This primary aim of this chapter is to supply a technological overview of the research subject. The first Section of the chapter provides an overview of the Closed Panel Timber Frame system. The following subdivision explains Passive House Design and the demands of a home to run into Passive House Standards. Section three will give an overview of the assorted elements that are used in Closed Panel Timber Frame building and how they meet these criterions. Finally subdivision four will offer reasoning remarks.
The Closed Panel system is based on the traditional he-man frame but with little differences. The chief difference with this system is that the insularity stuff is installed into the panel at the mill phase and this is so retained with some other bed of stuff to ‘close ‘ the panel. A controlled fabrication procedure eliminates issues with craft and quality. This ensures increased thermic public presentation with lower u-values and evaluation along with vouching bill of exchange proofing and air stringency. Another advantage of the system is in the off-site adjustment of Windowss, doors and electrical conduits. This ensures that the air barrier is non broken on-site guaranting air-tightness is maintained throughout the construction.
The thermic public presentation of a plane edifice component within a peculiar building type is described by its U-Value ( W/m2K ) . It is a step of the heat transmittal through the component per grade of temperature difference ( grades Celsius denoted as grades Kelvin to signal temperature difference ) between the internal and external environments. The U-Value is the opposite of the entire electric resistance of the constituents of a edifice component. The electric resistance of each constituent is calculated by spliting the thickness of the component by its thermic conduction.
Thermal bridging refers to a stuff, or assembly of stuffs, in a edifice envelope through which heat is transferred at a well higher rate ( due to higher thermic conduction ) than through the encompassing stuffs. Junctions between window or door and wall, wall and floor, and wall and roof should be designed carefully to avoid thermic bridging. A thermic span additions heat loss through the construction, and in some utmost instances may do surface condensation or interstitial condensation into the building. Surface mould growing or wood putrefaction may be the effects of a thermic span.
A thermic span defines an country of increased heat loss in comparing to the environing elements. There are two distinguishable types of thermal span – ‘repeat ‘ and ‘non-repeat ‘ . Repeat Thermal Bridging is where a thermic span occurs at regular intervals, for illustration in a closed panel system at the I-beams or he-man and is the type that will concern us in this survey. Repeat thermic bridging is accounted for in U-value computations. Non-repeat Thermal Bridging normally occurs at junctions of constructing elements such as a wall/floor, wall/roof or wall/window junction, etc.
The measure which describes the heat loss associated with a thermic span is its ‘ additive thermic transmission ( I? ) value and is expressed in W/mK. This is a belongings of a thermic span and is the rate of heat flow per degree per unit length of span that is non accounted for in the U-values of the plane edifice elements incorporating the thermic span.
Harmonizing to the SEI Guidelines for Passive House design on Thermal Bridges the Linear heat Coefficient I? should be less than 0.01 W/mK.
The air-tightness of a home, or its air permeableness, is expressed in footings of air escape in three-dimensional meters per hr per square meter of the brooding envelope country when the edifice is subjected to a differential force per unit area of 50 Pascals. Air-leakage ( or infiltration ) is the uncontrolled incursion of outside air into a edifice. It takes topographic point through gaps, chiefly through unequal and imperfect waterproofing between window frames and walls, between the gap subdivisions of the window and along the articulations of the edifice envelope. The brooding envelope country is defined in this context as the entire country of all floors, walls and ceilings surrounding the home, including elements bordering other heated or unwarmed infinites. Air escape is defined as the flow of air through spreads and clefts in the edifice cloth. Uncontrolled air escape increases the sum of heat loss as warm air is displaced through the envelope by colder air from exterior. Air escape of warm moistness air through the edifice construction can besides take to condensation within the edifice, which reduces insularity public presentation and causes fabric impairment.
The SEI Guidelines for Passive House design states that the Structural Air Tightness of a edifice component should be n50 & lt ; 0.6/ air alterations per hr. This means at a force per unit area of 50 Pascals the sum of air that escapes through the edifices cloth should be less than 0.6 of the entire internal volume of the edifice.
