Code For Sustainable Homes - Scoring Well in the Energy Section
By Paul Giesberg
The Code for Sustainable Homes is a sustainability assessment tool for new built housing. The tool is developed by the UK government and is used to set minimum sustainability standards in government sponsored residential development. In addition to this many local planning authorities are using this tool to set benchmarks for private and commercial residential development projects as well.
The Code for Sustainable Homes considers a number of topics in nine different categories. Of these categories the one on energy use can be considered as the most important category: it accounts for more than 35% of the total score. Scoring well in the energy section is therefore essential to gain a good Code for Sustainable Homes rating. In this article I review the credit requirements and discuss how feasible it is to meet each these.
Dwelling emissions rate
The first issue in the energy category regards the energy performance of the building. This is considered in relation to the national building regulations. The national building regulations set minimum requirements for the energy efficiency of a building in terms of carbon dioxide emissions.
The dwelling emissions rate issue is the biggest contributor to a good score in the energy category. A total of 27 credits are available in the energy section and there are a maxi,mum of 15 credits available in the first issue. The minimum improvement over the building regulations that is awarded with one credit is a 10% improvement. The maximum of 15 credits is available for what is referred to as a "Zero Carbon Home". In addition to reduce the regulated carbon emissions from the building with 100% over the requirements in the building regulations a number of additional requirements are put on a building to qualify for the title Zero Carbon Home. This includes a minimum standard for the Heat Loss Parameter and a requirement to prevent carbon emissions from energy used for appliances in the building. Clearly the higher reductions of carbon emissions can only be achieved when using energy generated though the use of low or zero carbon technologies. Issue 7 of the energy categories deals with low and zero carbon technologies and I will discuss this in further detail in that section.
Aside from the way energy is generated, the energy performance of the building envelope is by far the largest contributor to the energy efficiency of a building and the focus should therefore be directed to improving the energy performance of the building envelope. Improving the building performance is achieved through the use of materials that reduce the heat loss of a building. This means that materials with a large insulating value should be employed for the construction of roofs, walls and exposed floors. In addition windows that achieve a rating of the British Fenestration Rating Council in band C or better and glazed doors with U-values better than 1.5 should be used. Efficient boilers for space heating and hot water should be specified. Studies by the Carbon Trust and the Energy Saving Trust have demonstrated that a 25% reduction in the carbon emissions can readily be achieved using high specification materials that improve the energy performance of the building envelope.
A 25% improvement of the carbon emissions is awarded with 5 credits. This improvement is also a minimum requirement to achieve a total Code for Sustainable Homes rating of level 3. It is possible to achieve better than the score outlined here. For instance homes that are build to the "PassivHause" will score significantly better.
Building fabric
The Code for Sustainable Homes also awards credits for the energy performance of the building envelope directly in the second issue of the energy category. There are two credits available. When the strategy as discussed in the previous section is followed at least one of these credits and in many case both credits will be achieved.
Internal lighting
Two credits are available encouraging the use of energy efficient internal lighting. When 75% of the fixed internal fittings are dedicated energy efficient fittings both credits will be awarded. Clearly this is a simple and straightforward way to improve the CSH score.
Drying space
The fourth issue in the energy category requires the provision of an internal drying space for laundry. One credit can be awarded when there is 4 or 6 meter of drying line available. Again this is a relatively simple and low cost measure to implement.
Energy labelled white goods
Two credits are available when energy efficient white goods are installed. The energy efficiency of the appliances is taken from the EU Energy Efficiency Labelling Scheme. To qualify for the two credits the following minimum standards apply:
* Fridges and freezers or fridge-freezers A+
* Washing machines and dishwashers A
* Washer-dryers or tumble dryers B or information about the scheme when not provided
There is of course a slightly higher cost associated with better performing white goods. This would only be in the order of a few hundred pounds. Otherwise these credits are straightforward to achieve.
External lighting
Two credits are available when external space lighting and security lighting are designed for energy efficiency. Again it is relatively easy to achieve these credits at low cost.
Low or zero carbon technologies
Under issue 7 in the energy category, the Code for Sustainable Homes awards up to two credits when low or zero carbon technologies are implemented in the scheme. Because implementing these technologies will also have a significant effect on the carbon emissions of the building as described under the first issue (ENE 1), the actual gain in credits will be higher. In many cases another 2 credits will be awarded through the improvement in issue ENE 1.
To be eligible for the credits a study into the feasibility of the various technologies needs to be carried in or before RIBA stage C. In addition the low or zero carbon technologies need to contribute to a carbon emission reduction of at least 10% for one credit and 15% for two credits.
When a building design includes a high energy performance of the building envelope a significant source of the energy demand of a house lies with the need for domestic hot water. Providing a solar thermal system is a relatively cost effective way to provide about 50% of the energy required for hot water. This often accounts for a carbon reduction of more than 10% in energy efficient houses. Further improvements can be made using other technologies. It depends on the nature and the location of the project what technologies would be best suited to achieve these further reduction in carbon emissions. It is worthwhile to mention that in the UK photovoltaic cells to generate electricity will likely become much more cost effective from April 2010. From that date the new system of Feed-In-Tariffs will go live. The UK government will set minimum rates that electricity companies will pay for energy generated from small-scale installations. It is proposed that electricity generated with photovoltaic cells will receive up to 36p per kWh.
Cycle storage
There are two credits available when sufficient and dedicated space to store cycles is provided. This credit is relatively easy to achieve in detached and semi-detached houses, although more challenging when considering terraced housing or flats.
Home office
The Code for Sustainable Homes awards one credit when dedicated space is made available for the use as a home office. Although in principal this is a relatively easy and low cost credit to achieve, there is one element that requires careful consideration. The room that is chosen to be adapted to allow its use as a home office is required to have a day-lighting factor of at least 1.5%. Whilst this is not an overly onerous requirement to meet, not all rooms will necessarily meet this criterion in all new homes.
