Zone5

Shelter- Future Proofing Our Homes and Buildings

This is the introduction to  week seven of the Powerdown Toolkit 10-week community learning course created by the Cultivate Center in Dublin. It has an accompanying TV show with a 30-minute episode accompanying each week of the course, soon to be aired on Dublin Community TV.

Energy and the Household

Recent increases in energy costs have spawned a huge increase in interest in “sustainable” housing with considerable improvements in some aspects of house design and construction. With a plethora of new building products and systems emerging from the industry on one hand and a burgeoning interest in natural building materials such as cob and strawbale, housing has been one of the most intensely scrutinised areas in terms of energy conservation and use. The industrial revolution that downgraded the household to the edge of economic life; the time has come now for it to reclaim its place. David Holmgren has described how this might occur for many over the first years of energy descent in his paper Retrofitting the Suburbs.

In the future, the great challenge will be to retrofit the existing housing stock to be more energy efficient. New builds will decline to a fraction of what they have been during the years and decades of industrial growth.

House Design

A Pattern Language by Christopher Alexander {1977} is a design manual for convivial housing and town planning, compiling over 240 “patterns” or design solutions many of which will both help conserve energy and build community.

“Each pattern”, says Alexander “describes a problem which occurs over and over again in our environment, and then describes the core of the solution to that problem, in such a way as you can use this solution a million times over, without ever doing it the same way twice.”

Here are a few examples of patterns in house design and function that may prove useful in the low-energy future:

1.    Living space: The house needs to be a place where families – or the extended household – lives, talks and eats together, on a regular basis.

2.    Working space: There should be a workshop, and/or a study, and/or a potting shed.  Houses will be central to the economy of the future, power houses of the local economy, and not just places for leisure and sleep.

3.    Growing space.  Most houses will need a garden or contact with a garden.  They need some way of recycling food waste and, in the longer term, of recycling, composting and reusing human waste.  Not every householder will have the aptitude to grow his or her own vegetables, but there could be reciprocal arrangements with other households that do.

4.    Located in the community.  Every household will need to participate in the community’s material economy and in its social capital.  This will have a bearing on the design of houses: they will need to be compact in layout, saving space and forming neighbourhoods, all parts of which are in easy walking distance; the neighbourhoods should be held together by its busy, sociable streets.  Gardens may vary in size: terraced houses can have long/large gardens; other gardens can be a short distance away, or in allotments.

The design and placement of buildings in towns and the squares and meeting places they define will have a big impact on the development of the community.

5.    Local materials.  Houses in the community of the future will rely on local materials, wherever possible, for construction and repair.

Energy in Housing. By Andy Wilson

Andy Wilson is an independent energy consultant working mainly in renewables and off-grip systems, as well as energy efficient house construction and retro-fitting. He has extensive experience in many other areas of self-sufficiency  including woodland management and horticulture.

He is the editor of Sustainability Magazine and co-author with Paul Lynch of the  recent Mayo Energy Audit.

Andy gives workshops and talks around Ireland on energy in housing and solar DIY.

The housing sector accounts for some 20-30% of all energy used in Ireland today. Energy use in the sector can be subdivided into three categories:

Energy used in construction (the embodied energy) Energy used to heat the dwelling Energy used to provide lighting and to run appliances

Embodied Energy

The total embodied energy in a modest dwelling made largely from locally sourced low energy materials could be as little as one twentieth  of the embodied energy in a very large house constructed entirely from high energy products or ones imported from thousands of miles away.

Size of Dwellings

The average dwelling size in Ireland is approximately 110m2. The average size of new dwellings however, is about 150m2. In tandem with this increase in size has been the gradual decease in the number of occupants per dwelling, down from about 4.0 occupants per dwelling in 1966 to only 2.9 today. Floor area in new build has now exceeded 50m2 per occupant. This compares with 20-25m2 per occupant in Eastern Europe. Heating

The energy required to heat a typical house, when measured as the quantity of energy per unit area of floor space, has been decreasing gradually in recent years owing to better standards of insulation.  This increase in energy efficiency has been largely offset by the larger size of new houses and by higher internal temperatures.  According to SEI data, the average household uses some 20,000 kWh of energy per annum for heating. Over 97% of this energy is derived from non renewable sources.

The heating requirement of a building is usually expressed as kWh/m² of floor space per annum. The figure may be as high as 500 kWh/m²/ annum in an uninsulated house,   but 50-70 kWh/m² / annum in  houses  compliant with current building regulations, and as little as 10-15 kWh/ m² / annum for a passive house. Houses described as passive often use electrical appliances for domestic water heating and for running heat recovery ventilation systems and micro heat pumps.