6.3 Cardinal Components of Closed Panel System to run into Passive Standard:
To accomplish the coveted U-Values, minimised thermic bridging and degrees of air tightness several constituents are indispensable. While assorted systems are available on the market some of them vary as respects the type of insularity used and how thermic bridging is minimised or eliminated.
The U-Values for a Passive House are achieved through super insulating the edifice envelope and retaining all internal additions from the residents, their activities, usage of contraptions and most significantly the Sun. It is achieved by two steps, the first being the insularity used, and secondly the deepness of this insularity. There are several types of insularity used in Closed Panel building and the type chosen depends on the demands of the interior decorator. By and large there are three types of insularity presently being used on the market in closed panel building. The first type of insularity investigated is Mineral Wool and it normally comprises of either stone or glass.
Mineral Wool: Rock-Wool is manufactured from volcanic stone, typically basalt or dolomite with an increasing proportion of recycled stuff in the signifier of briquettes. The liquefied stuff is spun into wool and little measures of rosin binder and mineral oil are added to lock the strands together and do them H2O repellant. The wool is formed into a mat, which is so carried through ovens where it is cured and compressed giving it good structural strength. Glass Wool is a mixture of naturalA sandA and recycled glass at fused together at a temperature of 1,450 A°C and the glass that is produced is converted into fibres. A rosin is added to give the coveted coherence and mechanical strength.
Fig 6.4 shows mineral wool compressed between Panels
Mineral Wool is the preferable insularity type used by Norse Homes Ltd in Co Galway. One of the primary grounds they use this type of insularity is that the thermic conduction of mineral wool does non deteriorate over clip, and remains in and around 0.04 W/mK. This ensures that the U-Value of the wall construction will stay up to Passive House Standards for the whole of its life clip. Other grounds for taking this type of insularity are because it is fire-proof, non-toxic and non-biodegradable.
Cellulose Insulation is the 2nd type of thermic insularity that will be examined and is the type favoured by Eco-Timber Frame in Cork. It is normally used when Green Merchandises are required. The cellulose insularity is from recycled newspaper and is dumbly packed between the panels and stud work. The stuff is treated with Borate, a of course happening mineral compound which greatly increases fire, wet, mold and varmint opposition.
Stephen Spillane of Eco Timber Frame says that the chief advantages for taking this type of insularity are its low thermic conduction of 0.040W/mK and good particular heat capacity which helps to smooth the warming and chilling rhythm. Another major advantage of this type is Cellulose fills walls and Michigans air infiltration better than mineral wool as the fibers of cellulose insularity are much finer. When cellulose is pneumatically installed it takes on about liquid-like belongingss that let it flux into pits and around obstructors to wholly make full walls and seal every cleft and seam. No fiberglass or stone wool stuff extras this action. Fig 6.5 shows the interpolation of cellulose insularity
Polyurethane is an organic polymer formed throughA step-growth polymerizationA by reaction of aA monomerA incorporating at least twoA isocyanateA functional groupsA with another monomer incorporating at least twoA hydroxylA ( intoxicant ) groups in the presence of aA accelerator. The chief advantage of this type of Insulation is its low thermic conduction of 0.02W/mK which allows efficient keeping of heat.
Polyurethane froth has been specially developed to increase structural strength, H2O vapor opposition and lastingness. Each of the nothingnesss in each of the panels is injected with a particular mixture of proprietary chemical so that froth is produced with both first-class insularity belongingss and besides first-class environmental certificates.
Fig 6.6 shows the mechanical interpolation of Expanded Polyurethane into panel.
6.3.2 Minimising thermic bridging:
Planing and constructing a inactive house in Ireland requires the development of building inside informations that go far beyond counsel provided ( to avoid inordinate heat losingss and local condensation ) in Building Regulations Technical Guidance Document Part L, Conservation of Fuel and Energy 2005. In Closed Panel Timber Frame walls several techniques cut down this cold bridging.