Conclusions
Focusing on the energy performance of the building envelope is an important element in a strategy for a good score within the energy category of the Code for Sustainable Homes tool. It will provide good credits in its own right, but also makes it easier to achieve the credits associated with the provision of low and zero carbon technologies. Combining these two topics should enable a project to achieve eight to ten credits. In addition to these credits, the remaining issues are usually straightforward and cost effective to implement. This would achieve another eight to ten credits. Achieving more than 70% of the available credits in the energy category is therefore feasible without having to resort to advanced methodologies for most residential development proposals.
Paul Giesberg is founder and Principal Director at Planning for Sustainability Ltd. This firm specialises in providing sustainability support to development projects such as BREEAM assessments and environmental impact assessments.
Monday, April 19, 2010
Sunday, April 18, 2010
Exterior Wall Cladding - Water Penetration
Exterior Wall Cladding - Water Penetration
By Alan Trauger
Article Word Count: 1004 [View Summary] Comments (0)
The exterior walls of buildings provide comfortable and healthy indoor environments, needed to protect us from outdoor climate change. Most serious wall problems are related to water in one way or another. Buildings need to be efficient, durable, and economical with regard to investment, operation, and maintenance costs. Increasing focus on sustainability, design, and construction have given rise to new and improved materials, technology, and energy use in buildings. Water and moisture intrusion can enter wall systems in several different ways. Water penetration and moisture intrusion have been and will continue to an issue in construction.
Rainwater can enter wall systems and cladding in several different ways. It could be driven by wind, or it may enter by gravity, or by capillary action, or by surface tension, or by differential pressure movement. A very large percentage of construction related lawsuits are filed due to water intrusion issues. It is quite likely that this trend will continue. Typically, lawsuits and problems arise as a result of the ignorance of understanding water and how to manage it both in the construction trades and the design community. The lack of a skilled workforce and increasing pressures on designers for faster work for less money greatly impact the problem.
It is important to understand the physical ways moisture can penetrate a building envelope:
o Gravity - Kinetic Energy - is the movement of rainwater down the face of the envelope or cladding surface, as well as over other sloped areas, into openings (such as cracks, holes, and flashing) encountered on the way down.
o Capillary Action (suction) - is the property where water will draw itself into permeable materials through small openings (such as cracks, joints, and small holes). For instance water getting sucked into a small crack similar to sucking on a straw due to various forces of air movement.
o Surface tension is the property that causes water to cling and run on to the underside of horizontal or nearly horizontal surfaces.
o Differential Pressure Movement is when water or water vapor is driven in the direction of lower air pressure from high pressure. For example, if a building has negative air (more air being exhausted than is being forced into it, it is considered to have negative pressure).
o Vapor Movement - through Diffusion and Air Transport. Vapor and air moves from warm toward cold driven by thermal differences (air currents) as well as the amassing or concentration of absorbed liquid material. Solar heating can take rain, heat it to vapor and drive it toward the interior space of a building.
How To Determine If Water Is Damaging A Wall System?
Be alert for water damage to the surfaces and systems, although in many cases you will not be able to any damage. If the siding is deteriorating, there is a good chance that there may be some damage behind it, However, in many cases,( i.e. metal or vinyl siding and synthetic stucco) the siding looks fine while the sheathing and the structural members lying behind the siding are deteriorating.
The ability of the system to dry often determines the amount of damage done to the cladding and the structure. Wall systems with sidings with good drying potential, such as aluminum or vinyl, may be less likely to suffer damage than synthetic stucco, for example, which has poor drying potential.
When looking at the exterior surfaces of the building, look first at the cladding materials and determine if they are in good repair. Secondly, try to determine how water might get into the wall system and whether there are any areas where you might reasonably suspect concealed damage. Inspection of the building interior should be focused on vulnerable areas that were noticed outside. In some instances the moisture getting into the building envelope will show up on the interior finishes. However, damage to wall assemblies, doesn't always show up on the building interior, at least not in the early stages.
Paying attention to the drying potential of the cladding system installed. Brick veneer systems with vented rain screens have good drying potential, whereas most stucco systems do not.
Coverings and materials placed too close to grade can have a destructive outcome. The siding should be placed at least 4" to 8" above grade to protect the system and structure from moisture damage. Visual inspection should reveal seeing some of the foundation above grade and below the siding. Foundations are designed to withstand moisture in the soil. People may not like the appearance of exposed foundation, but from a functional standpoint it is necessary.
Siding materials placed too close to the roof surfaces will also keep the materials constantly wet. Siding materials should be kept a minimum of one to two inches above the roof surface.
Planters and gardens should not be built against the home or structure. A raised planter with three sides and the building acting as the fourth side is a poor arrangement. Siding materials are not designed to be in contact the earth. Having planters against the structure can have grave implications for the buildings. Raised planters close to the building should have four sides and should be set out at least two inches from the siding. This is not a common detail, but it is a lot easier on the building.
Vines and ivy growing on buildings all tend to hold moisture against the structure and trim. This also provides pest entry opportunities. In severe case, depending upon the type of vines, root systems, or attachment nodes, can damage siding or enter building, often through trim areas, providing a direct path for moisture into the building.
What Is Needed To Protect a Building from Moisture Intrusion?
Management of the forces that drive moisture to and through the building envelope. Moisture comes in four forms - solid, liquid, vapor, and absorbed. Moisture investigation is difficult because the moisture can change forms and the analyst must hunt down all clues. Water kills buildings. Think about the ways moisture can enter a building.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings alantrauger.com/
To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
By Alan Trauger
Article Word Count: 1004 [View Summary] Comments (0)
The exterior walls of buildings provide comfortable and healthy indoor environments, needed to protect us from outdoor climate change. Most serious wall problems are related to water in one way or another. Buildings need to be efficient, durable, and economical with regard to investment, operation, and maintenance costs. Increasing focus on sustainability, design, and construction have given rise to new and improved materials, technology, and energy use in buildings. Water and moisture intrusion can enter wall systems in several different ways. Water penetration and moisture intrusion have been and will continue to an issue in construction.
