Passive House BlogHi welcome to the passivehouseandhome.com blog page. We are passionate about building low energy sustainable houses and homes and welcome any comments you may have. Jun 21, 2011 Sustainable HousesPassive Houses are the most sustainable type of house.The whole concept of passive building is to bring the construction to levels never seen before in traditional houses. In fact the very idea of building to a passive standard is one where old traditional ways to build are brought to a whole new level. What do people mean by sustainable? Is it a building that is capable of been self sufficient in terms of energy output.In reality it should be energy nuetral. Now an energy nuetral house is a wonderful concept but the reality is that it is a near impossible goal. Ok you might build to a passive standard which nearly eliminates the need for fossil fuels to heat the house and you may get enough solar panels and wind turbines to generate enough electricity to meet your needs. You may use solar power to heat your water but all these additional items cost so much money it makes no sense to install them other than our desire to be self sufficient. So what is sustainable in a house.To me a sustainable house has all the qualities of a passive house with additions such as solar or wind with proper rain harvesting facilities etc. If a house is to be built to a sustainable level it needs to have 1. Passive design 2. Additioal features such as water harvesting. 3. Minimal use of utility services 4. Ability to add bolt on items to reduce energy. The overall concept of the sustainable house is very important as it drives the agruement that independence from utilities is a good thing. We need to understand that reducing dependance on utilities is a project that each house owner can make happen and by investing in energy saving schemes it will lessen the cost of utility bills on a yearly basis. The other question is the cost vis a vie the savings of installing energy reducing measures to our homes. Take water harvesting. If you have a house with with a garden then water harvesting is an ideal long term way of minimising water bills. It is essential to weigh up the benefits against the cost and the increased value a system will give to the house. In my next blog I will set out examlples of the costs of each device against the utility costs and the saving over time as well as the pay back of each device Permalink -- click for full blog post "Sustainable Houses" May 17, 2011 Airtightness and the Passive Home
A leaky house will rob you of about 40% to 60% of your heat. I use the word rob to emphasize the effect leaks have on your homes comfort as well as your pocket. People who think the efficiency of insulation on its own forget that insulation used in a leaky house is more or less useless. So what do we mean by air tightness and how can it be improved.
So what is air leakage.Air leakage is air which is flowing into and out of your house in an uncontrolled manner.You know the story of curtains shaking on a windy night. Draughts under the doors etc. Air tightness is of course the opposite in that it is the controlling of air into and from a house. Modern homes rely on air tightness to minimize heat loss and to increase comfort levels. Of course do not confuse air tightness with ventilation. Ventilation is a planned method of extracting air from the house.
How can we measure the air tightness in a house.Measuring air tightness is usually measured by a door blower.A door blower is just a big fan sealed at the door to give a pressure difference in the house from the outside.The difference in Pa is about 50 and when this difference is reached it is easy to see if and where house is losing air.
In the UK and Ireland the upper limit of air tightness at Q50 is 10m3/hr/m2 of the building envelope.
If you can consider the area of external walls in your house and multiply the area by 10m3 of air every hour you get some idea of the air movement.The above limit is so poor that it can be considered useless.
If you where to install an air exchange the air tightness would need to be less than 3m3/hr/m2 to be effective.
Passive houses look to meet or exceed 0.6m3/hr/m2.
A passive house will be 16.6 times tighter than the standard built.
Of course if you achieve the level of air tightness in a house you have to ventilate the house to ensure that you get no condensation build up etc.
This is achieved by air exchanges using the hot expelled air to heat the new fresh air.
The simple answer is to plan the building and the potential weak spots with care.Use good materials and ensure that the site team understands and buy into the logic of air tightness.
Look for very high standards in terms of results.
Test before finishes to seal up potential problems.
Inspect and sign off before covering up.
Permalink -- click for full blog post "Airtightness and the Passive Home"
The most difficult area to control heat loss through a structure are the building junctions.
By building junctions we mean wall to floors,windows to walls and walls to roofs.
The more you insulate the floors walls or roofs the more heat flows out through the thermal bridges.
It's enough to drive you mad!
I like to think about heat loss as a liquid leaking out of a vessel.
If the vessel is full of holes the liquid just drains away gently.
If you start plugging the holes the liquid flows much faster as it has a smaller escape route.
A thermal bridge acts in much the same way.
Now the use of accredited details will bring the Y value to an acceptable level of 0.04 but in passive houses it needs to be zero.
Of course we can model the junctions with software such as therm but the really cool way would be to make the details simple and idiot proof.
The reason I say this is because the accredited details as good as they are and modelling are dependent on workmanship which is never a good thing in mass production housing sites.
Take for example the window wall junction where we are trying to achieve a zero Y value.It is impossible with a 100mm cavity but many insulation manufacturers still try to peddle the belief that a 100mm cavity can be used by using window insulative surrounds.
