Glossary of terms

This list shows English words in Alphabetical order, followed by Japanese words and then Japanese pronunciation, where a hyphen indicates a long vowel, the vowels are usually of equal length and stress, and they more or less sound like those in bat, tiff, foot, ten and not.

A​r​gon​ アルゴン [arugon]​​: An inert gas used in multi-pane windows. It insulates around 50% ​better than air.

Astroturf movements​ 人工芝運動: Groups paid for by large corporations to appear to be grass-roots organisations, often supporting their projects or fighting against regulation. A victory of capitalism over morality!

​Cellulose insulation セルロースファイバー [seruro-zu faiba-]: Fibre-based insulation made from wood fibres, sometimes loose and blowable, and sometimes pressed together and bonded with its own resins. (Not universally acclaimed.)

Eco​ エコ​​:​ see green 

EPS​ 発泡スチロール [happo- suchiro-ru]​​: Expanded polystyrene. Low-cost foam-based insulation material.​ Being foam-based it does not allow much air or water vapour to pass through. When installed it is important to avoid gaps, which can halve the performance. If used within a wooden structure in earthquake prone areas, it's possible that gaps will appear after quakes. Don't confuse with XPS​, which is much stronger, although can retain more moisture.​

​Fibre​glass​ グラスウール​​ [gurasu u-ru]: Low ​cost fibre-based insulation material. Being fibre-based the insulation performance comes from air trapped between the fibres, which can move allowing water vapour through. A vapour barrier is therefore necessary to keep the building airtight. Not particularly pleasant to handle, but once installed there are no health risks until the building is butchered or demolished.

Flashing: 雨押さえ [ame osae]: Strip of metal or other material used to waterproof a roof intersection. Ideally roofs should be designed so that flashing is not necessary since flashing will at some point lead to leaking. Intricate roof designs and chimneys make them inevitable. Valleys in roofs need them and are often invitations for leaves and other crap to collect. Water should be allowed to follow gravity, ideally with ridges, and roof eaves extending over walls. Roofs extending from walls is a less good idea, and roofs sloping into walls is a bad idea. 

Green​ グリーン​​:​ see eco

Green bling (derogatory and somewhat archaic)​: Devices, fittings and coverings that can be added to building to make them "green". According to an arbitrary calculation, 90% of the ​building's environmental performance depends on invisible elements integrated into the structure and integral to the conceptual design. The effect of green bling is often like ordering a salad with your steak in the interest of becoming vegetarian. 

Green wash​ing グリーンウォッシング​​: Portraying ​products, processes and activities as environmentally friendly without making any fundamental exchanges except in the advertising copy. (See
Kazoo blow​er​​ カズーブローアー(告発を不正にする者): ​Person who creat​es​ a lot of noise that will support the status quo and drown out ​voices of concern or dissent. (cf whistle blowing; see also astroturf)

Krypton​ クリプトン [kuriputon]​​: Another inert gas used in multi-pane windows. ​This is another 50% better at insulating than argon, and allows windows to be much thinner while reaching high performance. Since the frames will also be thinner, and frames and their thermal bridges lose the most heat in window installations, making window panes thinner may not be such a high priority. 

Low-e​ ​低E [tei i-]: A coating applied to internal window faces which has low emissivity. This reflects low-frequency back into the building, and improves the performance of windows. 

​Mineral wool​ ロックウール [rokku u-ru]: Another fibre-based insulator like fibreglass, but made from ceramics. A little more expensive than fibreglass with the same performance, but not as nasty to handle 

Natural materials​ 自然材料 [shizen zairyou]:​ ​A somewhat vague term usually ​referring to products with no synthetic chemicals, made from trees. Often these trees were planted in neat rows, cut with chainsaws, transported by diesel-powered vehicles to processing mills running on thermal power stations.

Polyurethane​ 発泡ウレタン [happo- uretan]: ​​Another foam-based insulator that performs better than polystyrene.

Stud 間柱 [mabashira]: A vertical beam between the main pillars to which walls are attached.

​Thermal bridge サーマルブリッジ・熱橋 [sa-maru burijji / nekkyo-]: ​An extra loss of heat caused by joins between insulating materials, geometry of external structures and additional non-insulating materials. Heat losses are usually calculated over areas, but thermal bridges are calculated over lengths. As insulation improves, thermal bridges become more significant since a larger proportion of heat is lost through them, and also more critical as they can result in cold spots that will attract condensation.

​Two-by-four ツウバイ [tsu-bai]:  A building technique using beams of two-by-four inches. Rigid panels such as plywood or OSB are added to two-by-four structures so the structural strength is based on the walls, where zairai koho traditionally relies on the pillars and beams for the structure. Just to add a little confusion, 2 x 4 beams measure half an inch less by they time they've been cut and dried, measuring 38 x 89 mm rather than around 50 x 100 mm that you might expect. Compared to zairai koho, two-by-four constructions is probably cheaper, stronger, easier to build, and easier to insulate. The two-by-four construction technique developed from balloon framing in the 1830s in the US. It allowed standard sizes of timber to be put together with mass-produced nails by relatively unskilled wood workers.

Vacuum 真空 [shinku-]: ​In theory the best insulation material available, since vacuums contain nothing which will conduct. This is sometimes used in multi-pane windows and insulation panels. I can't help being skeptical about the long-term performance since there is a big pressure difference between the atmosphere and the vacuum, leakage will not be zero, and eventually this will be filled with air. This may take one month, one year or ten years, but you should be planning a building to last for fifty or a hundred years.

Vapour barrier​ 蒸気障壁 [jo-ki sho-heki] :​ A membrane usually applied on the inside of the external walls, or within 25% of the insulation from the inside. This stops moisture from the internal air from getting through the walls where it would cause condensation. Some wall finishes act as vapour barriers. Highly insulated buildings should also be air tight, to prevent heat being lost or gained through leaking air. Depending on the performance, vapour barriers may also act as air barriers.

Warm edge​ ウォームエッジスペーサー [wo-mu ejji supe-sa-]: ​A technology used around the edges of multipane windows which prevents heat leaking through that weak link in the window assembly.

XPS ​押出ポリスチレン [oshidashi pori suchiren]​​: Extruded Polystyrene. The same chemical composition as EPS, but extruded rather than expanded, and stronger. Suitable for use under and around foundations.

Zairai koho 在来工法: Traditional Japanese building method using pillars, beams and braces, traditionally held together nail-free with joints designed to distribute stresses evenly. Now nails and other metal joints are used, and rigid panels are added so the structures meet earthquake regulations.