Rainwater can enter wall systems and cladding in several different ways. It could be driven by wind, or it may enter by gravity, or by capillary action, or by surface tension, or by differential pressure movement. A very large percentage of construction related lawsuits are filed due to water intrusion issues. It is quite likely that this trend will continue. Typically, lawsuits and problems arise as a result of the ignorance of understanding water and how to manage it both in the construction trades and the design community. The lack of a skilled workforce and increasing pressures on designers for faster work for less money greatly impact the problem.
It is important to understand the physical ways moisture can penetrate a building envelope:
o Gravity - Kinetic Energy - is the movement of rainwater down the face of the envelope or cladding surface, as well as over other sloped areas, into openings (such as cracks, holes, and flashing) encountered on the way down.
o Capillary Action (suction) - is the property where water will draw itself into permeable materials through small openings (such as cracks, joints, and small holes). For instance water getting sucked into a small crack similar to sucking on a straw due to various forces of air movement.
o Surface tension is the property that causes water to cling and run on to the underside of horizontal or nearly horizontal surfaces.
o Differential Pressure Movement is when water or water vapor is driven in the direction of lower air pressure from high pressure. For example, if a building has negative air (more air being exhausted than is being forced into it, it is considered to have negative pressure).
o Vapor Movement - through Diffusion and Air Transport. Vapor and air moves from warm toward cold driven by thermal differences (air currents) as well as the amassing or concentration of absorbed liquid material. Solar heating can take rain, heat it to vapor and drive it toward the interior space of a building.
How To Determine If Water Is Damaging A Wall System?
Be alert for water damage to the surfaces and systems, although in many cases you will not be able to any damage. If the siding is deteriorating, there is a good chance that there may be some damage behind it, However, in many cases,( i.e. metal or vinyl siding and synthetic stucco) the siding looks fine while the sheathing and the structural members lying behind the siding are deteriorating.
The ability of the system to dry often determines the amount of damage done to the cladding and the structure. Wall systems with sidings with good drying potential, such as aluminum or vinyl, may be less likely to suffer damage than synthetic stucco, for example, which has poor drying potential.
When looking at the exterior surfaces of the building, look first at the cladding materials and determine if they are in good repair. Secondly, try to determine how water might get into the wall system and whether there are any areas where you might reasonably suspect concealed damage. Inspection of the building interior should be focused on vulnerable areas that were noticed outside. In some instances the moisture getting into the building envelope will show up on the interior finishes. However, damage to wall assemblies, doesn't always show up on the building interior, at least not in the early stages.
Paying attention to the drying potential of the cladding system installed. Brick veneer systems with vented rain screens have good drying potential, whereas most stucco systems do not.
Coverings and materials placed too close to grade can have a destructive outcome. The siding should be placed at least 4" to 8" above grade to protect the system and structure from moisture damage. Visual inspection should reveal seeing some of the foundation above grade and below the siding. Foundations are designed to withstand moisture in the soil. People may not like the appearance of exposed foundation, but from a functional standpoint it is necessary.
Siding materials placed too close to the roof surfaces will also keep the materials constantly wet. Siding materials should be kept a minimum of one to two inches above the roof surface.
Planters and gardens should not be built against the home or structure. A raised planter with three sides and the building acting as the fourth side is a poor arrangement. Siding materials are not designed to be in contact the earth. Having planters against the structure can have grave implications for the buildings. Raised planters close to the building should have four sides and should be set out at least two inches from the siding. This is not a common detail, but it is a lot easier on the building.
Vines and ivy growing on buildings all tend to hold moisture against the structure and trim. This also provides pest entry opportunities. In severe case, depending upon the type of vines, root systems, or attachment nodes, can damage siding or enter building, often through trim areas, providing a direct path for moisture into the building.
What Is Needed To Protect a Building from Moisture Intrusion?
Management of the forces that drive moisture to and through the building envelope. Moisture comes in four forms - solid, liquid, vapor, and absorbed. Moisture investigation is difficult because the moisture can change forms and the analyst must hunt down all clues. Water kills buildings. Think about the ways moisture can enter a building.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings alantrauger.com/
To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
Saturday, April 17, 2010
Building Durability With Waterproofing and Damp-Proofing
By Alan Trauger
If a structure is to be durable, nothing is more important that preventing water entry - from rain above ground and hydrostatic pressure below ground. The rainier the climate, the more rain control is needed. Gravity, wind pressure, momentum, surface tension, and capillary action can all cause rain to penetrate into a building surface. Each has been traditionally prevented by the following design techniques:
o Providing ample roof overhangs can help keep rain off the building surface.
o Avoiding straight-through openings in walls can prevent rain entry by momentum.
o Providing kerfs or drip edges can interrupt rain entry via surface tension.
o Providing flashings can direct gravity-flow rainwater back toward the building exterior.
o Providing a pressure-equalized or pressure moderated space in the air cavity behind the exterior wall face can prevent water entry via air pressure.
o Installation of roof gutters
When moisture condenses or is trapped within a wall, roof or floor assembly, it can cause structural damage as well as mold or mildew, major cause of indoor air quality problems.
It is important to recognize the transport of water vapor in air that leaks through cracks in the building envelope. The amount of moisture that can be carried through currents of air escaping through cracks and voids can pose moisture intrusion problems, and these cracks should be sealed. As warm air rises, it causes high pressure at the top of a building and low pressure at the bottom, resulting in what is called the stack effect. At these points of greater pressure differential, the attic and basement, it is especially crucial to seal air leaks and use air flow retarders. A good example of the stack effect that better illustrates these principles is a typical building elevator and its shaft. On your next elevator ride, you can sense the air flow pressures.