Modelling a window with such a cavity by Therm or any other software cannot satisfy the requirements.
Now I have looked at all the insulation window surrounds on the market and I am struck by the lack of innovation in the market place.
It seems to me that the way forward is to use a window surround that is much larger than the present types with the surround encompassing the outer and inner walls.
The other area is the way the window surrounds are made without thought given to the window installation.
If you have a 100mm cavity the surround will become 300mm wide and the thickness will be determined by modelling.The question arises as to fireproofing and plaster cracking at the masonry and surround joint.Can a surround of this size be made to suit a brick facade?
The window wall junction is only one area where the use of prefabricated accessories would take the mystery out of the building process and ensure thermal bridging is eliminated.
All the other junctions can and should follow this logic and a building accessory be designed to eliminate the idea of a thermal bridge.
Until we make such accessories the elimination of thermal bridging will be an aspiration only.
Permalink -- click for full blog post "Thermal Bridging a bane to detailers"
Traditional or Prefabricated Build to meet Passive standards.?
The dilemma for many builders and designers entering into the new and growing passive market is the way the buildings are to be constructed.
Traditional building practices have developed to meet local conditions and are proven but do they cut the mustard in terms of quality control required by a passive building.
On the other hand introducing new products and systems can be appealing but are they suitable to local conditions.
The debacle in British Columbia when new untried and untested building systems were introduced resulting in building failures and huge ongoing problems.
If you are thinking about building green or more precisely building a passive house then you have to think not only about the way you build the house but also if that way will meet the exacting standards passive certification requires.
In many ways the precision of the construction of a passive home ensures that the detailing will not fail regardless of the building technique.
But back to question traditional or prefabricated.
The use of prefabricated systems offer more reliability to the construction process in passive buildings.
The reasons are simple.
Each element be in a wall or roof component can be designed and manufactured in factory conditions.
The critical junctions in the house construction can be designed and installed in a controlled way.
The use of prefabrication reduces human input so workmanship issues reduce.
It is my belief that the future of house construction will be with more prefabricated systems as the demands for houses meeting passive standards increase.
The prefabrication issue will be a hybrid design encompassing traditional elements witch will be prefabricated.
Thus a concrete house construction will use precast forms instead of block work.
Precast concrete has an opportunity to really excel in the passive housing market in terms of air tightness and solar mass.
Timber prefabricated housing is another way of using a traditional material and adapting it to the passive construction system.
Stick building will decrease and perhaps vanish as it will struggle to meet the newer standards required.
The reduction of labor from site activities will be offset in the use of tradesmen in factory settings to prefabricate walls, roofs etc.
There are unresolved problems in passive houses particularly in the area of thermal bridge design and air tightness.
The problem is not with the specifications but rather the ad hoc approach used by different building systems.
In my next blog I will discuss the issues of standardized detailing to meet zero thermal bridging and the products required to meet the challenges.
Permalink -- click for full blog post "Traditional build or Prefabricated build"
Passive Homes Ltd are building experts with over thirty years in house and commercial construction.
Permalink -- click for full blog post "Passive Homes Ltd are building experts"
By using traditional building and green technology house owners can now built passive houses that can be lived in without any need for home heating.
Permalink -- click for full blog post "Passive House and Homes, Green building in action,"
Building Passively using local trades or tradesmen is in many ways a misnomer.The real question is how to ensure that your local trades understand the concept and rational behind the passive way.
The construction of a passive house will test every person involved in the project. Workmanship is key to a successful outcome in most things in life but to build a passive house it is vital that each trade ensures that they meet or exceed the specification.
In building passively the workmanship and adherence to the specification is paramount.
To achieve this level of workmanship the trades must buy in to the concept and must be persuaded to act if the previous trade is deficient.
This type of action is not normal in building houses, as the norm is to get on with it even if the previous trade has being poorly constructed.
Thus if the plumbing is not insulated correctly the tendency was to cover it up with plasterboard etc and the see no evil hear no evil syndrome takes over.
This cannot happen in a passive house and the idea of covering up defective work will act as a disaster to passive certification.
The training to up skill construction workers is in many cases getting them to understand the consequences of poor workmanship and to understand the principle of responsibility for each others trades.
Most tradesmen will prosper in the passive house era as only the best will survive and any cowboy or lazy tradesman will fall by the wayside.
Buying a second hand house can be stressful. On one hand the property seems fine but looks can be deceiving.
Most countries insist that a second hand house gives an energy rating to the prospective buyer in order to ensure they know the energy performance of the house.
The problem with energy certificates for second hand homes is that a lot of the areas which are closed to the surveyor or assessor are the areas where insulation is placed and the performance rating is basically a guesstimate.
So this is what a savvy buyer should ask for before they commit to buying the house.
