Building materials - adobe/mud brick walls, reinforced concrete, reinforced polystyrene block, stone/rock walls, straw bale and timber framing
Double glazing, wall insulation, a system to collect rainwater for human use such as bathing, cleaning, watering the plants, and washing the dishes are all possibilities. Reed beds allow water to be cleaned.
Alternative energy sources - wind, solar power, loft insulation and geo-thermal heating
Energy-efficient features - dual flush toilets, energy saving light bulbs, and appliances with high energy efficiency codes accreditation. Large windows provide natural lighting. !
Can you include some of these ideas in your eco-house? Think about it.