Under the most severe rain exposures, providing a pressure equalized (vented) space behind the exterior cladding, combined with a "drainage plane" behind that, can prevent all these modes of water entry. For low-precipitation areas, a adequate approach (with a long track record) is to provide a face-sealed exterior wall of high mass masonry or concrete, which allows rain to be stored in the wall assembly mass for later drying. The least forgiving system is a face-sealed approach with no rain-storage mass, such as exterior insulation finish systems (EIFS). This system should be used only in the driest climates, unless a water management system (a drainage plane) is included.
Asphalt-impregnated felt (or tar paper) have been traditionally used as drainage plane, but water-resistant sheathings, such as rigid insulation or foil-faced structural sheathing, can also serve the purpose. Window, door, and roof/wall intersections must be carefully detailed to ensure drainage plane continuity. Because the drainage plane is toward the outside of the wall assembly, impacts to indoor air quality from the tar paper or rigid board are typically only an issue for chemically sensitive people.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings
http://newsletters.alantrauger.com/ To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
If a structure is to be durable, nothing is more important that preventing water entry - from rain above ground and hydrostatic pressure below ground. The rainier the climate, the more rain control is needed. Gravity, wind pressure, momentum, surface tension, and capillary action can all cause rain to penetrate into a building surface. Each has been traditionally prevented by the following design techniques:
o Providing ample roof overhangs can help keep rain off the building surface.
o Avoiding straight-through openings in walls can prevent rain entry by momentum.
o Providing kerfs or drip edges can interrupt rain entry via surface tension.
o Providing flashings can direct gravity-flow rainwater back toward the building exterior.
o Providing a pressure-equalized or pressure moderated space in the air cavity behind the exterior wall face can prevent water entry via air pressure.
o Installation of roof gutters
When moisture condenses or is trapped within a wall, roof or floor assembly, it can cause structural damage as well as mold or mildew, major cause of indoor air quality problems.
It is important to recognize the transport of water vapor in air that leaks through cracks in the building envelope. The amount of moisture that can be carried through currents of air escaping through cracks and voids can pose moisture intrusion problems, and these cracks should be sealed. As warm air rises, it causes high pressure at the top of a building and low pressure at the bottom, resulting in what is called the stack effect. At these points of greater pressure differential, the attic and basement, it is especially crucial to seal air leaks and use air flow retarders. A good example of the stack effect that better illustrates these principles is a typical building elevator and its shaft. On your next elevator ride, you can sense the air flow pressures.
Under the most severe rain exposures, providing a pressure equalized (vented) space behind the exterior cladding, combined with a "drainage plane" behind that, can prevent all these modes of water entry. For low-precipitation areas, a adequate approach (with a long track record) is to provide a face-sealed exterior wall of high mass masonry or concrete, which allows rain to be stored in the wall assembly mass for later drying. The least forgiving system is a face-sealed approach with no rain-storage mass, such as exterior insulation finish systems (EIFS). This system should be used only in the driest climates, unless a water management system (a drainage plane) is included.
Asphalt-impregnated felt (or tar paper) have been traditionally used as drainage plane, but water-resistant sheathings, such as rigid insulation or foil-faced structural sheathing, can also serve the purpose. Window, door, and roof/wall intersections must be carefully detailed to ensure drainage plane continuity. Because the drainage plane is toward the outside of the wall assembly, impacts to indoor air quality from the tar paper or rigid board are typically only an issue for chemically sensitive people.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings
http://newsletters.alantrauger.com/ To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
Friday, April 16, 2010
Building Envelope and Infrared Thermography
Infrared Thermography - How it Works in Building Science
By Alan Trauger
Infrared Thermography How It Works In Building Science
Thermography enables us to see and measure heat. All materials on earth emit heat energy, in the infrared portion of the spectrum. Unfortunately, the unaided human eye cannot see in the infrared. However, infrared cameras can not only see, but record infrared images and measure the temperatures of objects quite accurately.
Infrared thermography is the technique for producing an image of invisible (to our eyes) infrared light emitted by objects due to their thermal condition. The most typical type of IR camera resembles a typical camcorder and produces a live TV picture of heat radiation. More sophisticated cameras can actually measure the temperature of any or surface in the image and produce false color color images that make interpretation of thermal patterns easier. An image produced by an infrared camera is called a thermogram or sometimes a thermograph.
Objects are characterized by a variety of physical by a variety of physical parameters such as size, shape, and weight. The most frequently measured physical property is temperature. Heat is the byproduct of all work, whether it comes from electrical, mechanical, or chemical activity. Humans generate, contain, and transfer heat to run our industries and regulate our everyday environments. Unexpected temperature variations may indicate design flaws, poor workmanship, or damaged building components. Temperature variations can be used to recognize numerous anomalies.
Heat is an intangible thing. We cannot directly measure heat. We can only measure the effects of heat; namely by a temperature change. The amount of heat necessary to change the temperature of an object depends on the objects heat capacity. Thermography can pinpoint leaks in roofing and other building materials by exploiting the thermal properties of water. Water stores heat very well; it warms up or cools down more slowly than other materials common in buildings. This property is called "specific heat" by physicists.
Infrared Surveys are a quick and cost effective approach for assessing hidden water damage. Because the heat capacity of water damaged material is greater than that of dry material and air, areas of high moisture content appear warmer or colder than the surrounding infrastructure. Infrared scanning makes finding problem areas much easier. Combined with digital photography, it can greatly enhance the consumers understanding of just what the problem is and how to go about having it repaired. It also enhances the consumers ability to deal with the contractors that may be performing the repair work.
