- 1 A Domestic Dwelling Field of the invention The present invention relates to a domestic dwelling. 5 Background Domestic dwellings are often built to have features that are aligned with the owner's lifestyle choices. For 10 example, building layouts, construction techniques, and decorative treatments are selected to accommodate these choices. Some of the layout choices that are presently relatively popular include open plan living, and spacious internal and external entertaining areas. At the same 15 time, some owners enjoy having the opportunity to "shut off" areas of their dwelling when not in use, or to keep certain areas reserved for specific uses, such as children's play areas. 20 In light of potential climate change issues, regulations are placed on new domestic dwellings (and sometimes on renovations to existing domestic dwellings) to reduce carbon emissions. The building shell thermal performance is an important aspect of meeting these 25 regulations, since occupants use of heating and cooling systems is influenced by this performance. The present invention has been conceived in light of the above considerations. 30 Innovation divisional specification:4380199 1 - 2 Summary of the invention The present invention provides a domestic dwelling that comprises: a first room having at least one external wall system 5 that is at least partially openable; a second room that is adjacent the first room; at least one common wall system that is located between the first and second rooms; and a roof that covers both the first and second rooms, 10 wherein both the at least one external wall system and the at least one common wall system are externally rated for thermal performance of the dwelling. In certain embodiments, the common wall system is at 15 least partially openable to open the second room onto the first room. The at least one external wall system and/or the common wall system may include one or more insulated 20 glazed partitions that are movable to open the respective wall system. The, or each, partition may be a door. The width of the opening for the partition in the at least one external wall may be at least a substantial 25 portion of the length of the external wall. Similarly, the width of the opening for the partition in the common wall may alternatively or additionally be at least a substantial portion of the length of the common 30 wall. Innovation divisional specification:4380199 1 - 3 In certain embodiments, the door is a retractable door. For example, the retractable door may be any one of: a sliding, stacking, or bi-fold door. 5 The door may include weather seals around the, or each panel, of the door to minimize air leakage around each panel. In some embodiments, the first room has two or more 10 external wall systems. In certain embodiments, adjacent external wall systems of the first room are perpendicular to one another. The domestic dwelling may further comprise a heating 15 and/or cooling system, with the first room connected to the system. The heating and/or cooling system can be configured to operate in the first room independently of the rest of the dwelling. 20 Alternatively or additionally, the first room may comprise an independent heating and/or cooling system. In some preferred embodiments, the dwelling has a common floor height across the first and second rooms. 25 The at least one common wall system may also include a fixed portion that has insulation such that the fixed portion of the common wall has an R-value that is approximately the same as that of the fixed portion of the 30 at least one external wall system. It will be appreciated that the insulation of the fixed portion of the at least one external wall may be Innovation divisional specification:4380199 1 - 4 selected to suit the climate in which the dwelling is constructed. Thus, the insulation may be such that total R-value of insulation of the fixed portion of the at least one external wall system may be approximately 1.0, 1.5, 5 2.0, or 2.5, or greater. Brief description of the drawings In order that the invention may be more easily 10 understood, embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1: is a schematic floor plan of a domestic dwelling according to a first embodiment of 15 the present invention; Figure 2: is an enlarged view of the section of the floor plan indicated with the circle A in Figure 1; Figure 3: is a side elevation of the dwelling of 20 Figure 1, as viewed in the direction indicated by arrow I; Figure 4: is a side elevation of the dwelling of Figure 1, as viewed in the direction indicated by arrow I; 25 Figure 5: is a photograph taken from within the second room of the domestic dwelling according to Figure 1, the photograph looking through the first room towards the outside; 30 Figure 6: is a photograph taken from outside the domestic dwelling according to Figure 1, the photograph looking through the first room towards the second room; Innovation divisional specification:4380199 1 - 5 Figure 7: is a schematic floor plan of a domestic dwelling according to a second embodiment of the present invention; Figure 8: is an enlarged view of the section of the 5 floor plan indicated with the circle B in Figure 7; Figure 9: is a side elevation of the dwelling of Figure 7, as viewed in the direction indicated by arrow ; and 10 Figure 10: is a photograph taken from within the second room of the domestic dwelling according to Figure 7, the photograph looking through the first room towards the outside. 