The design process

In this section:
Four-stage design process
What to change? Dreams and fantasies
What to work with? Orientation and site
Existing energy consumption and heat loss
Designing

FOUR-STAGE DESIGN PROCESS
We followed a four-stage design process:.

• It started by discussing how we wanted the house to feel and what we needed it to do. Like permaculture, environmental architecture should start with solutions to people’s needs that save them energy in their lives.

• The second stage was looking at what we already had to work with- existing structures and materials, the opportunities provided by the site and orientation to the sun.

• The third stage was to make our own audit of the existing performance of the house, obtain a full set of energy readings, and look carefully at the main areas for heat loss. That way we could prioritise changes to bring the biggest improvements.

• Finally- the design stage; seeking ways to meet these needs, using the opportunities of the existing property, in ways that respect the environment, but also met the conservative standards of building inspectors.

DESIGN PROCESS: 1. WHAT TO CHANGE? - DREAMS AND FANTASIES
The Yellow House had been cheap to buy because of four main areas in urgent need of renovation. These could no longer be put off:

• replacing the kitchen which was falling apart, filthy and a flourishing rat habitat

• replacing the extension which was rotting through, infested with wasps, and due to collapse

• renovating the water and heating system which was old and inefficient

• fully renovating the bathroom which had ugly stained fittings and mold on the walls

We wrote these down first then talked freely about our dreams and wrote down ideas as they came to us. Many ideas started with feelings- Annie wanted a house that felt fresh and bright and healthy, which didn’t feel cluttered where we could clean in the corners. She wanted a higher degree of privacy and hated the downstairs bathroom (filthy, damp and unprivate). I wanted a house that felt different from other peoples and felt exciting to live in. After years of environmental campaigning, I wanted to feel proud of a house that entailed as few environmental compromises as possible. As we spoke through what we wanted from our life in the house and how we would live in it, five main needs came into focus:

• a well lit workspace for Annie's art projects, so she could spread out her work things without having to constantly tidy them up

• enough space for one or two children

• a spare bedroom for visitors

• a warm, dry, pleasant, upstairs bathroom

• lots of storage space

We only had three rooms upstairs. Including a bedroom for ourselves, this list required between five and six upstairs rooms. Even if we forgot about one of the hypothetical children, we still needed to find two additional rooms. Whilst we continued to consider our options, I read widely on environmental design and studied how the existing house functioned.

DESIGN PROCESS: 2. WHAT TO WORK WITH? ORIENTATION AND SITE
The front of the house faces south west, which, though not ideal, is within the bounds of viability for capturing solar energy in winter (more on orientation and solar energy...) The house overlooks open fields to the southwest, and the house receives the full winter sun until sunset.

An ideal house would face due south with no obstacles of any kind between south East and South West. South facing houses are rare to come by, and it is even rarer to have open vistas in any direction. All in all, the Yellow House is reasonably well orientated; what it loses in sun from not facing due south is partly compensated by the open aspect to the South West.

The house is located at the bottom of the shallow Thames valley, so is partly sheltered. Nonetheless, the house faces the cold winter winds which come directly across the open fields to the South West. In this respect the open aspect to the South West is a disadvantage. When the front door is opened in winter, cold air can force its way deep into the house.

DESIGN PROCESS: 3. EXISTING ENERGY CONSUMPTION AND HEAT LOSS
HEAT LOSS
We made a thorough inventory of the existing energy consumption. We found that the heat loss through the extension was truly appalling. Neither walls nor floor were insulated. The ceiling of the extension was a sheet of 5 mm hardboard. There was a 100mm square hole in one corner through which one could see the tiles. The rear wall of the extension had single glazing in leaking frames on one concrete block thick walls. Cold air could enter through the holes and through a large air vent in the door required by law to provide ventilation for the gas boiler. All in all, a well sealed tent could have had superior heat retention.

The other main sources for heat loss were the wall of the rear bedroom and office, the bathroom, the front door, the living room floor and the roof. The bathroom and toilet were built of single block concrete. There was no insulation of floor, walls or roof. The front door was aluminium and glass, both poor insulators. Because it faces south west, cold air is always trying to find an entry and there were constant draughts around the base and sides and through the letter box. The living room floor was not insulated and cold damp air freely circulated underneath it and infiltrated the house through gaps in the floor, the skirting, and the cupboard under the stairs.

There was already some fibre glass insulation in the attic but it did not cover the joists, and did not extend under the eaves. The 10% of the first floor ceiling which was under the eaves was not insulated at all. The hatch to the attic was not insulated or draught proofed.

