Current spectrum scarcity is result of inefficient spectrum utilization. This underutilized spectrum causes hurdle in implementation of emerging wireless technologies which require more frequency spectrum. Cognitive radio (CR) has provided a promising solution to the current spectral requirement problem by efficient spectrum sharing. Spectrum sensing (SS) is one of the key feature that has to be performed in CR networks. Many SS techniques are present based upon different parameters in the past. Among these technique, radiometric detection uses a general purpose method that can be used in all condition in spite of signal structure and signal type. But, the performance of radiometric detection scheme is greatly degraded especially in low signal to noise ratio (SNR) environments. In those situation, an appropriate setting of the detection threshold could lead to a significant improvement in detection scheme. In this paper, new scheme for radiometric detection has been proposed for low SNR environment. Simulation result shows improved performance over conventional scheme in low SNR environment.