15 Detailed description Figures 1 to 6 illustrate a domestic dwelling 10 according to a first embodiment of the present invention. 20 The dwelling 10 has a roof 12, which in Figures 1 and 2 is indicated by broken lines showing the ridge and valley features of the roof 12. For clarity and simplicity, the roof 12 has been illustrated in Figures 1 and 2 without any eaves or verandah structures. 25 The dwelling 10 has two levels 14, 16. As shown in Figures 3 and 4, the roof 12 is discontinuous because it includes an upper section 12a, which extends over both the lower (ground) level 14 and the upper level 16. The roof 30 also includes lower sections 12b that extend over the lower (ground) level 14 only. Innovation divisional specification:4380199 1 - 6 For the purposes of this specification, the term "roof" is to be understood to include both continuous roofs and discontinuous roofs. Furthermore, the term "roof" is to be understood to include any structure that 5 covers a portion of the structure below, such as (for example) a suspended slab that also forms the floor of a balcony for an upper level. The dwelling 10 has a number of rooms for standard 10 uses, including bedrooms, bathrooms, etc. It will be appreciated that the layout of rooms, and the intended function of each room, is not directly relevant to the present invention. 15 The dwelling also has a first room 18, which has two external wall systems 20, 22 that are each partially openable, so that the first room 18 can be opened to the outside. Each external wall system 20, 22 is externally rated for thermal performance, as will be discussed in 20 detail later. In this particular embodiment, the shorter external wall system 20 includes a single opening 24 and an insulated glazed partition, which is movable to open the 25 external wall system 20. In this embodiment, the partition is in the form of door 28, mounted in the opening 24. In addition, the longer external wall system 22 includes two openings 26a, 26b and insulated glazed partitions, which are also movable to open the external 30 wall system 22. The partitions are also in the form of doors 30a, 30b, mounted in the respective openings 26a, 26b. Innovation divisional specification:4380199 1 - 7 In this embodiment, the doors 28, 30a, 30b are each in the form of 3 panel bi-fold doors. The doors 28, 30a, 30b separate the first room 18 from the external elements, so that the occupants can selectively open and close the 5 first room 18 to the elements. A second room 32 adjoins the first room 18, and is separated from the first room 18 by two common wall systems 34, 36. Each common wall system 34, 36 is 10 externally rated for thermal performance, as will be discussed in detail later. Each common wall system 34, 36 is partially openable to open the second room 32 onto the first room 18. To 15 this end, in this embodiment, each includes common wall system 34, 36 a opening 38, 40 and an insulated glazed partition that is movable to open the respective wall system. In this embodiment, the partitions are in the form of a doors 42, 44, mounted within the respective 20 opening 38, 40. In this embodiment, the doors 42, 44 are each in the form of 3-panel stacking doors. The doors 42, 44 separate the first room 18 from the second room 32. As previously stated, both the external wall systems 25 20, 22 and common wall systems 34, 36 are externally rated for thermal performance of the dwelling 10. The occupants can selectively open the doors 42, 44 to form a substantially continuous space that includes the first and second rooms 18, 32. Alternatively, the doors 42, 44 can 30 be closed to separate the first and second rooms 18, 32. In this configuration, the doors 28, 30a, 30b in the external wall systems 34, 36 can be opened without compromising the thermal performance of part of the Innovation divisional specification:4380199 1 - 8 dwelling 10 that is separated from the first room 18 by common wall systems 34, 36. The dwelling 10 has the advantage that the "energy 5 rating" of the dwelling 10 remains the same when the doors in one of the external wall systems 20, 22 or the common wall systems 34, 36 are open, and the doors in the other wall systems are closed. In other words, the thermal performance of the dwelling 10 is not compromised when the 10 doors of the external wall systems 20, 22 are open and doors of the common wall systems 34, 36 are closed. As will be appreciated, when the doors in the external wall systems 20, 22 of the dwelling 10 are open, 15 the first room 18 will be exposed to the elements such that the first room 18 will have an "outdoor" feel. When the doors 42, 44 in the common wall systems 34, 36 are open, the dwelling 10 will have an expanded open feel in which the first and second rooms 18, 32 will have the feel 20 of a larger, continuous room. Furthermore, when all doors are open, the first and second rooms 18, 32 will have the feel of a large, continuous room that is open to the elements. 