DESIGN PROCESS: HEATING SYSTEMS
The boiler was well maintained for its 15 years, but far less efficient than a newer condensing boiler and approaching the end of its designed lifespan. It fed five radiators. Hot water was stored in a tiny poorly lagged copper tank, which predated the rest of the heating system. The plumber had no idea of how old it was other than "bloody ancient".

DESIGN PROCESS: ENERGY CONSUMPTION
I obtained gas bills for the house dating back to March 1997, and electric bills dating back to November 1997 from the power supply companies. I disregarded all estimated meter readings- they can often be wildly inaccurate. I crunched the numbers and came up with the best average I could. During the summer, the only gas consumption was for hot water, so from this I could calculate how much of the house’s energy was going into water heating, and how much was going into space heating.

Annual gas consumption: 554 units
Hot water consumption: 240 units @20 units per month
Annual space heating: 314 units
Annual electricity consumption: 3,100 kWh

DESIGN PROCESS: 4. DESIGNING
In each decision, the first stage was to develop options of how to get the best use of a limited space within the restraints of cost and convenience. Each option was then examined in the light of the principles of environmental design and a final decision reached that seemed like a reasonable compromise. (for more on the environmental design principles....)

DESIGN PROCESS: BATHROOM
Moving the bathroom upstairs turned out to be the demand from which all other aspects of the design followed. There were three options:

• The simplest and cheapest option was to convert one of the rear bedrooms to a bathroom.

• Alternatively we could build the rear extension up to two storeys, and put the bathroom (and maybe even an extra room) in the first floor of the extension.

• The third option was to keep three bedrooms, but somehow to carve out a bathroom between them.

The first option was immediately ruled out. We needed to add two rooms in all, and this would have replaced one existing room with another, still leaving us two rooms short. It would also have reduced the number of bedrooms to two with a ruinous effect on the value of the house.

The second option was more viable. The problem this created, though, was how to gain independent access to the additional room- vital for both convenience and building regulations. The only possibilities were stairs from below or a corridor to the back. Both cases entailed a waste of precious space and great expense. What is more, to avoid blocking light and air to the back rooms, the extension would have had to stick out from the rear of the house. This is a clumsy configuration, though common in Victorian houses.

The third option made the maximum use of the available space, but sacrificed some room in the bedrooms.

Applying environmental principles
The main environmental consideration concerned thermal zoning. Good thermal zoning avoids placing warm rooms, such as bathrooms, on the north side of a building. A central location is the optimum for thermal zoning.

Final decision
The final decision was therefore informed by practical and environmental considerations. Option one was ruled out for practical reasons, but, even if viable, would have led to poor thermal zoning. Option two was difficult and costly, and would have greatly increased the area of wall and window on the north side. Option three was the best option for meeting both practical and environmental criteria, and the ideal location for thermal zoning was between the front and rear bedrooms. Here the bathroom was in the core of the house and could be as hot as we wanted.

DESIGN PROCESS: THE ADDITIONAL WORK SPACE
The obvious place to look for the additional space for Annie’s work space was in the loft. The only viable place to insert a new set of stairs was starting in the corner of the bedroom and running directly above the existing stairs. Although, it was fine with us if we had to cross the bedroom to get to the stairs, building regulations require that any new room above the first floor must have independent access to the main stairs. A standard loft conversion would have required carving a needless corridor off the bedroom to provide independent access.

The solution, suggested by Annie and planned by our creative builder, Bill Frizell, who can quote building regs from memory, was to knock out the ceiling of the bedroom and turning the loft space into a mezzanine balcony overlooking the bedroom below. Providing that the floor area of the loft/balcony/mezzanine floor was less than half the area of the bedroom, we could argue that the loft space was an extension to the bedroom, rather than a new room, and therefore did not need an independent escape. To keep within this limited area, the mezzanine area was less than 2m across which, given the low head height of the roof, was close to the maximum useable space in any case. The remaining loft space behind the mezzanine could then be walled up with access doors so that it could be used for storage without being included in the floor area.

By a nice coincidence, this meant that the mezzanine was directly over the bathroom. By lowering the ceiling of the bathroom, we could gain an extra 30 cm in head height to the mezzanine.

It was an ingenious solution which building control was forced reluctantly to approve. Given my growing awareness that building regulations exist to confound creative and innovative design, I was not surprised that one month later an amendment banned mezzanine floors above the first floor.

Applying environmental principles
In this case, the design had been forced by practical and legal restrictions with no chance to consider environmental performance. The result was a design which posed problems for heating and insulation. Double height rooms are attractive soaring spaces but also increase heating demands. To make matters worse, the removal of the bedroom ceiling would allow all the hot air in the house to collect at the apex of the roof. The result could be a baking hot loft space that sucked heat from the rest of the house.

