A project reducing our impact on the planet and providing
sustainable, comfortable, inexpensive living through ultra low energy.


The Tranquility Project - Design Logic

We thought about where all the energy is conventionally lost in a domestic house; where it can be gained; how it can be stored; and how the consumption of mains water could be minimised – bearing in mind that any solution to this problem needs to use minimum energy and cost as little as possible. There are 3 simple parts to the Design Logic:

The Golden Principles

The Heat Equation

The Energy Decisions



‘The Golden Principles’


* Energy Performance Measurement pre generation

* What Price is the Energy? - 8p/kw hr

* ROI – Return on Investment – 5%

* Net Total Energy – no swapping

* Minimise Total Environmental Cost

We then looked at addressing what we call ‘The Heat Equation’ for winter

Fabric Losses
+ Ventilation Losses
– Solar gain
– Anthropogenic Gain

= Heat Load


Houses only LOSE heat in 2 ways, through the structure and through ventilation and they only GAIN heat in 3 ways, with the help of a boiler, through anthropogenic gain (heat loss from humans and animals) and through solar gain.


The fabric losses are the biggest – through walls, the roof, the floor and through glazing, therefore we need to Insulate.
Why should we ventilate? Building regulations stipulate, to get rid of cooking smells, bodily smells, moisture and pollutants. The solution is therefore Intelligent Ventilation

Solar Gain is actually surprisingly good in the UK. We have many days in winter that are cloud free and full of sunshine, albeit freezing cold outside! We can still collect the heat and we need to keep what we won.


The heat emitted by humans is 110w. Also, every animal and every appliance emits heat. All these factors are accounted for in our Energy calculations.


The only thing left to do was to make ‘The Energy Decisions’ which are based on the following:


Space & water heating
Foul Drainage
Passive summer


For Space and Water heating natural gas is 1st choice, oil is 2nd but we mustn’t forget Renewables.
For Water we wanted to go for 100% independent and supply potable (drinkable) water as well.
Foul Drainage is best left to the professionals!
And finally Passive Summer – we decided - use passive ventilation in summer (no power) and do not install air conditioning.

©Tranquility Houses 2010