25 As previously mentioned, the doors in the wall systems 20, 22, 34, 36 are externally rated for thermal performance. The doors are insulated and glazed. To increase the thermal insulating performance of the door, 30 the door may further include: at least double glazing, frame/fascia materials with low thermal conductivity, an insulated core, a gas fill (such as argon) in the cavities between the glass panes, glass panes with spectrally Innovation divisional specification:4380199 1 - 9 selective glazing, and thermal breaks between opposing major faces of the door. To minimize the transfer of hot/cool air across the 5 respective doors 28, 30a, 30b, 42, 44, the panels of the doors have weather seals around the panels. This minimizes the volume of air that leaks around the panels, which in turn minimizes the energy load associated with heating/cooling the dwelling 10. 10 Furthermore, the glass of the doors 28, 30a, 30b, 42, 44 used in the dwelling 10 is selected to have a U-value (which is a measure of the air-to-air conductance across the door) of less than 6.5. With an appropriately 15 selected Solar Heat Gain Co-efficient, the door may be rated to have at least 2.5 heating stars on the Window Energy Rating Scheme (WERS). In this embodiment, fixed portions of the common wall 20 systems 34, 36 are constructed with thermal insulation suitable for an external wall. The insulation may be bulk insulation and/or reflective insulation. The fixed portions of the wall systems may also include one or more air gaps. For example, in a brick veneer dwelling, the 25 common wall systems 34, 36 may be constructed as brick veneer walls, with the veneer on the wall surface internal to the first room 18 and with insulation material in the wall space. However, it will be appreciated that plaster, render, or similar claddings, may be applied to surfaces 30 of the common wall systems that are internal to the first room 18. Innovation divisional specification:4380199 1 - 10 Insulation provided to the fixed portions of the common wall systems is selected to match the thermal insulation characteristics of fixed portions of the external wall systems 20, 22. In other words, the total 5 R-value (which is a measure of thermal resistance of the structure) of the fixed portions of the wall systems 20, 22, 34, 36 will be substantially the same. As will be appreciated, in practice, insulation selected for the fixed portions of the external wall systems 20, 22 will be 10 appropriate for the requirements of the dwelling 10. This may be determined by a number of factors, including the climate of the region in which the dwelling 10 is constructed, and the orientation of the respective wall system. Thus, the total R-value of the fixed portions of 15 the external wall systems 20, 22 may be approximately 1.0, 1.5, 2.0 or 2.5, depending on the climate of the region in which the particular dwelling is constructed. For the purposes of this specification, the term 20 "retractable door" will be taken to mean a door that includes at least one door panel that translates (but may simultaneously rotate) between the open and closed positions. In addition, the term "retractable door" will be taken to mean a door that has at least two movable door 25 panels. Thus, in the embodiment shown in Figures 1 to 4, the doors 28, 30a, 30b, 42, 44 are all retractable doors. In this embodiment, the first room 18 may be intended for use as an entertaining area or the like. Furthermore, 30 the second room 32 is "open plan", and has a kitchen, and areas that may be intended for use as a meals area and a family room. Innovation divisional specification:4380199 1 - 11 The dwelling 10 is constructed with a common floor height across the first and second rooms 18, 32. In this way, there is no step between the two rooms. The common floor height across the two rooms ensures minimal 5 interruption at floor level, which avoids the space being "broken up" at the intersection of the two rooms. It will be appreciated that a track may be provided at floor level to support the door 42, 44 in the common walls 34, 36. 10 In embodiments in which the first and second rooms 18, 32 are constructed on a concrete slab, the slab is at a constant level between the first and second rooms 18, 32. Floor coverings may be provided to one or both of the first and second rooms 18, 32. Where both the first and 15 second rooms 18, 32 have floor coverings, it will be appreciated that each room may or may not have a different floor covering. It will be appreciated that minor changes of floor height arising from different floor coverings across the first and second rooms 18, 32 may be provided 20 whilst still maintaining the common floor height. The common floor height enhances the expanded open feel across the first and second rooms 18, 32. The roof 12 covers both the first and second rooms 25 18, 32. However, as previously noted, the roof 12 is discontinuous. In particular, the roof 12 has a number of vertical separations or "steps". As shown in Figure 1, common wall system 36 is 30 constructed such that the width of the opening 40 occupies a substantial portion of the length of the common wall system 36. Innovation divisional specification:4380199 1 - 12 In contrast, common wall system 34 is constructed such that the width of the opening 38 occupies a relatively small portion of the length of the common wall system 34. As can be seen in Figures 1 and 2, the 5 dwelling 10 includes a third room 46 that is adjacent to each of the first and second rooms 18, 32, but is not interconnected with the first room 18. Common wall system 34 also extends between the first and third rooms 18, 46. 