Infrared imaging allows us to evaluate the condition of the exterior cladding systems by mapping areas of moisture entrapment and the delamination due to environmental stress. Exterior cladding surveys are extremely cost effective, surveys are all non destructive. To a building owner or insurance company involved in property damage settlement, clear images of normally invisible damage can be invaluable for planning restoration efforts and rationalizing settlements.
Building envelope performance is vitally important for energy efficiency as well as occupants safety and comfort. An infrared scan may help detect or resolve hidden electrical, plumbing, insulation voids, storm drainage or structural problems, minimize risks and maintenance costs. Although infrared inspection does not directly detect mold, it is quite useful to find hidden moisture, where mold may develop.
How does Infrared fit into the Big Picture: It is a non destructive test that is able to detect problems before physical symptoms appear. Use to optimize building envelope performance to reduce energy costs. Increase building durability through timely minor repairs and reduces life cycle costs.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings http://newsletters.alantrauger.com/ To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
By Alan Trauger
Infrared Thermography How It Works In Building Science
Thermography enables us to see and measure heat. All materials on earth emit heat energy, in the infrared portion of the spectrum. Unfortunately, the unaided human eye cannot see in the infrared. However, infrared cameras can not only see, but record infrared images and measure the temperatures of objects quite accurately.
Infrared thermography is the technique for producing an image of invisible (to our eyes) infrared light emitted by objects due to their thermal condition. The most typical type of IR camera resembles a typical camcorder and produces a live TV picture of heat radiation. More sophisticated cameras can actually measure the temperature of any or surface in the image and produce false color color images that make interpretation of thermal patterns easier. An image produced by an infrared camera is called a thermogram or sometimes a thermograph.
Objects are characterized by a variety of physical by a variety of physical parameters such as size, shape, and weight. The most frequently measured physical property is temperature. Heat is the byproduct of all work, whether it comes from electrical, mechanical, or chemical activity. Humans generate, contain, and transfer heat to run our industries and regulate our everyday environments. Unexpected temperature variations may indicate design flaws, poor workmanship, or damaged building components. Temperature variations can be used to recognize numerous anomalies.
Heat is an intangible thing. We cannot directly measure heat. We can only measure the effects of heat; namely by a temperature change. The amount of heat necessary to change the temperature of an object depends on the objects heat capacity. Thermography can pinpoint leaks in roofing and other building materials by exploiting the thermal properties of water. Water stores heat very well; it warms up or cools down more slowly than other materials common in buildings. This property is called "specific heat" by physicists.
Infrared Surveys are a quick and cost effective approach for assessing hidden water damage. Because the heat capacity of water damaged material is greater than that of dry material and air, areas of high moisture content appear warmer or colder than the surrounding infrastructure. Infrared scanning makes finding problem areas much easier. Combined with digital photography, it can greatly enhance the consumers understanding of just what the problem is and how to go about having it repaired. It also enhances the consumers ability to deal with the contractors that may be performing the repair work.
Infrared imaging allows us to evaluate the condition of the exterior cladding systems by mapping areas of moisture entrapment and the delamination due to environmental stress. Exterior cladding surveys are extremely cost effective, surveys are all non destructive. To a building owner or insurance company involved in property damage settlement, clear images of normally invisible damage can be invaluable for planning restoration efforts and rationalizing settlements.
Building envelope performance is vitally important for energy efficiency as well as occupants safety and comfort. An infrared scan may help detect or resolve hidden electrical, plumbing, insulation voids, storm drainage or structural problems, minimize risks and maintenance costs. Although infrared inspection does not directly detect mold, it is quite useful to find hidden moisture, where mold may develop.
How does Infrared fit into the Big Picture: It is a non destructive test that is able to detect problems before physical symptoms appear. Use to optimize building envelope performance to reduce energy costs. Increase building durability through timely minor repairs and reduces life cycle costs.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings http://newsletters.alantrauger.com/ To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
Thursday, April 15, 2010
Building Envelope Maintenance
Building Envelope Maintenance
By Alan Trauger
A Building Envelope is the separation between the interior and exterior environments of a building. It is the outer shell, or elements including the foundation, walls including windows and doors, and roof. Properly designed and constructed it will control heat flow, control air flow, control water vapor flow, control rain penetration, control light, solar, and other radiation, control noise, control fire, provide strength and rigidity, be durable, be aesthetically pleasing, and most importantly be economical.
A building envelope is a system of interdependent parts. Like other types of systems, the whole unit functions only as well the least effective component. When making improvements, the system should be considered as a whole. If the entire system is not working at maximum effectiveness, conditioned air inside a building will find a way to escape: unwanted outside air will find a way to enter.
It is obvious and a known fact that roofs will leak and may require periodic maintenance or replacement. Many people do not realize that the other elements of the building envelope can be the main culprits for moisture entry intrusion. An important element when determining the source of a problem is the wall system. For the wall system to function as intended, several factors must be taken into consideration, including the selection and design of compatible materials and systems, proper detailing of material junctions and terminations installation and inspection of these details during construction, the ability to composite envelope systems to function during weather cycles, and proper maintenance skilled and trained trades. Even the slightest difference between the way a wall system was designed and how it was actually constructed can have a major impact on performance.
Maintenance: Crucial Key To Proper Performance
Proactive maintenance should encompass the following components for both residential and commercial properties: annual maintenance budget, regular building condition assessments, annual proactive maintenance, and seasonal visual changes. Integrating maintenance into funding into the yearly budget is essential for those committed to a property over the long term, and a regular review of the buildings condition is a way to assess the remaining life expectancies of the materials. This is the only way for tasks such as sealant and weatherstriping replacement, window glazing, painting, coatings, and more to be integrated into the household or operating budget.