Reducing Energy Requirements for Heating

Keep dwelling sizes small both in floor area and volume. High ceilings waste heat: we only     occupy the bottom 1.5-2 meters of a room.

Insulate well

Minimise draughts: Airtightness in newly built houses can vary by up to a factor of six     depending on construction methods, choice of materials, design detail and standard of     workmanship.

Use the highest spec windows and external doors affordable

Avoid open chimneys

Make use of passive solar design

Improve air tightness -On average about 40% of heat losses from buildings occurs through ventilation and about 60% through the fabric of the structure, though the proportions can vary widely from building to building.

Insulation

It is estimated that about 20-30% of our entire housing stock has totally inadequate insulation (or no insulation whatsoever). Less than 5% of our housing stock is well insulated.

There are many insulation products on the market. Some are made from natural fibres and have a low embodied energy as well as being environmentally friendly. The synthetic insulation products generally have a higher embodied energy and carry a higher environmental price tag.  While some insulation products, notably the multi-layer foil insulation genre, perform very poorly, most insulation materials work well if they are installed properly. Unfortunately this is often not the case, with insulation being frequently applied poorly or not at all, for example many lofts have not been insulated at all.

In the case of retrofit on older buildings, space may be at a premium and compromises will have to be made. Even so, minimum targets to aim for should be walls 50-100mm, roofs/ceilings 200mm, and floors 50-80mm. It should be recognised that these are only ballpark figures and the depth required will also vary according to the insulation product used.

Beyond a certain point, the benefits of extra insulation are marginal, particularly as the heat losses through windows and doors may be almost as much as the losses from the floor roof and walls combined.

Thermal Mass

Thermal mass is the mass of a building which is available for use as a heat store, rather like a large storage heater.

Timber frame houses typically have low thermal mass, especially ones built on pillars which are not in contact with the ground. Houses built from stone, concrete blocks and cob all have high thermal mass. Thermal mass is only useful if it is insulated on the outside to prevent the heat simply radiating out and being lost.

Materials such as cob and hemp lime have properties which allow them to warm up more quickly than stone or concrete.

Windows and Doors

It is not widely known  that windows  (even double or triple glazed ones) conduct heat  five or even ten times as rapidly as a well insulated wall or roof. In the case of timber doors the difference is even greater. For this reason, windows should be sized according to their primary function, which is to provide light.  In terms of heat losses, timber frames perform better than PVC frames.

Almost all windows are net energy losers in wintertime, even south facing ones. For this reason, heavy curtains or internal shutters are an excellent idea.

Passive Solar

The idea behind passive solar is that solar radiation is trapped in the building behind glazing and is used as a supplementary or even principal form of heating. Most of the glazing should be on the south side of the building, but excessive glazing can lead to overheating and then heat loss through the glass at night time.

Insulation is more important than solar gain however as other heat sources- from cooking, the occupants’ metabolism (each occupant of a building is equivalent to a 80-100 watt incandescent light bulb), or electrical appliances may often warm the house more than the sun.

Internal Temperatures

No statistics are available for Ireland but in the UK,  the average internal temperatures of dwellings rose from only 12.6 ºC in 1970 to 18.9 ºC  in 2001. These averages mask the much higher and much lower temperatures which will be found in some dwellings.

One aspect of energy conservation is to change out habits and requirements- an extra piece of clothing could be just as important as extra insulation, saving money as well as carbon emissions.

Heat Losses from Pipes and Cylinders

Lagging of hot water pipes and cylinders is woefully inadequate in the majority of dwellings, irrespective of the method of heating water or whether the water being heated is for delivering to radiators or hot water cylinders. In many cases, transmission heat losses probably exceed 50%. The greater part of these losses could be eliminated by properly lagging all hot water pipes and connections, double or even triple lagging cylinders, and insulating hot presses. In most cases, the cost of doing this is extremely low. Energy Used for Lighting and Appliances

The   average annual domestic   consumption of 5000 kWh of electricity per household is at its highest level ever and is still rising as houses become bigger and are filled with an increasing number of appliances; notably televisions, computers, freezers and dishwashers.. The difference between the electricity consumption of the most energy aware households and the energy oblivious is in excess of a factor of ten.

Lighting may account for up to one fifth of the total electricity usage but this may easily be reduced by changing over to compact fluorescent lights (CFLs). CFLs use less than 25% of the energy of conventional incandescent lights for a comparable light output. As a simple rule, if a light gets hot, it means a lot of energy is being wasted as heat.  Light Emitting Diodes (LEDs) are even more efficient than compact fluorescents and may be particularly useful for background lighting or small spotlights.

A huge amount of electrical energy (up to 50% in some households) is wasted simply by leaving things switched on when not in use or by leaving appliances plugged in when they are ‘turned off’.

Final words

Think small, think simple.