A double height room also creates a powerful stack effect. In summer this would be desirable, drawing air through the house. However, in winter, the stack effect would make any leakage of hot air from the roof above the mezzanine a major source of heat loss.

Finally, any loft conversion expands the outer "skin" of the house. Depending on the pitch of the roof, the area at the top of the house requiring insulation is increased by between 10% and 50%. In the Yellow House, the mezzanine increased the area of the external skin at the top of the house by 15%.

Final decision
Several changes were made to the design in response to these weaknesses. We decided to install a fan and ducting to pump the warm air from the apex of the roof into the rear extension where it was most needed (more on the fan ducting...).

Once the decision was made to install the fan, it seemed that any additional heat we could obtain was all to the good. We specified two large skylights for the south west side to increase solar heating. One was placed in the middle of the roof to allow a view from a sitting position on the mezzanine. The second was placed high in the roof as close to the apex as possible so that in summer it could function to best effect as a solar chimney. There were no windows on the north facing roof. The insulation all around the loft space was to the maximum specifications possible within the available space (more on loft insulation...)

DESIGN PROCESS: EXTENSION, UTILITIES ROOM AND SUN PORCH
After these other confusing decisions, the design of the extension was relatively straightforward. Foundations had already been dug by the previous owner one metre beyond the existing rear wall. A one storey extension of this size would have a volume of 47m3, just within the 50m3 allowed without planning permission. We therefore decided to build a low one storey extension on these new foundations.

Within a small house every decision creates a series of new problems. The decision to move the bathroom upstairs created the problem of what to do with the old bathroom space. We decided to keep the toilet, but to reconfigure the space. The old extension had housed the washing machine and freezer and had provided a space for drying clothes in winter. Our desire to use the new extension as a dining and living area meant that we would have to find a new home for these services.

Applying environmental principles
Looking at the orientation of the house, the extension would be on the north east facing side of the house. Most of the sun in the winter is crossing the back of the house from the south east. Even in summer trees block much of the easterly sun.

Clearly this was a poor place to put a warm zone living room or a one storey extension with windows. As we were not willing to reconsider our decision to use the extension for warm zone living, we gave careful thought to energy conservation measures.

The reconfiguration of the rear of the house posed new environmental opportunities as well as problems. The relocation of the bathroom created the opportunity of creating a hot zone utilities and drying space where it had previously stood. Moving the bath upstairs created an interesting opportunity to capture and use the waste bath water.

Design
The shape of the new extension was simple and regular, to add as little as possible to the area of the outer wall of the house. The insulation of the roof and walls was specified to high standards. The windows were kept to the minimum possible area that would still allow a view over the garden, with most light provided through two skylights.

Large skylights with low heat loss were specified to bring light into the kitchen. We decided to utilise the rising heat in the rear upstairs rooms. Two vents were placed at the top of the mezzanine leading through to just above floor level in the rear rooms. These could then be adjusted to control the flow of warm air from the kitchen and mezzanine into the top of the house. In summer these vents would facilitate the stack effect and draw cooler air from the rear of the house through the rear rooms.

We included a range of energy conservation features to minimise the heat loss from the extension. The windows had low heat loss glass. Insulation standards were two to three times that required by building regulations. Soil was "bermed" to the height of the windowsills and a specialist contractor installed a high insulation turf roof.

The old bathroom had been poorly constructed so we demolished it and walled in a new toilet/drying/utility room alongside the kitchen. Along with the bathroom, this meant that the three hottest rooms in the house were placed at the core of the building.

The washing machine and clothes drying racks were installed in the utility room. A laundry shoot led down from the bathroom directly above, and allowed the warm damp air to rise through the bathroom and out through the extractor fan. Reluctantly, in the interests of saving space, we had to put the freezer in the hot zone utility room, the least desirable location for refrigeration. To compensate, we reinsulated the freezer.

We re-used the old copper hot water tank, destined for the scrap yard, to store the waste bath and shower water for flushing the downstairs toilet. The tank was positioned directly above the toilet and slowly radiated the heat from the waste bath and shower water into the drying/utility room.

We decided to add a porch to the extension to reduce the heat loss through the garden doors. A solid wall on one side is orientated to pick up the south east sun. During the months of November to February the porch is mainly a draught lobby, preventing air from entering the house when we open the door. At this time it also doubles as a storage space for foodstuffs.

During spring and autumn, it captures and holds the low sun coming from the south east and open vents allow the warmed air to enter the house. During the summer one or both sets of doors are removed to allow the free flow of space and air between house and garden.

As well as providing storage for garden implements, the sun porch also doubles as a potting shed in spring and a greenhouse in summer, providing tomatoes late into the autumn. All in all, a very satisfactory addition to our original plans.