Windows and doors - Many window and doors found in present day properties were designed for an era when energy was less expensive to purchase. As energy costs increase, windows and doors play a critical role in the envelope system. An energy efficient building envelope provides numerous benefits to property owners. It reduces the load on the mechanical systems in the building. When heating and cooling systems do not have as much variation in temperatures to regulate, energy consumption drops. Energy efficient building envelopes are becoming increasingly important to building owners due to stricter government regulations. Newer building codes are now mandating higher levels of energy efficiency, a trend that will likely continue in the future.
As a general rule of thumb, the building envelope accounts for 35% to 40% of a typical buildings energy consumption. Using this as a guide, we can roughly determine the amount of money our envelope is costing by dividing our total annual energy costs by the number 3. If the amount is insignificant, obviously we are doing a better than average. If however, the amount is significant, we need to do some investigation.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings http://newsletters.alantrauger.com/
To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
By Alan Trauger
A Building Envelope is the separation between the interior and exterior environments of a building. It is the outer shell, or elements including the foundation, walls including windows and doors, and roof. Properly designed and constructed it will control heat flow, control air flow, control water vapor flow, control rain penetration, control light, solar, and other radiation, control noise, control fire, provide strength and rigidity, be durable, be aesthetically pleasing, and most importantly be economical.
A building envelope is a system of interdependent parts. Like other types of systems, the whole unit functions only as well the least effective component. When making improvements, the system should be considered as a whole. If the entire system is not working at maximum effectiveness, conditioned air inside a building will find a way to escape: unwanted outside air will find a way to enter.
It is obvious and a known fact that roofs will leak and may require periodic maintenance or replacement. Many people do not realize that the other elements of the building envelope can be the main culprits for moisture entry intrusion. An important element when determining the source of a problem is the wall system. For the wall system to function as intended, several factors must be taken into consideration, including the selection and design of compatible materials and systems, proper detailing of material junctions and terminations installation and inspection of these details during construction, the ability to composite envelope systems to function during weather cycles, and proper maintenance skilled and trained trades. Even the slightest difference between the way a wall system was designed and how it was actually constructed can have a major impact on performance.
Maintenance: Crucial Key To Proper Performance
Proactive maintenance should encompass the following components for both residential and commercial properties: annual maintenance budget, regular building condition assessments, annual proactive maintenance, and seasonal visual changes. Integrating maintenance into funding into the yearly budget is essential for those committed to a property over the long term, and a regular review of the buildings condition is a way to assess the remaining life expectancies of the materials. This is the only way for tasks such as sealant and weatherstriping replacement, window glazing, painting, coatings, and more to be integrated into the household or operating budget.
Windows and doors - Many window and doors found in present day properties were designed for an era when energy was less expensive to purchase. As energy costs increase, windows and doors play a critical role in the envelope system. An energy efficient building envelope provides numerous benefits to property owners. It reduces the load on the mechanical systems in the building. When heating and cooling systems do not have as much variation in temperatures to regulate, energy consumption drops. Energy efficient building envelopes are becoming increasingly important to building owners due to stricter government regulations. Newer building codes are now mandating higher levels of energy efficiency, a trend that will likely continue in the future.
As a general rule of thumb, the building envelope accounts for 35% to 40% of a typical buildings energy consumption. Using this as a guide, we can roughly determine the amount of money our envelope is costing by dividing our total annual energy costs by the number 3. If the amount is insignificant, obviously we are doing a better than average. If however, the amount is significant, we need to do some investigation.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings http://newsletters.alantrauger.com/
To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
Wednesday, April 14, 2010
What Really Happens To Make A Building Envelope Fail
There are many factors that contribute to the failure of a building envelope, and this article discusses these factors.
Building Envelope Failures Contributing Factors
By Alan Trauger
Water related factors of deterioration to buildings may take the largest toll on structures which are snow, rain, moisture, internavl condensation, and humidity. Biological factors include fungi, bacteria, and insects. Chemical contributors may include oxidizing agents, i.e bleach, reducing agents, i.e. sulfides, acids, i.e. bird droppings, bases, i.e lime, salts, i.e. chlorides, or even chemically neutral substances such as fat or oil. Solar radiation, air quality, freeze thaw effects and wind are other environmental contributors to building deterioration.
The majority of building envelope failures can be attributed to water, in one of its many forms (gas, liquid, and solid). The sources of water that could affect a building envelope include:
Water ingress and absorption. Water ingress is typically a function of moisture load and enclosure resistance. Most materials or systems have the capability to absorb some water for a defined period of time without degradation..If absorbed moisture is allowed to sufficiently dry prior to the period which degradation will occur, then these materials could achieve reasonable durability despite the absorption of water. Enclosure assemblies can show signs of water entry due to forces such as gravity, capillary action, or wind blown water. Material deterioration can occur if the water ingress cannot be managed or drained to the exterior, or if materials do not have the capability to store water without degradation.
Condensation. Condensation occurs on a surface with a temperature below the dew point of the air in which it exists. The likelihood or extent of condensation is related to the relative humidity of the air and material temperatures. Problematic condensation within building envelopes is often related to uncontrolled air leakage, vapor diffusion, rain penetration, or snow melt. Condensation is typically controlled through the careful design and installation of air and vapor barriers.
High RH levels. Although condensation is typically the result of high micro climate RH levels, situations can exist where materials are damaged due to sustained high RH levels without condensation (i.e. mold growth)
Deterioration factors in concrete
o Physical processes - freeze / thaw, abrasion, thermal cracking
o Carbonation and ingress of chlorides, leading to a risk of reinforcement corrosion in the presence of water and oxygen
o Chemical attack - includes the external attack of sulfates and acids, and internal attack of alkali aggregate reaction.
Deterioration factors in steel
o Corrosion is a major deterioration factor in steel, which need a combination of water and oxygen to corrode.
o Corrosion may be provoked by particularly aggressive environments.
