Is it permissible for a partner in the construction and sale of a property to demand compensation for damages resulting from his partner's sale of the property at a lower price without his consent?

Your partner is your agent in the sale. As long as you have specified a certain price for him to sell your share of the property, he is not permitted to sell for less than that without referring back to you. So, if he sells for less than what you stipulated, he is responsible for the shortfall, because he violated what you had determined for him.