One they should find out how many people live in the house and when this is known ask about monthly utility bills for electricity gas or oil.
The bills should be for winter heating and should be over a few months.
Reluctance on the part of the seller to give this information may signal large amounts of heating costs.
If you are serious about buying the house think about two tests.
1. An air tightness test. This will give you a clear understanding as to how leaky the house is.
A very poor result will mean very high energy bills from heating.
2. A thermal test. This will show in a graphic way where the heat flows out of the house. A poor thermal image test will also result in very high energy bills.
Now most buyers look at location and it will always be the determining factor in buying but buying a substandard house in a good location isn't really sensible.
Now there are costs associated with the above but you probably could negotiate that the seller pay for half the costs of the tests if he sees you are serious.
Energy consumption is now a very important factor when considering buying a house so if the house falls way short of your ideal home in terms of energy use but has all the other ingredients such as schools location etc use the energy deficit to negotiate a better deal.
In a world as uncertain as ours the home should be a refuge and an oasis of calm.
The house you live in should be a place where you are safe and away from the pressures of everyday life.
Now a passive home is only bricks and mortar but it will give you certainty against rising fuel prices clean fresh air and as comfortable a living environment as you can hope for.
Winter our summer it is the same old reliable place where you are never too hot or too cold but just right.
It's a bit like Goldilocks's porridge "perfect"
If you are thinking about building a new home think about a house that will be boringly reliable and will give you the best results always.
Permalink -- click for full blog post "Predictability in an uncertain world"
When you embark on building a new house or renovating or adding an extension to your existing house you are confronted with a myriad of decisions.
Permalink -- click for full blog post "Passive Design and Planning"
The storage of solar heat is the simplest and most effective way of using the energy of the sun to work in your home.
Permalink -- click for full blog post "Passive solar"
No BER can assure the prospective buyer that the house performs as indicated on the BER simply because the assessor is required to make assumptions particularly with older houses.
The Passive Certificate on the other hand is measurable and will become a prized and treasured addition to any home.
Homes having this certificate will enjoy super status in the energy efficiency stakes but will also outshine every other house in terms of air quality comfort and build quality.
The passive certificate will be of enormous advantage to sellers as it separates them from other houses.
It is probable that for sale signs will incorporate"Passive standard certified" on the sales listings.
For buyers it will give the assurance and confidence that the house is of a superior quality and will require little or no energy to heat.
Finally the Passive Certification will be seen in a positive light by lenders who will understand that buyers will have more disposable income through energy savings.
Permalink -- click for full blog post "What Price a Passive House Certificate"
Energy savings in passive houses are substantial
Permalink -- click for full blog post "PASSIVE ENERGY RETROFITTING"
Passive school building.Better schools for teacher and pupil.
Permalink -- click for full blog post "Passive schools"
Solar direct gain is the simplest form of Passive solar heating. The sun enters the house via a window or aperture and is absorbed into a floor or wall.
Permalink -- click for full blog post "Direct Gain In Solar Passive Design"
Designing the perfect passive house When people look to build a house to live in they have typical criteria such as Meeting the residential needs of themselves and their family
Permalink -- click for full blog post "Perfect passive design"
Oil prices cause construction prices to rise.The sharp increase in the cost of oil will have a knock on effect in construction prices.
Oil based products in construction such as PVC in pipes and windows to oil composites in plywood and kitchen tops just make a small percentage of the myriad of materials using oil in their manufacturing process. Added to that the increase in transport costs will significantly push up the cost of construction materials
If insulation is the heart of the passive house then thermal bridging is one of the two banes of the building process.
Permalink -- click for full blog post "Thermal Bridging In Passive Houses"
What is it like living in a passive house?
Permalink -- click for full blog post "What is it like living in a passive house?"
The Passive House Planning Package is basically an excel package to assist architects and designers in designing to the Passive standard.
Permalink -- click for full blog post "PHPP software for Passive Homes"
Energy Savings in Passive Design
Permalink -- click for full blog post "Energy savings in passive houses are substantial"
When you build a passive house, the design process entails
Permalink -- click for full blog post "Heat Recovery Ventilation Systems"
The use of air recovery systems are becoming more popular as is their use in housing with greater air tightness.
Permalink -- click for full blog post " Passive air ventilation systems"
Non passive and poorly build housing gives rise to unhealthy living standards.
Permalink -- click for full blog post "Passive Air Quality"
Passive houses offer substantial savings over traditional houses in their energy use.
Permalink -- click for full blog post "Passive Energy Costs" |
In the age of uncertain house prices the tried and tested "location location location" is never truer.
The other and somewhat overlooked advantage to a house sale and to the perceived value of a home is the energy rating.
The use of a BER (building energy rating) as a generic way to rate houses is not really suitable as it fails the quality test in house building.
