft and can easily be done yourself at an extremely low cost. Alternatively, an installer will typically be able to fit loft insulation in your home for around £200 , with a pay back period of less than two years.

If there is already some insulation up there, then be sure to top it up to 270mm, you could save around £45 a year on your heating bills.

Wall insulation

Insulating cavity walls is also a good idea - a third of a home's heat is lost through walls. Homes built after 1920 are likely to have external walls made with two layers of bricks with a small gap between them. Filling this with insulation will cost a couple of hundred pounds (though you'll need a professional to do it) and pays for itself within two years.

Solid walls (such as those in Victorian houses) are harder to insulate but it is possible by insulating and rendering the outside of the house or building an internal stud wall and filling the gap between that and the brick wall with insulation. It is more expensive but will reward you with a warmer home.

Draught proofing

Turn to your windows and doors next. Draughts can make a room uncomfortable as heat is lost and cold air comes billowing in. Apply inexpensive plastic or foam strips (available from DIY stores) to window and doorframes to stop the winds. If you have the budget, consider replacing single glazing with modern double-glazed units. As well as keeping the heat in, they will also reduce the noise coming in from the outside.

Heating controls and condensing boilers

Heating and hot water accounts for around 83% of the total energy used in the home. So team a more efficient boiler with a full set of heating controls and you'll spend less heating your hot water. A new A rated gas condensing boiler and heating controls could save you around £235 a year.

A full set of heating controls including a time switch/programmer, room thermostat, hot water tank thermostat (if applicable) and thermostatic radiator valves.

If you already have heating controls make sure you know how to use them, for example setting your heating and hot water to only come on when you need it will cut down on the energy you use. And simply turning your thermostat down by 1oC can cut your heating bills by 10% - saving you around £55 a year.


Lighting is another simple way to cut your energy bills. Energy saving lightbulbs use around a fifth of the energy and last up to 10 times longer than traditional lightbulbs. Each one might save you around £40 in electricity over its lifetime.

When you go out to buy new appliances such as fridges, dishwashers or washing machines, make sure you look for the Energy Saving Recommended logo. It's your guarantee that they are the most energy efficient on the market.