Deterioration factors in timber
Main durability risk factors in timber are moisture, insects and fungi. From these, the following durability issues can arise:
o Deformation of members due to moisture movement
o Fungal decay (dry and wet rot) and insect attack ( wood boring beetles and termites)
o Structural performance phenomena can occur like reduction in strength and stiffness.
Air and Air Pollutants
Air and its components - oxygen, nitrogen, and other by-products can be an agent for deterioration, as well as a transportation mechanism. As a transportation mechanism, air can bring moisture, water, and pollutants to areas of the building envelope that would normally be protected from these agents. Moist air traveling through a building envelope can result in mold growth on organic materials or corrosion on metallic materials. Common air contaminants include chlorides in maritime climates, sulphur dioxide from vehicle emissions, hydrochloric acid near manufacturing plants, nitric acid from fossil fuel combustion, and chlorine in pool environments. Buildings located in environments with these high concentrations of reactive contaminants can experience more rapid degradation of a variety of building envelope components.
Wind
Wind plays an important role in the service life of building materials. Enclosure design requires consideration for peak loading as well as cyclical loads that cause shortened life from "overworked" materials. Wind loading can also cause depressurization of enclosure cavities, which can increase air leakage, water ingress, moisture movement and condensation. Wind pressures are also responsible for uplift on roofing assemblies and wind driven rain that can penetrate unprotected areas.
Biological and Ecological Agents
Molds or fungi, as well as rodents, insects, and birds can affect the service life of building materials. The presence of fungi, tempered air and moisture (typically above 22% moisture content in wood materials) can cause deterioration of organic materials and unacceptable occupant health conditions.
Insects, birds, and rodents can damage materials by digesting, gnawing, nesting or depositing corrosive droppings. Vegetation in the form of vertical vines or horizontal landscaping can significantly impact building fascades and structural elements due to root growth.
Temperature
Extreme temperatures or temperature fluctuations can cause significant movement in materials like copper and vinyl, creating deformation of materials, and unintended gaps and hole at material junctures. Freezing temperature can lead to frost heaving, ice jacking, spalling of masonry and damage to brittle materials. Excessive heating of materials (i.e. metal flashing and roofing can lead to "bleeding" of materials onto finished cladding, and material cracking, bulging or ridging. Extremely hot temperature, such as those that might occur in building fires can have a multitude of detrimental effects with respect to service life. These temperatures can temporarily or permanently change the physical properties of materials, making them ineffective for their intended use.
Solar Radiation
Material selection and the assembled enclosure can be greatly influenced by UV radiation from the sun. When material absorbs radiation from the sun, energy is produced that can cause a chemical reaction and material property changes (i.e., becoming brittle, yellowing, chalking, or fading). Most assemblies with UV sensitive material require the use of a covering material (i.e., metal flashing over exposed roofing membrane), limiting building aesthetic and design options. Other materials have limited service life as a result of UV degradation (i.e., many sealant materials and water based paint finishes). Conversely, night sky radiation can also cause heat loss and problems with condensation and corrosion in some roofing assemblies (i.e. zinc roofing)
Chemical Reactions and Incompatibility
Although chemical reactions are not a specific environmental agent, they are typically coupled with environmental agents to cause damage (i.e. corrosion).
For example, galvanic corrosion is a typical problem with incompatibility between metals, or the use of pressure treated wood and zinc coated fasteners. Other compatibility issues include the use of various coatings, caulking, and membranes in contact with each other.
Positive Aspects of Agents Affecting Building Durability
There are some positive side effects that impact the service life due of building materials. For example, patina corrosion protects copper roofs, temperature shifts dry moist materials, landscaped or green roofs protect UV sensitive roofing materials, wind cools buildings, and water running over zinc strips minimizes algae growth.
HOW CAN DURABILITY AND SERVICE LIFE BE IMPROVED?
The main culprits that can rob durability are poor workmanship and lack of knowledge of the properties of materials. It is important to identify the problems that manifest themselves as shortcomings in our traditional materials and look for opportunities to improve material performance in housing and buildings. Explore new techniques, materials, components and systems that promise to improve durability while reducing life-cycle costs. Develop methods for accelerated assessment of materials, components and systems that reflect in-place builder installed performance. Greater attention should be paid to details which influence how a structure deals with water run off and drainage.
Building components require varying degrees of maintenance, repair and replacement during the life cycle of a building. The extent and intensity of maintenance, repair and replacement varies significantly, depending on how appropriately the service life of materials, assemblies, and systems are harmonized, and how accessible they are for periodic maintenance, and replacements.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings http://newsletters.alantrauger.com/
To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
Building Envelope Failures Contributing Factors
By Alan Trauger
Water related factors of deterioration to buildings may take the largest toll on structures which are snow, rain, moisture, internavl condensation, and humidity. Biological factors include fungi, bacteria, and insects. Chemical contributors may include oxidizing agents, i.e bleach, reducing agents, i.e. sulfides, acids, i.e. bird droppings, bases, i.e lime, salts, i.e. chlorides, or even chemically neutral substances such as fat or oil. Solar radiation, air quality, freeze thaw effects and wind are other environmental contributors to building deterioration.
The majority of building envelope failures can be attributed to water, in one of its many forms (gas, liquid, and solid). The sources of water that could affect a building envelope include:
Water ingress and absorption. Water ingress is typically a function of moisture load and enclosure resistance. Most materials or systems have the capability to absorb some water for a defined period of time without degradation..If absorbed moisture is allowed to sufficiently dry prior to the period which degradation will occur, then these materials could achieve reasonable durability despite the absorption of water. Enclosure assemblies can show signs of water entry due to forces such as gravity, capillary action, or wind blown water. Material deterioration can occur if the water ingress cannot be managed or drained to the exterior, or if materials do not have the capability to store water without degradation.