10 The first room 18 is connected to the heating/cooling system(s) that provide temperature control to the dwelling 10. In some embodiments, the section of the heating/cooling system(s) that operate in the first room 18 may be isolated (in other words, "zoned") from the 15 sections that operate in the remainder of the dwelling 10. In this way, the heating/cooling system(s) may be operated in the dwelling 10 to the exclusion of the first room 18. Alternatively or additionally, the first room 18 may have heating and/or cooling systems that operate independently 20 of the rest of the dwelling 10. In this embodiment, the longer external wall 22 includes a gas fireplace 48, which separates the openings 26a, 26b. Each of the doors 30a, 30b is anchored to the 25 section of the external wall 22 that forms part of the fireplace 48. It will be appreciated that in alternative embodiments in which a single opening is provided in an external wall system 22, two retractable doors may be arranged to retract in opposite directions. 30 As shown in Figures 1 and 2, the external walls 20, 22 of the first room 18 intersect between openings 24, 26a. In alternative embodiments, the openings 24, 26a may Innovation divisional specification:4380199_1 - 13 be continuous, with corner entry retractable doors that close to meet at the intersection of the external wall systems 20, 22. Similarly, with regard to the intersection of the two common wall systems 34, 36. 5 In this embodiment, the external wall systems 20, 22 are perpendicular to one another. In some alternative embodiments in which the first room also has two external wall systems, the walls may be arranged at acute or obtuse 10 angles to one another. Figures 7 to 10 illustrate a domestic dwelling 110 according to a second embodiment of the present invention. Whilst having a different floor plan to the dwelling 10 15 and being a single level building, the dwelling 110 has many features similar to that of the dwelling 10 of the first embodiment. Accordingly, features of the dwelling 110 that generally correspond with features of the dwelling 10 have been assigned corresponding reference 20 numerals incremented by 100. As shown in Figure 9, the roof 112 is a continuous in that the adjacent sections or panels of the roof structure meet without any vertical separations. For clarity and 25 simplicity, the roof 112 has been illustrated in Figures 7 and 8 without any eaves or verandah structures. The first room 118 has two external wall systems 120, 122, that are partially openable to open the first room 30 118 to the outside. The external wall systems 120, 122 are each externally rated for thermal performance. Furthermore, each external wall system 120, 122 includes a single opening 124, 126, and an insulated glazed partition Innovation divisional specification:4380199 1 - 14 that is movable to open the respective external wall system 120, 122. In this embodiment, the partitions are in the form of doors 128, 130 mounted within the respective opening 124, 126. Furthermore, in this 5 embodiment, the doors 128, 130 are both 5-panel bi-fold doors. A second room 132 adjoins the first room 118, and is separated from the first room 118 by a single common wall 10 system 134. The common wall system 134 is externally rated for thermal performance. Furthermore, the common walls system 134 includes a opening 138 with an insulated, glazed partition mounted in the opening 138. The partition is in the form of a 6-panel bi-fold door 142. 15 The dwelling 110 is constructed with a common floor height across the first and second rooms 118, 132. As can be seen in the floor plan of Figure 7, the 20 dwelling 110 has a number of adjacent rooms (which are comparable to the third room 46 of the dwelling 10) that are adjacent to, but is not interconnected with, the first room 118. The function of the adjacent rooms is not important. The dwelling 110 has common wall systems 150, 25 152 between the first room 118, and the adjacent rooms. The common wall systems 150, 152 are externally rated for thermal performance. In this embodiment, the common wall systems 150, 152 are both entirely fixed. These wall systems 150, 152 are constructed with thermal insulation 30 suitable for an external wall. The insulation provided to the common wall systems 150, 152 (and also to the fixed portions of common wall system 134) will be selected to Innovation divisional specification:4380199 1 - 15 match the thermal insulation characteristics of fixed portions of the external wall systems 120, 122. The first room 118 is fitted with a galley style 5 kitchen 154, which has a sink and a cooking hob. Accordingly, the first room 118 can be used for cooking whilst entertaining. As will be appreciated, a dwelling according to the 10 present invention may be provided with two or more second rooms. Similarly, a dwelling may be provided with two or more first rooms. As will be appreciated, wall systems of the dwelling 15 may be provided with additional insulated glazed partitions in the form of windows, if desired. To maximize the thermal insulation properties of the dwelling, any such windows are also externally rated for thermal performance. 20 It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention. 25 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as 30 "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. Innovation divisional specification:4380199 1