The first method is the add-on of a bed of thermic insularity on the cold side of the wall panel. This method can be used where a pit is in topographic point between the panel and external facing and ensures a uninterrupted bed of insularity without any breaks, therefore extinguishing any thermic bridging.
Figure 6.7 shows 50mm bed of pit insularity
An extra method is in the design of the he-man work and common pattern sees the usage of I-Shaped he-man. The fraction of repetition thermic bridging is well reduced due to the narrow web of the beam. While bridging is non wholly removed it is reduced below the inactive house criterions.
Fig 6.8 shows the I-shaped he-man which reduces the transmission of heat
Fig 6.9 shows a thermic image of A Closed panel with I-Beam he-man. The green indicates any cold waies and as can be seen from the image these Bridgess have been minimized.
The most modern-day method of cut downing the transmission of heat is the usage of a twin wall structural frame. Twin frame systems are based on using two standard lumber he-mans engineered to let a deeper lumber frame which can be filled with a greater measure of insularity. The twin frame system ensures that no thermic bridging occurs within the building assisting maximise insularity public presentation.
Fig 6.10 shows a Twin wall structural lumber frame
6.3.3 Guaranting Air-Tightness:
In a Closed Panel Timber Frame Wall several constituents guarantee that it meets the Passive House demands on air-tightness of n50 & lt ; 0.6/ air alterations per hr. The chief constituents are by and large the sheathing and/or vapour-barriers. It should be noted that while the extra elements of plaster, cladding insularity etc besides assist in maintaining the construction air-tight they are non portion of the air-tightness bed. The air-tightness bed is normally located at the internal face of the panel as seen in Fig.
While the overlay is by and large considered to be merely a structural component, one time spreads at the articulations are kept to a minimal it can besides provides first-class ait-tightness qualities. The intent of the vapor barrier is to maintain heat in while it keeps checkerss out.
The primary country where air escape can happen is at the articulations of the overlay and the vapour barriers. The cardinal method of forestalling this is the usage of particular air keeping adhesive tape to cover the articulations. Once this is applied right air-leakage is kept to a lower limit. There are several trade names of tapes on the market but they all work on the same rule.
Fig 6.13 shows the application of a sealant tape to a vapour barrier.
Testing for Air-tightness is done on site towards the terminal of a physique but by and large before 2nd fix woodworking such as the adjustment of window or skirting boards. This is because if there are any defects in the construction they can still be accessed for fix. Blower door proving or air force per unit area testing is the preferable method of graduating air-flow in a home. This allows the accurate measuring of air motions through the cloth of your edifice. Using graduated equipment in a standardised trial mode allows a consequence which can so be compared against other belongingss, or before trials to the same belongings.
Fig 6.14 shows the powerful fan suspended in a canvas used in the testing procedure
After analyzing the technological facet of the research subject several decisions arose. The first is that it is clear that the closed panels are made to a really high criterion which is critical for Passive House design. It can besides be concluded that Passive House enfranchisement is non achieved by several demands moving independently but in concurrence with each other. While the wall panels may be made to Passive House criterion with the remainder of the constituents in melody the home will non be certified as a whole. Finally it can be observed that the bulk of constituents are designed to hold several intents. For illustration one may assume that insularity is at that place entirely for its thermic belongingss but it can besides help with the air-tightness of the edifice. To reason it is the development of the assorted constituents mentioned that are responsible for the betterment of Low Energy design, and as the alterations in statute law, as mentioned in chapter 5, demand more from edifices engineering is bettering to co-occur with these demands.