Condensation. Condensation occurs on a surface with a temperature below the dew point of the air in which it exists. The likelihood or extent of condensation is related to the relative humidity of the air and material temperatures. Problematic condensation within building envelopes is often related to uncontrolled air leakage, vapor diffusion, rain penetration, or snow melt. Condensation is typically controlled through the careful design and installation of air and vapor barriers.
High RH levels. Although condensation is typically the result of high micro climate RH levels, situations can exist where materials are damaged due to sustained high RH levels without condensation (i.e. mold growth)
Deterioration factors in concrete
o Physical processes - freeze / thaw, abrasion, thermal cracking
o Carbonation and ingress of chlorides, leading to a risk of reinforcement corrosion in the presence of water and oxygen
o Chemical attack - includes the external attack of sulfates and acids, and internal attack of alkali aggregate reaction.
Deterioration factors in steel
o Corrosion is a major deterioration factor in steel, which need a combination of water and oxygen to corrode.
o Corrosion may be provoked by particularly aggressive environments.
Deterioration factors in timber
Main durability risk factors in timber are moisture, insects and fungi. From these, the following durability issues can arise:
o Deformation of members due to moisture movement
o Fungal decay (dry and wet rot) and insect attack ( wood boring beetles and termites)
o Structural performance phenomena can occur like reduction in strength and stiffness.
Air and Air Pollutants
Air and its components - oxygen, nitrogen, and other by-products can be an agent for deterioration, as well as a transportation mechanism. As a transportation mechanism, air can bring moisture, water, and pollutants to areas of the building envelope that would normally be protected from these agents. Moist air traveling through a building envelope can result in mold growth on organic materials or corrosion on metallic materials. Common air contaminants include chlorides in maritime climates, sulphur dioxide from vehicle emissions, hydrochloric acid near manufacturing plants, nitric acid from fossil fuel combustion, and chlorine in pool environments. Buildings located in environments with these high concentrations of reactive contaminants can experience more rapid degradation of a variety of building envelope components.
Wind
Wind plays an important role in the service life of building materials. Enclosure design requires consideration for peak loading as well as cyclical loads that cause shortened life from "overworked" materials. Wind loading can also cause depressurization of enclosure cavities, which can increase air leakage, water ingress, moisture movement and condensation. Wind pressures are also responsible for uplift on roofing assemblies and wind driven rain that can penetrate unprotected areas.
Biological and Ecological Agents
Molds or fungi, as well as rodents, insects, and birds can affect the service life of building materials. The presence of fungi, tempered air and moisture (typically above 22% moisture content in wood materials) can cause deterioration of organic materials and unacceptable occupant health conditions.
Insects, birds, and rodents can damage materials by digesting, gnawing, nesting or depositing corrosive droppings. Vegetation in the form of vertical vines or horizontal landscaping can significantly impact building fascades and structural elements due to root growth.
Temperature
Extreme temperatures or temperature fluctuations can cause significant movement in materials like copper and vinyl, creating deformation of materials, and unintended gaps and hole at material junctures. Freezing temperature can lead to frost heaving, ice jacking, spalling of masonry and damage to brittle materials. Excessive heating of materials (i.e. metal flashing and roofing can lead to "bleeding" of materials onto finished cladding, and material cracking, bulging or ridging. Extremely hot temperature, such as those that might occur in building fires can have a multitude of detrimental effects with respect to service life. These temperatures can temporarily or permanently change the physical properties of materials, making them ineffective for their intended use.
Solar Radiation
Material selection and the assembled enclosure can be greatly influenced by UV radiation from the sun. When material absorbs radiation from the sun, energy is produced that can cause a chemical reaction and material property changes (i.e., becoming brittle, yellowing, chalking, or fading). Most assemblies with UV sensitive material require the use of a covering material (i.e., metal flashing over exposed roofing membrane), limiting building aesthetic and design options. Other materials have limited service life as a result of UV degradation (i.e., many sealant materials and water based paint finishes). Conversely, night sky radiation can also cause heat loss and problems with condensation and corrosion in some roofing assemblies (i.e. zinc roofing)
Chemical Reactions and Incompatibility
Although chemical reactions are not a specific environmental agent, they are typically coupled with environmental agents to cause damage (i.e. corrosion).
For example, galvanic corrosion is a typical problem with incompatibility between metals, or the use of pressure treated wood and zinc coated fasteners. Other compatibility issues include the use of various coatings, caulking, and membranes in contact with each other.
Positive Aspects of Agents Affecting Building Durability
There are some positive side effects that impact the service life due of building materials. For example, patina corrosion protects copper roofs, temperature shifts dry moist materials, landscaped or green roofs protect UV sensitive roofing materials, wind cools buildings, and water running over zinc strips minimizes algae growth.
HOW CAN DURABILITY AND SERVICE LIFE BE IMPROVED?
The main culprits that can rob durability are poor workmanship and lack of knowledge of the properties of materials. It is important to identify the problems that manifest themselves as shortcomings in our traditional materials and look for opportunities to improve material performance in housing and buildings. Explore new techniques, materials, components and systems that promise to improve durability while reducing life-cycle costs. Develop methods for accelerated assessment of materials, components and systems that reflect in-place builder installed performance. Greater attention should be paid to details which influence how a structure deals with water run off and drainage.
Building components require varying degrees of maintenance, repair and replacement during the life cycle of a building. The extent and intensity of maintenance, repair and replacement varies significantly, depending on how appropriately the service life of materials, assemblies, and systems are harmonized, and how accessible they are for periodic maintenance, and replacements.
Alan Trauger is a Building Consultant that performs property condition assessments for residential and commercial properties. An experienced and knowledgeable problem solver, understanding processes and issues related to building structures and their systems. An expert witness, trainer, and educator. To view past newsletters on construction and buildings http://newsletters.alantrauger.com/
To review authors bio, qualifications, and interest in receiving future email newsletters http://www.alantrauger.com
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