Case Study: Survey of Eco-Build by Passive House Builders, Athenry
The intent of this chapter is study the Eco-Home constructed by Passive House Builders and demo that Closed Panel Timber Frame Construction is a suited signifier of building for inactive house design. The grounds for taking a house constructed by Passive House Builders was because they do non fabricate or utilize their ain edifice elements, alternatively direct their physiques out to tender, and hence would non be biased as towards any edifice system. To make this the chapter is divided into three chief subdivisions. The first subdivision gives an overall description of the house including its orientation
7.1 Overview of Dwelling:
The building of the Eco-House in Athenry proved to be a major challenge for Cyrill Manion of Passive House Builders. The house took five months to plan and a farther five to concept. The site chosen by the client was ideal for Passive Design. The back lift was 20 grades off full South and although there are houses on either side of the brooding over-shadowing was non a job.
The building stage of the house began in August 2009 with the installing of the insulated foundations utilizing EPS and low C concrete. The system was provided by Viking House and the foundation raft consisted of two separate densenesss of Polystyrene. Even though polystyrene is an oil based merchandise the energy used in its industry is a fraction of conventional insularity merchandises. For illustration the temperature required in the industry of stone or glass wool is approximately about 950 grades while polystyrene requires merely 110 grades. It should besides be noted that and for every 1 liter of oil used in industry around 300 liters of oil can be saved in warming. Manion says that ”the system was chosen for two primary grounds, one because it provides a wholly cold span free raft, and two because of its easiness of connexion with the closed panel wall system ” .
The clients Scott and Ann Cook gave Manion free function as to what type of building type to utilize for the envelope so Manion decided on his desired U-Values and sent the contract out to tender to both masonry and lumber frame contractors. In this stamp he included the U-Values he wanted to accomplish and that the house needed minimum thermic bridging and highly low degrees of air-tightness. He besides stated that he wanted all values to be good inside the criterions specified by the inactive institute. Another major issue that Manion had was go forthing the edifice exposed to the elements while under building taking to concrete floor absorbing wet. Therefore he wanted a physique that would be highly speedy and protected from the elements in the shortest clip possible. Incorporation of a service pit was the last petition that he made. This was non merely for the typical services such as electrical overseas telegrams but besides for the Mechanical Ventilation Heat Recovery System ( MVHR ) . The MVHR System is the lone engineering that is critical for a Passive House and it was of import that it is could be incorporated within the Air-Tight Layer.
7.2 The System:
After running it by the clients Manion decided on a Closed Panel Timber Frame construction to be supplied by Eco-TimberFrame. The panels were manufactured at their Cork based mill and transported to the site by lorry. The chosen system comprised of a twin-wall structural frame. The benefits of this were that sufficient thickness was provided to super insulate the edifice and thermic bridging was limited to the caput and base of the walls. Stephen Spillane, lead interior decorator with Eco-TimberFrame explained that “ It ‘s a twin wall building, 350mm midst with dumbly packed cellulose insularity. The cellulose utilised was Warmcell 500 from green insularity suppliers Warmcell in the United Kingdom ” . The full wall construct up from outside to inside is as follows:
13mm Cement Board
12mm Breathable Wood Panel
350mm Dumbly Packed Cellulose
12mm SmartPly OSB Sheathing
50mm Service Cavity Filled with Rockwool
12mm Internal Plaster Board
Spillane said that they were looking for advanced techniques to accomplish a high quality constructing envelope that would run into Cyril ‘s demands of being good insulated and highly airtight. Eco-TimberFrame studied what was done in Germany and Austria and finally developed this wall building. The OSB board on the interior is taped for airtightness and the wood fibre board on the outside allows the house to take a breath. It is the OSB board that provides the airtightness bed and it critical that great attention was taken when taping across all articulations with Siga tape. Manion said that ” it was the first clip they had used Ordinated Strand Board as the airtight bed but believing about it makes sense from a structural point of position ” . He explained that with a regular membrane if you of all time want to repair even a image to the wall it is really hard to make so without puncturing the barrier, nevertheless with an OSB you can repair a prison guard straight into it and it will keep its air-tightness.